1
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Metlay AS, Chyi B, Sheehan CJ, Shallenberger JR, Mallouk TE. Fast Outer-Sphere Electron Transfer and High Specific Capacitance at Covalently Modified Carbon Electrodes. J Am Chem Soc 2024. [PMID: 38980188 DOI: 10.1021/jacs.4c04088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Carbon electrodes typically display sluggish electron transfer kinetics due to the adsorption of adventitious molecules that effectively insulate the surface. Here, we describe a method for rendering graphitic carbon electrodes permanently hydrophilic by functionalization with 4-(diazonium)benzenesulfonic acid. In aqueous electrolytes, these hydrophilic carbon electrodes exhibit metal-like specific capacitance (∼40 μF/cm2) as measured by cyclic voltammetry, suggesting a change in the double-layer structure at the carbon surface. Additionally, the modified electrodes show fast charge transfer kinetics to outer-sphere one-electron redox couples such as ferro-/ferricyanide as well as improved electron transfer kinetics in alkaline aqueous redox flow batteries.
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Affiliation(s)
- Amy S Metlay
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Brandon Chyi
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Colton J Sheehan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jeffrey R Shallenberger
- Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba Ibaraki 305-0044, Japan
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2
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Gaudin LF, Wright IR, Harris-Lee TR, Jayamaha G, Kang M, Bentley CL. Five years of scanning electrochemical cell microscopy (SECCM): new insights and innovations. NANOSCALE 2024; 16:12345-12367. [PMID: 38874335 DOI: 10.1039/d4nr00859f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Scanning electrochemical cell microscopy (SECCM) is a nanopipette-based technique which enables measurement of localised electrochemistry. SECCM has found use in a wide range of electrochemical applications, and due to the wider uptake of this technique in recent years, new applications and techniques have been developed. This minireview has collected all SECCM research articles published in the last 5 years, to demonstrate and celebrate the recent advances, and to make it easier for SECCM researchers to remain well-informed. The wide range of SECCM applications is demonstrated, which are categorised here into electrocatalysis, electroanalysis, photoelectrochemistry, biological materials, energy storage materials, corrosion, electrosynthesis, and instrumental development. In the collection of this library of SECCM studies, a few key trends emerge. (1) The range of materials and processes explored with SECCM has grown, with new applications emerging constantly. (2) The instrumental capabilities of SECCM have grown, with creative techniques being developed from research groups worldwide. (3) The SECCM research community has grown significantly, with adoption of the SECCM technique becoming more prominent.
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Affiliation(s)
- Lachlan F Gaudin
- School of Chemistry, Monash University, Clayton, 3800 VIC, Australia.
| | - India R Wright
- School of Chemistry, Monash University, Clayton, 3800 VIC, Australia.
| | - Thom R Harris-Lee
- School of Chemistry, Monash University, Clayton, 3800 VIC, Australia.
- Department of Chemistry, University of Bath, Claverton Down, Bath, UK
| | - Gunani Jayamaha
- School of Chemistry, University of Sydney, Camperdown, 2050 NSW, Australia
| | - Minkyung Kang
- School of Chemistry, University of Sydney, Camperdown, 2050 NSW, Australia
| | - Cameron L Bentley
- School of Chemistry, Monash University, Clayton, 3800 VIC, Australia.
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3
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Jayamaha G, Maleki M, Bentley CL, Kang M. Practical guidelines for the use of scanning electrochemical cell microscopy (SECCM). Analyst 2024; 149:2542-2555. [PMID: 38632960 DOI: 10.1039/d4an00117f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Scanning electrochemical cell microscopy (SECCM) has emerged as a transformative technology for electrochemical materials characterisation and the study of single entities, garnering global adoption by numerous research groups. While details on the instrumentation and operational principles of SECCM are readily available, the growing need for practical guidelines, troubleshooting strategies, and a systematic overview of applications and trends has become increasingly evident. This tutorial review addresses this gap by offering a comprehensive guide to the practical application of SECCM. The review begins with a discussion of recent developments and trends in the application of SECCM, before providing systematic approaches to (and the associated troubleshooting associated with) instrumental set up, probe fabrication, substrate preparation and the deployment of environmental (e.g., atmosphere and humidity) control. Serving as an invaluable resource, this tutorial review aims to equip researchers and practitioners entering the field with a comprehensive guide to essential considerations for conducting successful SECCM experiments.
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Affiliation(s)
- Gunani Jayamaha
- School of Chemistry, The University of Sydney, Camperdown, 2006 NSW, Australia.
| | - Mahin Maleki
- Institute for Frontier Materials, Deakin University, Burwood, VIC 3125, Australia
| | - Cameron L Bentley
- School of Chemistry, Monash University, Clayton, 3800 VIC, Australia
| | - Minkyung Kang
- School of Chemistry, The University of Sydney, Camperdown, 2006 NSW, Australia.
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4
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Kang M, Bentley CL, Mefford JT, Chueh WC, Unwin PR. Multiscale Analysis of Electrocatalytic Particle Activities: Linking Nanoscale Measurements and Ensemble Behavior. ACS NANO 2023; 17:21493-21505. [PMID: 37883688 PMCID: PMC10655184 DOI: 10.1021/acsnano.3c06335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/18/2023] [Indexed: 10/28/2023]
Abstract
Nanostructured electrocatalysts exhibit variations in electrochemical properties across different length scales, and the intrinsic catalytic characteristics measured at the nanoscale often differ from those at the macro-level due to complexity in electrode structure and/or composition. This aspect of electrocatalysis is addressed herein, where the oxygen evolution reaction (OER) activity of β-Co(OH)2 platelet particles of well-defined structure is investigated in alkaline media using multiscale scanning electrochemical cell microscopy (SECCM). Microscale SECCM probes of ∼50 μm diameter provide voltammograms from small particle ensembles (ca. 40-250 particles) and reveal increasing dispersion in the OER rates for samples of the same size as the particle population within the sample decreases. This suggests the underlying significance of heterogeneous activity at the single-particle level that is confirmed through single-particle measurements with SECCM probes of ∼5 μm diameter. These measurements of multiple individual particles directly reveal significant variability in the OER activity at the single-particle level that do not simply correlate with the particle size, basal plane roughness, or exposed edge plane area. In combination, these measurements demarcate a transition from an "individual particle" to an "ensemble average" response at a population size of ca. 130 particles, above which the OER current density closely reflects that measured in bulk at conventional macroscopic particle-modified electrodes. Nanoscale SECCM probes (ca. 120 and 440 nm in diameter) enable measurements at the subparticle level, revealing that there is selective OER activity at the edges of particles and highlighting the importance of the three-phase boundary where the catalyst, electrolyte, and supporting carbon electrode meet, for efficient electrocatalysis. Furthermore, subparticle measurements unveil heterogeneity in the OER activity among particles that appear superficially similar, attributable to differences in defect density within the individual particles, as well as to variations in electrical and physical contact with the support material. Overall this study provides a roadmap for the multiscale analysis of nanostructured electrocatalysts, directly demonstrating the importance of multilength scale factors, including particle structure, particle-support interaction, presence of defects, etc., in governing the electrochemical activities of β-Co(OH)2 platelet particles and ultimately guiding the rational design and optimization of these materials for alkaline water electrolysis.
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Affiliation(s)
- Minkyung Kang
- School
of Chemistry, The University of Sydney, Camperdown 2006 NSW, Australia
- Department
of Chemistry, The University of Warwick, Coventry CV4 7AL, U.K.
| | | | - J. Tyler Mefford
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - William C. Chueh
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - Patrick R. Unwin
- Department
of Chemistry, The University of Warwick, Coventry CV4 7AL, U.K.
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5
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Tarábková H, Janda P. Effect of Graphite Aging on Its Wetting Properties and Surface Blocking by Gaseous Nanodomains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14154-14161. [PMID: 37734043 PMCID: PMC10552534 DOI: 10.1021/acs.langmuir.3c02151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/11/2023] [Indexed: 09/23/2023]
Abstract
Early works considered basal planes of highly ordered pyrolytic graphite (HOPG) as hydrophobic, relatively inert materials with low electrocatalytic activity due to nonpolar sp2 carbon. On the contrary, a freshly prepared HOPG surface exhibits intrinsically mildly hydrophilic properties, with a low contact angle of water, which increases after exposure to an ambient atmosphere. This process, called aging, ascribed to adsorption of airborne hydrocarbons, is reportedly accompanied by strong decay of electron transfer kinetics, the mechanism of which is not yet fully understood. Examining both freshly prepared and aged basal plane HOPG immersed in water by PeakForce quantitative nanomechanical imaging, we have found that aged HOPG is occupied by ambient gaseous nanodomains, the existence of which is explained by incomplete wetting. They cover up to 60% of the immersed surface and their incidence is in direct relation with graphite aging time. In contrast with aged graphite, gaseous nanodomains were absent on the freshly stripped HOPG surface. It can be concluded that ambient gaseous nanodomains can prevent aged basal plane HOPG from contact with aqueous media and may thus affect processes at the solid-liquid interface.
