1
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Au-decorated Sb 2Se 3 photocathodes for solar-driven CO 2 reduction. EES CATALYSIS 2024; 2:664-674. [PMID: 38464594 PMCID: PMC10918757 DOI: 10.1039/d3ey00222e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/05/2024] [Indexed: 03/12/2024]
Abstract
Photoelectrodes with FTO/Au/Sb2Se3/TiO2/Au architecture were studied in photoelectrochemical CO2 reduction reaction (PEC CO2RR). The preparation is based on a simple spin coating technique, where nanorod-like structures were obtained for Sb2Se3, as confirmed by SEM images. A thin conformal layer of TiO2 was coated on the Sb2Se3 nanorods via ALD, which acted as both an electron transfer layer and a protective coating. Au nanoparticles were deposited as co-catalysts via photo-assisted electrodeposition at different applied potentials to control their growth and morphology. The use of such architectures has not been explored in CO2RR yet. The photoelectrochemical performance for CO2RR was investigated with different Au catalyst loadings. A photocurrent density of ∼7.5 mA cm-2 at -0.57 V vs. RHE for syngas generation was achieved, with an average Faradaic efficiency of 25 ± 6% for CO and 63 ± 12% for H2. The presented results point toward the use of Sb2Se3-based photoelectrodes in solar CO2 conversion applications.
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2
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Effect of Single-Crystal TiO 2/Perovskite Band Alignment on the Kinetics of Electron Extraction. J Phys Chem Lett 2024; 15:2057-2065. [PMID: 38357864 PMCID: PMC10895670 DOI: 10.1021/acs.jpclett.3c03536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/02/2024] [Accepted: 02/08/2024] [Indexed: 02/16/2024]
Abstract
The kinetics of electron extraction at the electron transfer layer/perovskite interface strongly affects the efficiency of a perovskite solar cell. By combining transient absorption and time-resolved photoluminescence spectroscopy, the electron extraction process between FA0.83Cs0.17Pb(I0.83Br0.17)3 and TiO2 single crystals with different orientations of (100), (110), and (111) were probed from subpicosecond to several hundred nanoseconds. It was revealed that the band alignment between the constituents influenced the relative electron extraction process. TiO2(100) showed the fastest overall and hot electron transfer, owing to the largest conduction band and Fermi level offset compared to FA0.83Cs0.17Pb(I0.83Br0.17)3. It was found that an early electron accumulation in these systems can have an influence on the following electron extraction on the several nanosecond time scale. Furthermore, the existence of a potential barrier at the TiO2/perovskite interface was also revealed by performing excitation fluence-dependent measurements.
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3
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Renewable Syngas Generation via Low-Temperature Electrolysis: Opportunities and Challenges. ACS ENERGY LETTERS 2024; 9:288-297. [PMID: 38239720 PMCID: PMC10795495 DOI: 10.1021/acsenergylett.3c02446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/22/2024]
Abstract
The production of syngas (i.e., a mixture of CO and H2) via the electrochemical reduction of CO2 and water can contribute to the green transition of various industrial sectors. Here we provide a joint academic-industrial perspective on the key technical and economical differences of the concurrent (i.e., CO and H2 are generated in the same electrolyzer cell) and separated (i.e., CO and H2 are electrogenerated in different electrolyzers) production of syngas. Using a combination of literature analysis, experimental data, and techno-economic analysis, we demonstrate that the production of synthesis gas is notably less expensive if we operate a CO2 electrolyzer in a CO-selective mode and combine it with a separate PEM electrolyzer for H2 generation. We also conclude that by the further decrease of the cost of renewable electricity and the increase of CO2 emission taxes, such prepared renewable syngas will become cost competitive.
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4
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One-step electrodeposition of binder-containing Cu nanocube catalyst layers for carbon dioxide reduction. NANOSCALE 2023; 15:16734-16740. [PMID: 37814939 DOI: 10.1039/d3nr03834c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
To reach industrially relevant current densities in the electrochemical reduction of carbon dioxide, this process must be performed in continuous-flow electrolyzer cells, applying gas diffusion electrodes. Beyond the chemical composition of the catalyst, both its morphology and the overall structure of the catalyst layer are decisive in terms of reaction rate and product selectivity. We present an electrodeposition method for preparing coherent copper nanocube catalyst layers on hydrophobic carbon paper, hence forming gas diffusion electrodes with high coverage in a single step. This was enabled by the appropriate wetting of the carbon paper (controlled by the composition of the electrodeposition solution) and the use of a custom-designed 3D-printed electrolyzer cell, which allowed the deposition of copper nanocubes selectively on the microporous side of the carbon paper substrate. Furthermore, a polymeric binder (Capstone ST-110) was successfully incorporated into the catalyst layer during electrodeposition. The high electrode coverage and the binder content together result in an increased ethylene production rate during CO2 reduction, compared to catalyst layers prepared from simple aqueous solutions.