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Affiliation(s)
- Hana Tarábková
- Department of Electrochemical
Materials, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, CZ-182 23 Prague 8, Czech Republic
| | - Pavel Janda
- Department of Electrochemical
Materials, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, CZ-182 23 Prague 8, Czech Republic
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6
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Srinivas S, Senthil Kumar SM, Senthil Kumar A. Edge and Basal Plane Anisotropy of a Preanodized Pencil Graphite Electrode Surface Revealed Using Scanning Electrochemical Microscopy and Electrocatalytic Dopamine Oxidation as a Molecular Probe. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12563-12575. [PMID: 37646227 DOI: 10.1021/acs.langmuir.3c01112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Pencil graphite (PGE), an ultralow-cost and ready-to-use disposable-type electrode, has been used for various electrochemical and electroanalytical applications after its surface anodization (PGE*, * means preanodized surface). Indeed, systematic studies on mechanistic and surface features of PGE* have not yet been explored. Herein, we report anodized pencil graphite as a model system to study molecular level insights into the surface using a scanning electrochemical microscopy (SECM) technique and dopamine (DA) electrocatalytic oxidation reaction as a molecular probe. The as-prepared PGE* showed an appreciable electronic conductivity similar to the edge-plane graphitic sites (EPPG) of the highly pyrolytic graphitic electrode (HOPG) but without any surface deterioration that occurs with HOPG due to the instability of the EPPG. Physicochemical characterizations by FESEM, FTIR, Raman, and XPS techniques revealed a flake-like exfoliated PGE* surface with higher contents of carbon-oxygen especially phenolic/alcoholic functional groups than the PGE surface. Based on the chronocoulometric experiment, the number of functional groups formed on the PGE* was calculated as 10.9 × 10-10 mol cm-2. An independent SECM technique using ferricyanide as a redox probe showed the existence of a heterogeneous surface and exhibited an improved electron transfer activity due to the flake-like graphitic island on the PGE* surface. Investigated DA electrochemical oxidation on PGE* yielded about three times enhancement in the peak current signal and about 200 mV reduction in the oxidation potential over the PGE without any serious surface fouling feature that is related to the intermediate polydopamine formation on the basal-plane graphitic surface of the underlying electrode. As an independent electroanalytical study, a prototype electrochemical sensor using PGE* as a working electrode for instant detection of DA-containing pharmaceutical samples in a 1 mL Eppendorf vial has been demonstrated.
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Affiliation(s)
- Sakthivel Srinivas
- Nano and Bioelectrochemistry Research Laboratory, Carbon Dioxide Research and Green Technology Centre, Vellore Institute of Technology, Vellore 632 014, India
| | - Sakkarapalayam Murugesan Senthil Kumar
- Electroorganic and Materials Electrochemistry Division, CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630 003, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Annamalai Senthil Kumar
- Nano and Bioelectrochemistry Research Laboratory, Carbon Dioxide Research and Green Technology Centre, Vellore Institute of Technology, Vellore 632 014, India
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore632 014, India
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7
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Bai R, Tolman NL, Peng Z, Liu H. Influence of Atmospheric Contaminants on the Work Function of Graphite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12159-12165. [PMID: 37581604 PMCID: PMC10469443 DOI: 10.1021/acs.langmuir.3c01459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/20/2023] [Indexed: 08/16/2023]
Abstract
Airborne hydrocarbon contamination occurs rapidly on graphitic surfaces and negatively impact many of their material properties, yet much of the molecular details of the contamination remains unknown. We use Kelvin probe force microscopy (KPFM) to study the time evolution of the surface potential of graphite exposed to ambient. After exfoliation in air, the surface potential of graphite is not homogeneous and contains features that are absent in the topography image. In addition, the heterogeneity of the surface potential images increased in the first few days followed by a decrease at longer exposure times. These observations are strong support of slow conformation change, phase separation, and/or dynamic displacement of the adsorbed airborne contaminants.
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Affiliation(s)
- Ruobing Bai
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Nathan L. Tolman
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Zhenbo Peng
- Chemical
Engineering College, Ningbo Polytechnic, Ningbo, Zhejiang 315806, P. R. China
| | - Haitao Liu
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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8
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de Lima LF, Ferreira AL, Ranjan I, Collman RG, de Araujo WR, de la Fuente-Nunez C. A bacterial cellulose-based and low-cost electrochemical biosensor for ultrasensitive detection of SARS-CoV-2. CELL REPORTS. PHYSICAL SCIENCE 2023; 4:101476. [PMID: 38239909 PMCID: PMC10795702 DOI: 10.1016/j.xcrp.2023.101476] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2024]
Abstract
COVID-19 has led to over 6.8 million deaths worldwide and continues to affect millions of people, primarily in low-income countries and communities with low vaccination coverage. Low-cost and rapid response technologies that enable accurate, frequent testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are crucial for outbreak prevention and infectious disease control. Here we produce and characterize cellulose fibers naturally generated by the bacterium Gluconacetobacter hansenii as an alternative biodegradable substrate for manufacturing an eco-friendly diagnostic test for COVID-19. Using this green technology, we describe a novel and label-free potentiometric diagnostic test that can detect SARS-CoV-2 within 10 min and costs US$3.50 per unit. The test has bacterial cellulose (BC) as its substrate and a carbon-based electrode modified with graphene oxide and the human angiotensin-converting enzyme-2 (ACE2) as its receptor. Our device accurately and precisely detects emerging SARS-CoV-2 variants and demonstrates exceptional sensitivity, specificity, and accuracy for tested clinical nasopharyngeal/oropharyngeal (NP/OP) samples.
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Affiliation(s)
- Lucas F. de Lima
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Departments of Bioengineering and Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Penn Institute for Computational Science, University of Pennsylvania, Philadelphia, PA, USA
- Portable Chemical Sensors Lab, Department of Analytical Chemistry, Institute of Chemistry, State University of Campinas – UNICAMP, Campinas, São Paulo, Brazil
- These authors contributed equally
| | - André L. Ferreira
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Departments of Bioengineering and Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Penn Institute for Computational Science, University of Pennsylvania, Philadelphia, PA, USA
- Portable Chemical Sensors Lab, Department of Analytical Chemistry, Institute of Chemistry, State University of Campinas – UNICAMP, Campinas, São Paulo, Brazil
- These authors contributed equally
| | - Ishani Ranjan
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Departments of Bioengineering and Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Penn Institute for Computational Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Ronald G. Collman
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William R. de Araujo
- Portable Chemical Sensors Lab, Department of Analytical Chemistry, Institute of Chemistry, State University of Campinas – UNICAMP, Campinas, São Paulo, Brazil
| | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Departments of Bioengineering and Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Penn Institute for Computational Science, University of Pennsylvania, Philadelphia, PA, USA
- Lead contact
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9
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Tolman N, Bai R, Liu H. Hydrocarbons in the Meniscus: Effects on Conductive Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:4274-4281. [PMID: 36935562 PMCID: PMC10061924 DOI: 10.1021/acs.langmuir.2c03222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 02/26/2023] [Indexed: 06/18/2023]
Abstract
It is commonly accepted that during conductive atomic force microscopy (CAFM) measurement in ambient, a liquid meniscus can form between the tip and the sample. Such a liquid bridge, normally assumed to be composed of water, is a major factor in analyzing and understanding CAFM results. Here, we show that the adsorption of adventitious hydrocarbons from the air to a surface can greatly affect CAFM data both in imaging mode and in local spectroscopy (current-voltage or I-V curves). We propose a model to explain the phenomena whereby hydrocarbon contaminates contribute to the composition of the liquid bridge between the tip and the sample.
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10
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Srinivas S, Senthil Kumar A. Surface-Activated Pencil Graphite Electrode for Dopamine Sensor Applications: A Critical Review. BIOSENSORS 2023; 13:353. [PMID: 36979565 PMCID: PMC10046220 DOI: 10.3390/bios13030353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/22/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Pencil graphite electrode (PGE) is an alternative, commercially available, ready-to-use, screen-printed electrode for a wide range of electroanalytical applications. Due to the complex-matrix composition and unpredictable electro-inactive nature of PGE in its native form, a surface pre-treatment/activation procedure is highly preferred for using it as an electroactive working electrode for electroanalytical applications. In this article, we review various surface pre-treatment and modification procedures adopted in the literature with respect to the sensitive and selective detection of dopamine as a model system. Specific generation of the carbon-oxygen functional group, along with partial surface exfoliation of PGE, has been referred to as a key step for the activation. Based on the Scopus® index, the literature collection was searched with the keywords "pencil and dopamine". The obtained data were segregated into three main headings as: (i) electrochemically pre-treated PGE; (ii) polymer-modified PGEs; and (iii) metal and metal nanocomposite-modified PGE. This critical review covers various surface activation procedures adopted for the activation for PGE suitable for dopamine electroanalytical application.
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Affiliation(s)
- Sakthivel Srinivas
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, India
| | - Annamalai Senthil Kumar
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, India
- Nano and Bioelectrochemistry Research Laboratory, Carbon Dioxide Research and Green Technology Centre, Vellore Institute of Technology, Vellore 632 014, India
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11
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Pálinkás A, Kálvin G, Vancsó P, Kandrai K, Szendrő M, Németh G, Németh M, Pekker Á, Pap JS, Petrik P, Kamarás K, Tapasztó L, Nemes-Incze P. The composition and structure of the ubiquitous hydrocarbon contamination on van der Waals materials. Nat Commun 2022; 13:6770. [PMID: 36351922 PMCID: PMC9646725 DOI: 10.1038/s41467-022-34641-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 11/02/2022] [Indexed: 11/10/2022] Open
Abstract
The behavior of single layer van der Waals (vdW) materials is profoundly influenced by the immediate atomic environment at their surface, a prime example being the myriad of emergent properties in artificial heterostructures. Equally significant are adsorbates deposited onto their surface from ambient. While vdW interfaces are well understood, our knowledge regarding atmospheric contamination is severely limited. Here we show that the common ambient contamination on the surface of: graphene, graphite, hBN and MoS2 is composed of a self-organized molecular layer, which forms during a few days of ambient exposure. Using low-temperature STM measurements we image the atomic structure of this adlayer and in combination with infrared spectroscopy identify the contaminant molecules as normal alkanes with lengths of 20-26 carbon atoms. Through its ability to self-organize, the alkane layer displaces the manifold other airborne contaminant species, capping the surface of vdW materials and possibly dominating their interaction with the environment. Here, the authors attribute the ambient surface contamination of van der Waals materials to a self-organized molecular layer of normal alkanes with lengths of 20-26 carbon atoms. The alkane adlayer displaces the manifold other airborne contaminant species, capping the surface of graphene, graphite, hBN and MoS2.
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12
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Li Y, Morel A, Gallant D, Mauzeroll J. Controlling Surface Contact, Oxygen Transport, and Pitting of Surface Oxide via Single-Channel Scanning Electrochemical Cell Microscopy. Anal Chem 2022; 94:14603-14610. [PMID: 36214771 DOI: 10.1021/acs.analchem.2c02459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In single-channel scanning electrochemical cell microscopy, the applied potential during the approach of a micropipette to the substrate generates a transient current upon droplet contact with the substrate. Once the transient current exceeds a set threshold, the micropipette is automatically halted. Currently, the effect of the approach potential on the subsequent electrochemical measurements, such as the open-circuit potential and potentiodynamic polarization, is considered to be inconsequential. Herein, we demonstrate that the applied approach potential does impact the extent of probe-to-substrate interaction and subsequent microscale electrochemical measurements on aluminum alloy AA7075-T73.
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Affiliation(s)
- Yuanjiao Li
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, H3A 0B8 Quebec, Canada
| | - Alban Morel
- Automotive and Surface Transportation Research Centre, Division of Transportation and Manufacturing, National Research Council Canada, Aluminum Technology Center, 501 University Blvd East, Saguenay, G7H 8C3 Quebec, Canada
| | - Danick Gallant
- Automotive and Surface Transportation Research Centre, Division of Transportation and Manufacturing, National Research Council Canada, Aluminum Technology Center, 501 University Blvd East, Saguenay, G7H 8C3 Quebec, Canada
| | - Janine Mauzeroll
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, H3A 0B8 Quebec, Canada
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13
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Electrochemical Properties of Carbon Fibers from Felts. Molecules 2022; 27:molecules27196584. [PMID: 36235121 PMCID: PMC9572839 DOI: 10.3390/molecules27196584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 09/23/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
Electrochemical behaviors of individual carbon fibers coming from carbon felts were investigated using two different redox couples, 1,1'-dimethanolferrocene and potassium ferrocyanide. Electrochemical responses were examined after different oxidation treatments, then simulated and interpreted using the Kissa 1D software and existing models. Our experiments indicate that a crude carbon fiber behaves as an assembly of sites with different electrochemical reactivities. In such case, the Butler-Volmer law is not appropriate to describe the electron transfer kinetics because of the large created overpotential. Oxidation of the fiber erases the effect by increasing the kinetics of the electron transfer probably by a homogenization and increase of the reactivity on all the fiber. Additionally, analysis of the signal shows the large influence of the convection that affects the electrochemical response even at moderate scan rates (typically below 0.1-0.2 V s-1).
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14
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Stolz R, Kolln AF, Rocha BC, Brinks A, Eagleton AM, Mendecki L, Vashisth H, Mirica KA. Epitaxial Self-Assembly of Interfaces of 2D Metal-Organic Frameworks for Electroanalytical Detection of Neurotransmitters. ACS NANO 2022; 16:13869-13883. [PMID: 36099649 PMCID: PMC9527791 DOI: 10.1021/acsnano.2c02529] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 08/31/2022] [Indexed: 05/19/2023]
Abstract
This paper identifies the electrochemical properties of individual facets of anisotropic layered conductive metal-organic frameworks (MOFs) based on M3(2,3,6,7,10,11-hexahydroxytriphenylene)2 (M3(HHTP)2) (M = Co, Ni). The electroanalytical advantages of each facet are then applied toward the electrochemical detection of neurochemicals. By employing epitaxially controlled deposition of M3(HHTP)2 MOFs on electrodes, the contribution of the basal plane ({001} facets) and edge sites ({100} facets) of these MOFs can be individually determined using electrochemical characterization techniques. Despite having a lower observed heterogeneous electron transfer rate constant, the {001} facets of the M3(HHTP)2 systems prove more selective and sensitive for the detection of dopamine than the {100} facets of the same MOF, with the limit of detection (LOD) of 9.9 ± 2 nM in phosphate-buffered saline and 214 ± 48 nM in a simulated cerebrospinal fluid. Langmuir isotherm studies accompanied by all-atom MD simulations suggested that the observed improvement in performance and selectivity is related to the adsorption characteristics of analytes on the basal plane versus edge sites of the MOF interfaces. This work establishes that the distinct crystallographic facets of 2D MOFs can be used to control the fundamental interactions between analyte and electrode, leading to tunable electrochemical properties by controlling their preferential orientation through self-assembly.
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Affiliation(s)
- Robert
M. Stolz
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
| | - Anna F. Kolln
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
| | - Brunno C. Rocha
- Department
of Chemical Engineering, Kingsbury Hall, University of New Hampshire, 33 Academic Way, Durham, New Hampshire 03824, United States
| | - Anna Brinks
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
| | - Aileen M. Eagleton
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
| | - Lukasz Mendecki
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
| | - Harish Vashisth
- Department
of Chemical Engineering, Kingsbury Hall, University of New Hampshire, 33 Academic Way, Durham, New Hampshire 03824, United States
| | - Katherine A. Mirica
- Department
of Chemistry, Burke Laboratory, Dartmouth
College, 41 College Street, Hanover, New Hampshire 03755, United States
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15
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Inozemtseva AI, Sergeev AV, Napolskii KS, Kushnir SE, Belov V, Itkis DM, Usachov DY, Yashina LV. Graphene electrochemistry: ‘Adiabaticity’ of electron transfer. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Caniglia G, Tezcan G, Meloni GN, Unwin PR, Kranz C. Probing and Visualizing Interfacial Charge at Surfaces in Aqueous Solution. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2022; 15:247-267. [PMID: 35259914 DOI: 10.1146/annurev-anchem-121521-122615] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Surface charge density and distribution play an important role in almost all interfacial processes, influencing, for example, adsorption, colloidal stability, functional material activity, electrochemical processes, corrosion, nanoparticle toxicity, and cellular processes such as signaling, absorption, and adhesion. Understanding the heterogeneity in, and distribution of, surface and interfacial charge is key to elucidating the mechanisms underlying reactivity, the stability of materials, and biophysical processes. Atomic force microscopy (AFM) and scanning ion conductance microscopy (SICM) are highly suitable for probing the material/electrolyte interface at the nanoscale through recent advances in probe design, significant instrumental (hardware and software) developments, and the evolution of multifunctional imaging protocols. Here, we assess the capability of AFM and SICM for surface charge mapping, covering the basic underpinning principles alongside experimental considerations. We illustrate and compare the use of AFM and SICM for visualizing surface and interfacial charge with examples from materials science, geochemistry, and the life sciences.
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Affiliation(s)
- Giada Caniglia
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany;
| | - Gözde Tezcan
- Department of Chemistry, University of Warwick, Coventry, United Kingdom;
| | - Gabriel N Meloni
- Department of Chemistry, University of Warwick, Coventry, United Kingdom;
| | - Patrick R Unwin
- Department of Chemistry, University of Warwick, Coventry, United Kingdom;
| | - Christine Kranz
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany;
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17
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Let’s twist electrochem. Nat Chem 2022; 14:248-250. [DOI: 10.1038/s41557-022-00900-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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19
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Liu DQ, Kang M, Perry D, Chen CH, West G, Xia X, Chaudhuri S, Laker ZPL, Wilson NR, Meloni GN, Melander MM, Maurer RJ, Unwin PR. Adiabatic versus non-adiabatic electron transfer at 2D electrode materials. Nat Commun 2021; 12:7110. [PMID: 34876571 PMCID: PMC8651748 DOI: 10.1038/s41467-021-27339-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/15/2021] [Indexed: 01/04/2023] Open
Abstract
2D electrode materials are often deployed on conductive supports for electrochemistry and there is a great need to understand fundamental electrochemical processes in this electrode configuration. Here, an integrated experimental-theoretical approach is used to resolve the key electronic interactions in outer-sphere electron transfer (OS-ET), a cornerstone elementary electrochemical reaction, at graphene as-grown on a copper electrode. Using scanning electrochemical cell microscopy, and co-located structural microscopy, the classical hexaamineruthenium (III/II) couple shows the ET kinetics trend: monolayer > bilayer > multilayer graphene. This trend is rationalized quantitatively through the development of rate theory, using the Schmickler-Newns-Anderson model Hamiltonian for ET, with the explicit incorporation of electrostatic interactions in the double layer, and parameterized using constant potential density functional theory calculations. The ET mechanism is predominantly adiabatic; the addition of subsequent graphene layers increases the contact potential, producing an increase in the effective barrier to ET at the electrode/electrolyte interface.
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Affiliation(s)
- Dan-Qing Liu
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK ,grid.13402.340000 0004 1759 700XSchool of Materials Science and Engineering, Zhejiang University, Hangzhou, 310007 China
| | - Minkyung Kang
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK ,grid.1021.20000 0001 0526 7079Institute for Frontier Materials, Deakin University, Geelong, VIC 3217 Australia
| | - David Perry
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
| | - Chang-Hui Chen
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
| | - Geoff West
- grid.7372.10000 0000 8809 1613Warwick Manufacturing Group, University of Warwick, Coventry, CV4 7AL UK
| | - Xue Xia
- grid.7372.10000 0000 8809 1613Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Shayantan Chaudhuri
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK ,grid.7372.10000 0000 8809 1613Centre for Doctoral Training in Diamond Science and Technology, University of Warwick, Coventry, CV4 7AL UK
| | - Zachary P. L. Laker
- grid.7372.10000 0000 8809 1613Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Neil R. Wilson
- grid.7372.10000 0000 8809 1613Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Gabriel N. Meloni
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
| | - Marko M. Melander
- grid.9681.60000 0001 1013 7965Department of Chemistry, Nanoscience Center, University of Jyväskylä, P.O. Box 35, (YN) FI-40014 Jyväskylä, Finland
| | - Reinhard J. Maurer
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
| | - Patrick R. Unwin
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
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20
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Martín‐Yerga D, Kang M, Unwin PR. Scanning Electrochemical Cell Microscopy in a Glovebox: Structure‐Activity Correlations in the Early Stages of Solid‐Electrolyte Interphase Formation on Graphite. ChemElectroChem 2021. [DOI: 10.1002/celc.202101161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Daniel Martín‐Yerga
- Department of Chemistry University of Warwick Coventry CV47AL United Kingdom
- The Faraday Institution Quad One, Harwell Campus Didcot OX11 0RA United Kingdom
| | - Minkyung Kang
- Department of Chemistry University of Warwick Coventry CV47AL United Kingdom
- Institute for Frontier Materials Deakin University Burwood VIC 3125 Australia
| | - Patrick R. Unwin
- Department of Chemistry University of Warwick Coventry CV47AL United Kingdom
- The Faraday Institution Quad One, Harwell Campus Didcot OX11 0RA United Kingdom
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21
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Liu G, Xiong Z, Yang L, Shi H, Fang D, Wang M, Shao P, Luo X. Electrochemical approach toward reduced graphene oxide-based electrodes for environmental applications: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 778:146301. [PMID: 33725599 DOI: 10.1016/j.scitotenv.2021.146301] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 03/02/2021] [Accepted: 03/02/2021] [Indexed: 05/27/2023]
Abstract
Graphene has shown great potential in various application fields due to its excellent carrier transportation, ultra-high specific surface area, good mechanical properties, and light transmittance. However, pure graphene still exhibits some insurmountable defects, such as difficulty in simple and large-scale preparation, and limitations in application. The electrochemical method is a simple, clean, and environmentally friendly method. The rapid and simple preparation of graphene and its derivatives by electrochemical methods has important environmental significance. Moreover, rGO-based nanohybrids can be prepared by convenient and quick electrodeposition or cyclic voltammetry (CV), or to change the morphology and structure of graphene and its derivatives to achieve the purpose of improving material properties. This work mainly summarizes electrochemically related graphene from four aspects: (i) the method of electrochemical exfoliation of graphene; (ii) types of electrodeposition rGO-based nanohybrids; (iii) electrochemical regulation of the structure of rGO-based mixtures; (iv) environmental applications of rGO-based nanohybrids prepared by electrodeposition. This article critically discusses the advantages and disadvantages of electrochemical-related graphene, outlines future challenges, and provides insightful views and references for other researchers.
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Affiliation(s)
- Guangzhen Liu
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Zhensheng Xiong
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Liming Yang
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China.
| | - Hui Shi
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Difan Fang
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Mei Wang
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Penghui Shao
- National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization, Nanchang Hangkong University, Nanchang 330063, PR China; Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Xubiao Luo
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China.
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22
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Musa AM, Kiely J, Luxton R, Honeychurch KC. Recent progress in screen-printed electrochemical sensors and biosensors for the detection of estrogens. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116254] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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23
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Mirbagheri N, Campos R, Ferapontova EE. Electrocatalytic Oxidation of Water by OH
−
‐ and H
2
O‐Capped IrO
x
Nanoparticles Electrophoretically Deposited on Graphite and Basal Plane HOPG: Effect of the Substrate Electrode**. ChemElectroChem 2021. [DOI: 10.1002/celc.202100317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Naghmehalsadat Mirbagheri
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
- Department of Microsystems Engineering – IMTEK University of Freiburg Georges-Koehler-Allee 103 79110 Freiburg Germany
| | - Rui Campos
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
- AXES research group and NANOlab Center of Excellence University of Antwerp Groenenborgerlaan 171 2020 Antwerpen Belgium
| | - Elena E. Ferapontova
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University Gustav Wieds Vej 1590-14 DK-8000 Aarhus C Denmark
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24
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Abstract
AbstractGraphene as a two-dimensional material is prone to hydrocarbon contaminations, which can significantly alter its intrinsic electrical properties. Herein, we implement a facile hydrogenation-dehydrogenation strategy to remove hydrocarbon contaminations and preserve the excellent transport properties of monolayer graphene. Using electron microscopy we quantitatively characterized the improved cleanness of hydrogenated graphene compared to untreated samples. In situ spectroscopic investigations revealed that the hydrogenation treatment promoted the adsorption ofytyt water at the graphene surface, resulting in a protective layer against the re-deposition of hydrocarbon molecules. Additionally, the further dehydrogenation of hydrogenated graphene rendered a more pristine-like basal plane with improved carrier mobility compared to untreated pristine graphene. Our findings provide a practical post-growth cleaning protocol for graphene with maintained surface cleanness and lattice integrity to systematically carry a range of surface chemistry in the form of a well-performing and reproducible transistor.
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25
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Rabboh FM, O'Neil GD. Voltammetric pH Measurements in Unadulterated Foodstuffs, Urine, and Serum with 3D-Printed Graphene/Poly(Lactic Acid) Electrodes. Anal Chem 2020; 92:14999-15006. [PMID: 33140638 DOI: 10.1021/acs.analchem.0c02902] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The pH of a system is a critical descriptor of its chemistry-impacting reaction rates, solubility, chemical speciation, and homeostasis. As a result, pH is one of the most commonly measured parameters in food safety, clinical, and environmental laboratories. Glass pH probes are the gold standard for pH measurements but suffer drawbacks including frequent recalibration, wet storage of the glass membrane, difficulty in miniaturization, and interferences from alkali metals. In this work, we describe a voltammetric pH sensor that uses a three-dimensional (3D)-printed graphene/poly(lactic acid) filament electrode that is pretreated to introduce quinone functional groups to the graphene surface. After thoroughly characterizing the pretreatment parameters using outer-sphere and inner-sphere redox couples, we measured pH by reducing the surface-bound quinones, which undergo a pH-dependent 2e-/2H+ reduction. The position of the redox peak was found to shift -60 ± 2 mV pH-1 at 25 °C, which is in excellent agreement with the theoretical value predicted by the Nernst Equation (-59.2 mV pH-1). Importantly, the sensors did not require the removal of dissolved oxygen prior to successful pH measurements. We investigated the impact of common interfering species (Pb2+ and Cu2+) and found that there was no impact on the measured pH. We subsequently challenged the sensors to measure the pH of unadulterated complex samples, including cola, vinegar, an antacid tablet slurry, serum, and urine, and obtained excellent agreement compared to a glass pH electrode. In addition to the positive analytical characteristics, the sensors are extremely cheap and easy to fabricate, making them highly accessible to a wide range of researchers. These results pave the way for customizable pH sensors that can be fabricated in (nearly) any geometry for targeted applications using 3D printing.
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Affiliation(s)
- Fakher M Rabboh
- Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey 07043, United States
| | - Glen D O'Neil
- Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey 07043, United States
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26
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Rong K, Wei J, Huang L, Fang Y, Dong S. Synthesis of low dimensional hierarchical transition metal oxides via a direct deep eutectic solvent calcining method for enhanced oxygen evolution catalysis. NANOSCALE 2020; 12:20719-20725. [PMID: 33029600 DOI: 10.1039/d0nr04378h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transition metal oxides (TMOs) are regarded as important materials due to their wide applications in catalysis, sensors, energy storage and conversion devices owing to their advantages of facile synthesis, low cost, and high activity. Here we develop a direct deep eutectic solvent (DES) calcining method to prepare low-dimensional and highly active TMOs for the electrochemical oxygen evolution reaction (OER). Glucose monohydrate and urea can form a glucose-urea DES, which was calcined under a N2 atmosphere to produce 2D N,O-doped graphene. When metal precursors were introduced into the glucose-urea DES and calcined together, the TMOs were templated by graphene flakes and exhibited low-dimensional morphologies. With this method, 2D nanonet-shaped La0.5Sr0.5Co0.8Fe0.2O3 (LSCF), Co3O4, NiCo2O4, and RuO2 and 1D nanowire-shaped Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF) were readily synthesized, and their thickness and porosity can be conveniently tuned by adjusting the concentrations of metal salts. Our nanostructured TMOs were further applied for the OER, and they showed quite competitive activities over their counterparts obtained from other methods. The 2D porous LSCF20-DES exhibited the largest specific surface area (28.9 m2 g-1) and the highest OER electrocatalytic activities (0.304 V overpotential at a current density of 10 mA cm-2). These results demonstrate that the DES calcining method is a comprehensive approach to synthesize hierarchical TMOs as highly active OER catalysts.
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Affiliation(s)
- Kai Rong
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China. and University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Jiale Wei
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China. and University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Liang Huang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China. and University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Youxing Fang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China.
| | - Shaojun Dong
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China. and University of Science and Technology of China, Hefei, Anhui 230026, P. R. China and University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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27
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Pandhi T, Cornwell C, Fujimoto K, Barnes P, Cox J, Xiong H, Davis PH, Subbaraman H, Koehne JE, Estrada D. Fully inkjet-printed multilayered graphene-based flexible electrodes for repeatable electrochemical response. RSC Adv 2020; 10:38205-38219. [PMID: 35517530 PMCID: PMC9057201 DOI: 10.1039/d0ra04786d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/09/2020] [Indexed: 12/30/2022] Open
Abstract
Graphene has proven to be useful in biosensing applications. However, one of the main hurdles with printed graphene-based electrodes is achieving repeatable electrochemical performance from one printed electrode to another. We have developed a consistent fabrication process to control the sheet resistance of inkjet-printed graphene electrodes, thereby accomplishing repeatable electrochemical performance. Herein, we investigated the electrochemical properties of multilayered graphene (MLG) electrodes fully inkjet-printed (IJP) on flexible Kapton substrates. The electrodes were fabricated by inkjet printing three materials – (1) a conductive silver ink for electrical contact, (2) an insulating dielectric ink, and (3) MLG ink as the sensing material. The selected materials and fabrication methods provided great control over the ink rheology and material deposition, which enabled stable and repeatable electrochemical response: bending tests revealed the electrochemical behavior of these sensors remained consistent over 1000 bend cycles. Due to the abundance of structural defects (e.g., edge defects) present in the exfoliated graphene platelets, cyclic voltammetry (CV) of the graphene electrodes showed good electron transfer (k = 1.125 × 10−2 cm s−1) with a detection limit (0.01 mM) for the ferric/ferrocyanide redox couple, [Fe(CN)6]−3/−4, which is comparable or superior to modified graphene or graphene oxide-based sensors. Additionally, the potentiometric response of the electrodes displayed good sensitivity over the pH range of 4–10. Moreover, a fully IJP three-electrode device (MLG, platinum, and Ag/AgCl) also showed quasi-reversibility compared to a single IJP MLG electrode device. These findings demonstrate significant promise for scalable fabrication of a flexible, low cost, and fully-IJP wearable sensor system needed for space, military, and commercial biosensing applications. A fully inkjet printed and flexible multilayer graphene based three electrode device showed electrochemical reversibility.![]()
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Affiliation(s)
- Twinkle Pandhi
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA
| | - Casey Cornwell
- Department of Chemistry, Northwest Nazarene University Nampa ID 83686 USA
| | - Kiyo Fujimoto
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA
| | - Pete Barnes
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA
| | - Jasmine Cox
- Department of Electrical and Computer Engineering, Boise State University Boise ID 83725-2075 USA
| | - Hui Xiong
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA
| | - Paul H Davis
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA
| | - Harish Subbaraman
- Department of Electrical and Computer Engineering, Boise State University Boise ID 83725-2075 USA
| | | | - David Estrada
- Micron School of Materials Science and Engineering, Boise State University Boise ID 83725-2090 USA .,Center for Advanced Energy Studies, Boise State University Boise ID 83725-1012 USA
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28
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Pan Z, Yu F, Li L, Liu M, Song C, Yang J, Li H, Wang C, Pan Y, Wang T. Electrochemical filtration carbon membrane derived from coal for wastewater treatment: Insights into the evolution of electrical conductivity and electrochemical performance during carbonization. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116948] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Li Y, Morel A, Gallant D, Mauzeroll J. Oil-Immersed Scanning Micropipette Contact Method Enabling Long-term Corrosion Mapping. Anal Chem 2020; 92:12415-12422. [PMID: 32786459 DOI: 10.1021/acs.analchem.0c02177] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This work reports the development of an oil-immersed scanning micropipette contact method, a variant of the scanning micropipette contact method, where a thin layer of oil wets the investigated substrate. The oil-immersed scanning micropipette contact method significantly increases the droplet stability, allowing for prolonged mapping and the use of highly evaporative saline solutions regardless of ambient humidity levels. This systematic mapping technique was used to conduct a detailed investigation of localized corrosion taking place at the surface of an AA7075-T73 aluminum alloy in a 3.5 wt % NaCl electrolyte solution, which is typically challenging in the conventional scanning micropipette contact method. Maps of corrosion potentials and corrosion currents extracted from potentiodynamic polarization curves showed good correlations with the chemical composition of surface features and known galvanic interactions at the microscale level. This demonstrates the viability of the oil-immersed scanning micropipette contact method and opens up the avenue to mechanistic corrosion investigations at the microscale level using aqueous solutions that are prone to evaporation under noncontrolled humidity levels.
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Affiliation(s)
- Yuanjiao Li
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, H3A 0B8 Quebec, Canada
| | - Alban Morel
- Automotive and Surface Transportation Research Centre, Division of Transportation and Manufacturing, National Research Council Canada, 75 de Mortagne Blvd, Boucherville, J4B 6Y4 Quebec, Canada
| | - Danick Gallant
- Automotive and Surface Transportation Research Centre, Division of Transportation and Manufacturing, Aluminum Technology Center, National Research Council Canada, 501 University Blvd East, Saguenay, G7H 8C3 Quebec, Canada
| | - Janine Mauzeroll
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, H3A 0B8 Quebec, Canada
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30
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Nguyen TP, McCreery RL, McDermott MT. Evaluation of the electroanalytical performance of carbon-on-gold films prepared by electron-beam evaporation. Analyst 2020; 145:5041-5052. [PMID: 32555909 DOI: 10.1039/d0an00409j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carbon film electrodes can often be used without pretreatment, and their fabrication allows for flexibility in size and shape and for mass production. In this work, we are exploring layered structures comprised of thin films of carbon on gold (eC/Au) prepared by electron-beam evaporation. These extremely flat films are not pyrolyzed and are comprised of mainly amorphous carbon but still exhibit reasonable conductivity due to the underlying gold layer. eC/Au electrodes, without any pretreatment, yield similar heterogeneous electron-transfer rates for benchmark redox systems and significantly lower background current in comparison with polished glassy carbon. Interestingly, they show insignificant adsorption of quinones, which is uncommon for most carbon electrode materials. However, eC/Au is still prone to adsorption of airborne hydrocarbons when exposed to ambient air like most graphitic materials. With reproducibly fast electron transfer kinetics, low background current, negligible adsorption, and ultraflat surface, eC/Au films are a promising candidate for electrochemical and sensor applications.
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Affiliation(s)
- Thuy P Nguyen
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2N4, Canada.
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31
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Iamprasertkun P, Ejigu A, Dryfe RAW. Understanding the electrochemistry of "water-in-salt" electrolytes: basal plane highly ordered pyrolytic graphite as a model system. Chem Sci 2020; 11:6978-6989. [PMID: 34122994 PMCID: PMC8159404 DOI: 10.1039/d0sc01754j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/05/2020] [Indexed: 12/21/2022] Open
Abstract
A new approach to expand the accessible voltage window of electrochemical energy storage systems, based on so-called "water-in-salt" electrolytes, has been expounded recently. Although studies of transport in concentrated electrolytes date back over several decades, the recent demonstration that concentrated aqueous electrolyte systems can be used in the lithium ion battery context has rekindled interest in the electrochemical properties of highly concentrated aqueous electrolytes. The original aqueous lithium ion battery conception was based on the use of concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide, although these electrolytes still possess some drawbacks including cost, toxicity, and safety. In this work we describe the electrochemical behavior of a simple 1 : 1 electrolyte based on highly concentrated aqueous solutions of potassium fluoride (KF). Highly ordered pyrolytic graphite (HOPG) is used as well-defined model carbon to study the electrochemical properties of the electrolyte, as well as its basal plane capacitance, from a microscopic perspective: the KF electrolyte exhibits an unusually wide potential window (up to 2.6 V). The faradaic response on HOPG is also reported using K3Fe(CN)6 as a model redox probe: the highly concentrated electrolyte provides good electrochemical reversibility and protects the HOPG surface from adsorption of contaminants. Moreover, this electrolyte was applied to symmetrical supercapacitors (using graphene and activated carbon as active materials) in order to quantify its performance in energy storage applications. It is found that the activated carbon and graphene supercapacitors demonstrate high gravimetric capacitance (221 F g-1 for activated carbon, and 56 F g-1 for graphene), a stable working voltage window of 2.0 V, which is significantly higher than the usual range of water-based capacitors, and excellent stability over 10 000 cycles. These results provide fundamental insight into the wider applicability of highly concentrated electrolytes, which should enable their application in future of energy storage technologies.
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Affiliation(s)
- Pawin Iamprasertkun
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Andinet Ejigu
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Robert A W Dryfe
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
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Shellard PM, Srisubin T, Hartmann M, Butcher J, Fei F, Cox H, McNamara TP, McArdle T, Shepherd AM, Jacobs RMJ, Waigh TA, Flitsch SL, Blanford CF. A versatile route to edge-specific modifications to pristine graphene by electrophilic aromatic substitution. JOURNAL OF MATERIALS SCIENCE 2020; 55:10284-10302. [PMID: 32536720 PMCID: PMC7266800 DOI: 10.1007/s10853-020-04662-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
Electrophilic aromatic substitution produces edge-specific modifications to CVD graphene and graphene nanoplatelets that are suitable for specific attachment of biomolecules.
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Affiliation(s)
- Philippa M. Shellard
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
| | - Thunyaporn Srisubin
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL UK
| | - Mirja Hartmann
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
| | - Joseph Butcher
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
| | - Fan Fei
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL UK
| | - Henry Cox
- Biological Physics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Photon Science Institute, University of Manchester, Alan Turing Building, Oxford Road, Manchester, M13 9PL UK
| | - Thomas P. McNamara
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL UK
| | - Trevor McArdle
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL UK
| | - Ashley M. Shepherd
- Chemical Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA UK
| | - Robert M. J. Jacobs
- Chemical Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA UK
| | - Thomas A. Waigh
- Biological Physics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Photon Science Institute, University of Manchester, Alan Turing Building, Oxford Road, Manchester, M13 9PL UK
| | - Sabine L. Flitsch
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL UK
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
| | - Christopher F. Blanford
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL UK
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Influence of defects in graphene on electron transfer kinetics: The role of the surface electronic structure. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.136011] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Tang B, Shao W, Groenewold J, Li H, Feng Y, Xu X, Shui L, Barman J, Zhou G. Transition of interfacial capacitors in electrowetting on a graphite surface by ion intercalation. Phys Chem Chem Phys 2019; 21:26284-26291. [PMID: 31602437 DOI: 10.1039/c9cp04436a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The low voltage electrowetting response of a LiCl aqueous solution on a freshly cleaved surface of highly oriented pyrolytic graphite (HOPG) is presented. For applied voltages below 1 V, the energy stored in the electrical double layer (EDL) is insufficient to drive the spreading of the drop due to the pinning of the three phase contact line at the step edges. Electrochemical impedance spectroscopy shows a dramatic increase in capacitance above 1 V, which provides a sufficient electrowetting force for depinning the contact line, resulting in a subsequent decrease of the contact angle. The transition of the interfacial capacitance from the EDL to the many-fold high capacitance of the pseudocapacitor drives the electrowetting transition on the HOPG surface. The observed changes in the capacitances above 1 V are correlated with the cyclic voltammetry and atomic force microscopy results, which show that the Cl- ions intercalate into the graphite galleries upon acquiring sufficient energy to overcome the van der Waals attraction between the graphene layers through the side of the step edge of the basal planes. To the best of our knowledge, this is the first study on the voltage dependent intercalation mediated transition of interfacial capacitance driving the spreading of an aqueous electrolyte drop on the HOPG surface, which provides a fundamental understanding of the mechanism and opens up potential applications in microfluidics and charge storage technologies.
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Affiliation(s)
- Biao Tang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China.
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García-Miranda Ferrari A, Brownson DAC, Banks CE. Investigating the Integrity of Graphene towards the Electrochemical Hydrogen Evolution Reaction (HER). Sci Rep 2019; 9:15961. [PMID: 31685906 PMCID: PMC6828781 DOI: 10.1038/s41598-019-52463-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/17/2019] [Indexed: 11/21/2022] Open
Abstract
Mono-, few-, and multilayer graphene is explored towards the electrochemical Hydrogen Evolution Reaction (HER). Careful physicochemical characterisation is undertaken during electrochemical perturbation revealing that the integrity of graphene is structurally compromised. Electrochemical perturbation, in the form of electrochemical potential scanning (linear sweep voltammetry), as induced when exploring the HER using monolayer graphene, creates defects upon the basal plane surface that increases the coverage of edge plane sites/defects resulting in an increase in the electrochemical reversibility of the HER process. This process of improved HER performance occurs up to a threshold, where substantial break-up of the basal sheet occurs, after which the electrochemical response decreases; this is due to the destruction of the sheet integrity and lack of electrical conductive pathways. Importantly, the severity of these changes is structurally dependent on the graphene variant utilised. This work indicates that multilayer graphene has more potential as an electrochemical platform for the HER, rather than that of mono- and few-layer graphene. There is huge potential for this knowledge to be usefully exploited within the energy sector and beyond.
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Affiliation(s)
- Alejandro García-Miranda Ferrari
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
- Manchester Fuel Cell Innovation Centre, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
| | - Dale A C Brownson
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
- Manchester Fuel Cell Innovation Centre, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
| | - Craig E Banks
- Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
- Manchester Fuel Cell Innovation Centre, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
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Xiao Y, Su Y, Liu X, Xu W. Defect-Driven Heterogeneous Electron Transfer between an Individual Graphene Sheet and Electrode. J Phys Chem Lett 2019; 10:5402-5407. [PMID: 31460765 DOI: 10.1021/acs.jpclett.9b02134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Understanding the heterogeneous electron-transfer (ET) kinetics on graphene is essential for its extensive applications. Here, on the basis of the redox-induced fluorescence variation of monolayer graphene itself, the heterogeneous ET kinetics at the interface between the electrode and the monolayer graphene was studied label-freely at the single-sheet level. By tuning the defect density on graphene, an optimal heterogeneous ET rate was observed at a moderate defect density, indicating defect-driven ET kinetics. The heterogeneities of both the intrasheet and intersheet ET kinetics were revealed at the single-sheet level. With the optimal defective graphene sheets as a sensing material for oxygen gas, a cost-effective electrochemical oxygen sensor was obtained with high sensitivity, fast response/recovery, and remarkable durability. The results obtained here deepen our understanding of the electrochemical properties of graphene and imply that rational defect control can enhance the ET process between the electrode and graphene and then improve the performance of graphene-based functional materials or devices.
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Affiliation(s)
- Yi Xiao
- State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun , Jilin 130022 , People's Republic of China
- University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Yi Su
- State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun , Jilin 130022 , People's Republic of China
| | - Xiaodong Liu
- State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun , Jilin 130022 , People's Republic of China
- University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Weilin Xu
- State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun , Jilin 130022 , People's Republic of China
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Martín-Yerga D, Costa-García A, Unwin PR. Correlative Voltammetric Microscopy: Structure-Activity Relationships in the Microscopic Electrochemical Behavior of Screen Printed Carbon Electrodes. ACS Sens 2019; 4:2173-2180. [PMID: 31353890 DOI: 10.1021/acssensors.9b01021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Screen-printed carbon electrodes (SPCEs) are widely used for electrochemical sensors. However, little is known about their electrochemical behavior at the microscopic level. In this work, we use voltammetric scanning electrochemical cell microscopy (SECCM), with dual-channel probes, to determine the microscopic factors governing the electrochemical response of SPCEs. SECCM cyclic voltammetry (CV) measurements are performed directly in hundreds of different locations of SPCEs, with high spatial resolution, using a submicrometer sized probe. Further, the localized electrode activity is spatially correlated to colocated surface structure information from scanning electron microscopy and micro-Raman spectroscopy. This approach is applied to two model electrochemical processes: hexaammineruthenium(III/II) ([Ru(NH3)6]3+/2+), a well-known outer-sphere redox couple, and dopamine (DA), which undergoes a more complex electron-proton coupled electro-oxidation, with complications from adsorption of both DA and side-products. The electrochemical reduction of [Ru(NH3)6]3+ proceeds fairly uniformly across the surface of SPCEs on the submicrometer scale. In contrast, DA electro-oxidation shows a strong dependence on the microstructure of the SPCE. By studying this process at different concentrations of DA, the relative contributions of (i) intrinsic electrode kinetics and (ii) adsorption of DA are elucidated in detail, as a function of local electrode character and surface structure. These studies provide major new insights on the electrochemical activity of SPCEs and further position voltammetric SECCM as a powerful technique for the electrochemical imaging of complex, heterogeneous, and topographically rough electrode surfaces.
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Affiliation(s)
- Daniel Martín-Yerga
- Department of Physical and Analytical Chemistry, University of Oviedo, Julián Clavería, Oviedo 33006, Spain
| | - Agustín Costa-García
- Department of Physical and Analytical Chemistry, University of Oviedo, Julián Clavería, Oviedo 33006, Spain
| | - Patrick R. Unwin
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
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Vagin MY, Sekretaryova AN, Håkansson A, Iakimov T, Ivanov IG, Syväjärvi M, Yakimova R, Lundström I, Eriksson M. Bioelectrocatalysis on Anodized Epitaxial Graphene and Conventional Graphitic Interfaces. ChemElectroChem 2019. [DOI: 10.1002/celc.201900587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mikhail Yu. Vagin
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Laboratory of Organic Electronics, Department of Science and TechnologyLinköping University 60174 Norrköping Sweden
| | - Alina N. Sekretaryova
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Department of ChemistryStanford University Stanford CA 94305-5080 USA
- Department of Chemistry'Ångström'Uppsala University Lägerhyddsvägen 1 75120 Uppsala Sweden
| | - Anna Håkansson
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Laboratory of Organic Electronics, Department of Science and TechnologyLinköping University 60174 Norrköping Sweden
| | - Tihomir Iakimov
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Graphensic AB Teknikringen 1F SE-58330 Linköping Sweden
| | - Ivan G. Ivanov
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
| | - Mikael Syväjärvi
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Graphensic AB Teknikringen 1F SE-58330 Linköping Sweden
| | - Rositsa Yakimova
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
- Graphensic AB Teknikringen 1F SE-58330 Linköping Sweden
| | - Ingemar Lundström
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
| | - Mats Eriksson
- Department of Physics, Chemistry and BiologyLinköping University 58183 Linköping Sweden
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Krivenko AG, Manzhos RA, Kochergin VK. Effect of Plasma-Assisted Electrochemical Treatment of Glassy Carbon Electrode on the Reversible and Irreversible Electrode Reactions. RUSS J ELECTROCHEM+ 2019. [DOI: 10.1134/s102319351907005x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Daviddi E, Gonos KL, Colburn AW, Bentley CL, Unwin PR. Scanning Electrochemical Cell Microscopy (SECCM) Chronopotentiometry: Development and Applications in Electroanalysis and Electrocatalysis. Anal Chem 2019; 91:9229-9237. [PMID: 31251561 DOI: 10.1021/acs.analchem.9b02091] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Scanning electrochemical cell microscopy (SECCM) has been applied for nanoscale (electro)activity mapping in a range of electrochemical systems but so far has almost exclusively been performed in controlled-potential (amperometric/voltammetric) modes. Herein, we consider the use of SECCM operated in a controlled-current (galvanostatic or chronopotentiometric) mode, to synchronously obtain spatially resolved electrode potential (i.e., electrochemical activity) and topographical "maps". This technique is first applied, as proof of concept, to study the electrochemically reversible [Ru(NH3)6]3+/2+ electron transfer process at a glassy carbon electrode surface, where the experimental data are in good agreement with well-established chronopotentiometric theory under quasi-radial diffusion conditions. The [Ru(NH3)6]3+/2+ process has also been imaged at "aged" highly ordered pyrolytic graphite (HOPG), where apparently enhanced electrochemical activity is measured at the edge plane relative to the basal plane surface, consistent with potentiostatic measurements. Finally, chronopotentiometric SECCM has been employed to benchmark a promising electrocatalytic system, the hydrogen evolution reaction (HER) at molybdenum disulfide (MoS2), where higher electrocatalytic activity (i.e., lower overpotential at a current density of 2 mA cm-2) is observed at the edge plane compared to the basal plane surface. These results are in excellent agreement with previous controlled-potential SECCM studies, confirming the viability of the technique and thereby opening up new possibilities for the use of chronopotentiometric methods for quantitative electroanalysis at the nanoscale, with promising applications in energy storage (battery) studies, electrocatalyst benchmarking, and corrosion research.
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Affiliation(s)
- Enrico Daviddi
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - Katerina L Gonos
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - Alex W Colburn
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - Cameron L Bentley
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - Patrick R Unwin
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
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Kolagatla S, Subramanian P, Schechter A. Simultaneous Mapping of Oxygen Reduction Activity and Hydrogen Peroxide Generation on Electrocatalytic Surfaces. CHEMSUSCHEM 2019; 12:2708-2714. [PMID: 30972916 DOI: 10.1002/cssc.201900656] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 04/04/2019] [Indexed: 06/09/2023]
Abstract
Electrochemical scanning probe microscopies have become valuable experimental tools, owing to their capability of capturing topographic features in addition to mapping the electrochemical activity of nanoscale oxygen reduction catalysts. However, most scanning probe techniques lack the ability to correlate topographic features with the electrochemical oxygen reduction and peroxide formation in real time. In this report, we show that it is indeed possible to construct high-resolution catalytic current maps at an electrified solid-liquid interface by placing a specially made Au-coated SiO2 Pt atomic force microscopy and scanning electrochemical microscopy (AFM-SECM) dual electrode tip approximately 4-8 nm above the reaction center. The catalytic current measured every 16 nm and high collection efficiency (≈90 %) of the reverse current of peroxide byproducts was also demonstrated with the help of the dual electrode tip. Simultaneous oxygen reduction and intermediate peroxide oxidation current mapping was demonstrated using this Au-coated SiO2 Pt probe on two model surfaces, namely highly oriented pyrolytic graphite and Pt nanoparticles (NPs) supported on a glassy carbon surface.
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Affiliation(s)
| | | | - Alex Schechter
- Department of Chemical Sciences, Ariel University, Ariel, 40700, Israel
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42
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Correlation between redox species adsorption and electron transfer kinetics of mildly oxidized graphene: A chronocoulometry and SECM study. Electrochem commun 2019. [DOI: 10.1016/j.elecom.2019.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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He L, Li C, Hamilton WA, Hong T, Tong X, Winn BL, Crow L, Bailey K, Gallego NC. Anomalous neutron scattering `halo' observed in highly oriented pyrolytic graphite. J Appl Crystallogr 2019. [DOI: 10.1107/s1600576719001110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Highly oriented pyrolytic graphite (HOPG) has been used as monochromators, analyzers and filters at neutron and X-ray scattering facilities for more than half a century. Interesting questions remain. In this work, the first observation of anomalous neutron `halo' scattering of HOPG is reported. The scattering projects a ring onto the detector with a half-cone angle of 12.4°, which surprisingly persists to incident neutron wavelengths far beyond the Bragg cutoff for graphite (6.71 Å). At longer wavelengths the ring is clearly a doublet with a splitting roughly proportional to wavelength. Sample tilting leads to the shift of the ring, which is wavelength dependent with longer wavelengths providing a smaller difference between the ring shift and the sample tilting. The ring broadens and weakens with decreasing HOPG quality. The lattice dynamics of graphite play a role in causing the scattering ring, as shown by the fact that the ring vanishes once the sample is cooled to 30 K. A possible interpretation by multiple scattering including elastic and inelastic processes is proposed.
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Nguyen J, Conca DV, Stein J, Bovo L, Howard CA, Llorente Garcia I. Magnetic control of graphitic microparticles in aqueous solutions. Proc Natl Acad Sci U S A 2019; 116:2425-2434. [PMID: 30683726 PMCID: PMC6377480 DOI: 10.1073/pnas.1817989116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Graphite is an inexpensive material with useful electrical, magnetic, thermal, and optical properties. It is also biocompatible and used universally as a substrate. Micrometer-sized graphitic particles in solution are therefore ideal candidates for novel lab-on-a-chip and remote manipulation applications in biomedicine, biophysics, chemistry, and condensed-matter physics. However, submerged graphite is not known to be amenable to magnetic manipulation, the optimal manipulation method for such applications. Here, we exploit the diamagnetism of graphite and demonstrate contactless magnetic positioning control of graphitic microflakes in diamagnetic aqueous solutions. We develop a theoretical model for magnetic manipulation of graphite microflakes and demonstrate experimentally magnetic transport of such particles over distances [Formula: see text] with peak velocities [Formula: see text] in inhomogeneous magnetic fields. We achieve fully biocompatible transport for lipid-coated graphite in NaCl aqueous solution, paving the way for previously undiscovered biomedical applications. Our results prove that micrometer-sized graphite can be magnetically manipulated in liquid media.
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Affiliation(s)
- Johnny Nguyen
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Dario Valter Conca
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Johannes Stein
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Laura Bovo
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London, London WC1H 0AJ, United Kingdom
- Department of Innovation and Enterprise, University College London, London W1T 4TJ, United Kingdom
| | - Chris A Howard
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Isabel Llorente Garcia
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom;
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Iamprasertkun P, Hirunpinyopas W, Keerthi A, Wang B, Radha B, Bissett MA, Dryfe RAW. Capacitance of Basal Plane and Edge-Oriented Highly Ordered Pyrolytic Graphite: Specific Ion Effects. J Phys Chem Lett 2019; 10:617-623. [PMID: 30672302 DOI: 10.1021/acs.jpclett.8b03523] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Carbon materials are ubiquitous in energy storage; however, many of the fundamental electrochemical properties of carbons are still not fully understood. In this work, we studied the capacitance of highly ordered pyrolytic graphite (HOPG), with the aim of investigating specific ion effects seen in the capacitance of the basal plane and edge-oriented planes of the material. A series of alkali metal cations, from Li+, Na+, K+, Rb+, and Cs+ with chloride as the counterion, were used at a fixed electrolyte concentration. The basal plane capacitance at a fixed potential relative to the potential of zero charge was found to increase from 4.72 to 9.39 μF cm-2 proceeding down Group 1. In contrast, the edge-orientated samples display capacitance ca. 100 times higher than those of the basal plane, attributed to pseudocapacitance processes associated with the presence of oxygen groups and largely independent of cation identity. This work improves understanding of capacitive properties of carbonaceous materials, leading to their continued development for use in energy storage.
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Affiliation(s)
- Pawin Iamprasertkun
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Wisit Hirunpinyopas
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Ashok Keerthi
- School of Physics and Astronomy , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Bin Wang
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Boya Radha
- School of Physics and Astronomy , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Mark A Bissett
- School of Materials , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
| | - Robert A W Dryfe
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
- National Graphene Institute , University of Manchester , Oxford Road , Manchester M13 9PL , United Kingdom
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Wu T, Alharbi A, Kiani R, Shahrjerdi D. Quantitative Principles for Precise Engineering of Sensitivity in Graphene Electrochemical Sensors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805752. [PMID: 30548684 PMCID: PMC6823930 DOI: 10.1002/adma.201805752] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/11/2018] [Indexed: 05/15/2023]
Abstract
A major difficulty in implementing carbon-based electrode arrays with high device-packing density is to ensure homogeneous and high sensitivities across the array. Overcoming this obstacle requires quantitative microscopic models that can accurately predict electrode sensitivity from its material structure. Such models are currently lacking. Here, it is shown that the sensitivity of graphene electrodes to dopamine and serotonin neurochemicals in fast-scan cyclic voltammetry measurements is strongly linked to point defects, whereas it is unaffected by line defects. Using the physics of point defects in graphene, a microscopic model is introduced that explains how point defects determine sensitivity. The predictions of this model match the empirical observation that sensitivity linearly increases with the density of point defects. This model is used to guide the nanoengineering of graphene structures for optimum sensitivity. This approach achieves reproducible fabrication of miniaturized sensors with extraordinarily higher sensitivity than conventional materials. These results lay the foundation for new integrated electrochemical sensor arrays based on nanoengineered graphene.
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Affiliation(s)
- Ting Wu
- Electrical and Computer Engineering, New York University, Brooklyn, NY, 11201, USA
| | - Abdullah Alharbi
- Electrical and Computer Engineering, New York University, Brooklyn, NY, 11201, USA
| | - Roozbeh Kiani
- Center for Neural Science, New York University, New York, NY, 10003, USA
- Neuroscience Institute, New York University Langone Medical Center, New York, NY, 10016, USA
| | - Davood Shahrjerdi
- Electrical and Computer Engineering, New York University, Brooklyn, NY, 11201, USA
- Center for Quantum Phenomena, Physics Department, New York University, New York, NY, 10003, USA
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Robinson M, Simonov AN, Zhang J, Bond AM, Gavaghan D. Separating the Effects of Experimental Noise from Inherent System Variability in Voltammetry: The [Fe(CN)6]3–/4– Process. Anal Chem 2018; 91:1944-1953. [DOI: 10.1021/acs.analchem.8b04238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Martin Robinson
- Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Alexandr N. Simonov
- School of Chemistry and the ARC Centre of Excellence for Electromaterials Science, Monash University, Clayton, Victoria 3800, Australia
| | - Jie Zhang
- School of Chemistry and the ARC Centre of Excellence for Electromaterials Science, Monash University, Clayton, Victoria 3800, Australia
| | - Alan M. Bond
- School of Chemistry and the ARC Centre of Excellence for Electromaterials Science, Monash University, Clayton, Victoria 3800, Australia
| | - David Gavaghan
- Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford OX1 3QD, United Kingdom
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Bentley CL, Edmondson J, Meloni GN, Perry D, Shkirskiy V, Unwin PR. Nanoscale Electrochemical Mapping. Anal Chem 2018; 91:84-108. [PMID: 30500157 DOI: 10.1021/acs.analchem.8b05235] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Bentley CL, Kang M, Unwin PR. Nanoscale Surface Structure–Activity in Electrochemistry and Electrocatalysis. J Am Chem Soc 2018; 141:2179-2193. [DOI: 10.1021/jacs.8b09828] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - Minkyung Kang
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Patrick R. Unwin
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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Kurapati N, Pathirathna P, Chen R, Amemiya S. Voltammetric Measurement of Adsorption Isotherm for Ferrocene Derivatives on Highly Oriented Pyrolytic Graphite. Anal Chem 2018; 90:13632-13639. [PMID: 30350623 DOI: 10.1021/acs.analchem.8b03883] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Reversible and specific adsorption of redox-active molecules from the electrolyte solution to the electrode surface is an important process and is often diagnosed by cyclic voltammetry (CV). The entire voltammogram, however, is rarely analyzed quantitatively, thereby completely missing or incorrectly extracting inherent information about the adsorption isotherm. Herein, we report CV measurements of the adsorption isotherm for ferrocene derivatives on the basal plane of highly oriented pyrolytic graphite (HOPG) to quantitatively understand the thermodynamics of ferrocene-HOPG and ferrocene-ferrocene interactions at HOPG/water interfaces. Specifically, reversible CV of (ferrocenylmethyl)trimethylammonium, ferrocenemethanol, and 1,1'-ferrocenedimethanol is obtained at 0.05-10 V/s to confirm that only reduced forms of ferrocene derivatives are adsorbed on HOPG. Finite element analysis of the entire voltammogram yields the Frumkin isotherm to separately parametrize ferrocene-HOPG and ferrocene-ferrocene interactions. Adsorption of all ferrocene derivatives is driven by similarly weak ferrocene-HOPG interactions with free energy changes of approximately -20 kJ/mol. Adsorption of ferrocenemethanol is strengthened by intermolecular hydrogen bonding, which is quantitatively represented by a free energy change of -8 kJ/mol for surface saturation and is qualitatively characterized by a pair of sharp adsorption and desorption peaks following a pair of diffusional peaks. By contrast, adsorption of (ferrocenylmethyl)trimethylammonium and 1,1'-ferrocenedimethanol remains weak because of electrostatic repulsion and weak hydrogen bonding, respectively, which correspond to the respective free energy changes of +0.7 and -3 kJ/mol for surface saturation. The unfavorable or weakly favorable intermolecular interactions broaden or narrow a diffusional peak during the forward scan, respectively, without yielding a post peak.
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Affiliation(s)
- Niraja Kurapati
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Pavithra Pathirathna
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Ran Chen
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Shigeru Amemiya
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
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