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5
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Comparison of TiO 2 and ZnO for Heterogeneous Photocatalytic Activation of the Peroxydisulfate Ion in Trimethoprim Degradation. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5920. [PMID: 37687613 PMCID: PMC10489049 DOI: 10.3390/ma16175920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/23/2023] [Accepted: 08/26/2023] [Indexed: 09/10/2023]
Abstract
The persulfate-based advanced oxidation process is a promising method for degrading organic pollutants. Herein, TiO2 and ZnO photocatalysts were combined with the peroxydisulfate ion (PDS) to enhance the efficiency. ZnO was significantly more efficient in PDS conversion and SO4•- generation than TiO2. For ZnO, the PDS increased the transformation rate of the trimethoprim antibiotic from 1.58 × 10-7 M s-1 to 6.83 × 10-7 M s-1. However, in the case of TiO2, the moderated positive effect was manifested mainly in O2-free suspensions. The impact of dissolved O2 and trimethoprim on PDS transformation was also studied. The results reflected that the interaction of O2, PDS, and TRIM with the surface of the photocatalyst and their competition for photogenerated charges must be considered. The effect of radical scavengers confirmed that in addition to SO4•-, •OH plays an essential role even in O2-free suspensions, and the contribution of SO4•- to the transformation is much more significant for ZnO than for TiO2. The negative impact of biologically treated domestic wastewater as a matrix was manifested, most probably because of the radical scavenging capacity of Cl- and HCO3-. Nevertheless, in the case of ZnO, the positive effect of PDS successfully overcompensates that, due to the efficient SO4•- generation. Reusability tests were performed in Milli-Q water and biologically treated domestic wastewater, and only a slight decrease in the reactivity of ZnO photocatalysts was observed.
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6
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Effects of Iron Species on Low Temperature CO 2 Electrolyzers. Angew Chem Int Ed Engl 2023:e202306503. [PMID: 37466922 DOI: 10.1002/anie.202306503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/15/2023] [Accepted: 07/17/2023] [Indexed: 07/20/2023]
Abstract
Electrochemical energy conversion devices are considered key in reducing CO2 emissions and significant efforts are being applied to accelerate device development. Unlike other technologies, low temperature electrolyzers have the ability to directly convert CO2 into a range of value-added chemicals. To make them commercially viable, however, device efficiency and durability must be increased. Although their design is similar to more mature water electrolyzers and fuel cells, new cell concepts and components are needed. Due to the complexity of the system, singular component optimization is common. As a result, the component interplay is often overlooked. The influence of Fe-species clearly shows that the cell must be considered holistically during optimization, to avoid future issues due to component interference or cross-contamination. Fe-impurities are ubiquitous, and their influence on single components is well-researched. The activity of non-noble anodes has been increased through the deliberate addition of iron. At the same time, however, Fe-species accelerate cathode and membrane degradation. Here, we interpret literature on single components to gain an understanding of how Fe-species influence low temperature CO2 electrolyzers holistically. The role of Fe-species serves to highlight the need for considerations regarding component interplay in general.
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7
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Solution Combustion Synthesis and Characterization of Magnesium Copper Vanadates. Inorg Chem 2023. [PMID: 37260199 DOI: 10.1021/acs.inorgchem.3c00452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Magnesium vanadate (MgV2O6) and its alloys with copper vanadate were synthesized via the solution combustion technique. Phase purity and solid solution formation were confirmed by a variety of experimental techniques, supported by electronic structure simulations based on density functional theory (DFT). Powder X-ray diffraction combined with Rietveld refinement, laser Raman spectroscopy, diffuse reflectance spectroscopy, and high-resolution transmission electron microscopy showed single-phase alloy formation despite the MgV2O6 and CuV2O6 end members exhibiting monoclinic and triclinic crystal systems, respectively. DFT-calculated optical band gaps showed close agreement in the computed optical bandgaps with experimentally derived values. Surface photovoltage spectroscopy, ambient-pressure photoemission spectroscopy, and Kelvin probe contact potential difference (work function) measurements confirmed a systematic variation in the optical bandgap modification and band alignment as a function of stoichiometry in the alloy composition. These data indicated n-type semiconductor behavior for all the samples which was confirmed by photoelectrochemical measurements.
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8
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Local hydrophobicity allows high-performance electrochemical carbon monoxide reduction to C 2+ products. EES CATALYSIS 2023; 1:263-273. [PMID: 37213934 PMCID: PMC10193833 DOI: 10.1039/d3ey00006k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/04/2023] [Indexed: 05/23/2023]
Abstract
While CO can already be produced at industrially relevant current densities via CO2 electrolysis, the selective formation of C2+ products seems challenging. CO electrolysis, in principle, can overcome this barrier, hence forming valuable chemicals from CO2 in two steps. Here we demonstrate that a mass-produced, commercially available polymeric pore sealer can be used as a catalyst binder, ensuring high rate and selective CO reduction. We achieved above 70% faradaic efficiency for C2+ products formation at j = 500 mA cm-2 current density. As no specific interaction between the polymer and the CO reactant was found, we attribute the stable and selective operation of the electrolyzer cell to the controlled wetting of the catalyst layer due to the homogeneous polymer coating on the catalyst particles' surface. These results indicate that sophistically designed surface modifiers are not necessarily required for CO electrolysis, but a simpler alternative can in some cases lead to the same reaction rate, selectivity and energy efficiency; hence the capital costs can be significantly decreased.
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9
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Membrane Electrode Assembly for Electrocatalytic CO2 Reduction: Principle and Application. Angew Chem Int Ed Engl 2023:e202302789. [PMID: 36971005 DOI: 10.1002/anie.202302789] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/22/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023]
Abstract
Electrocatalytic CO2 reduction reaction (CO2 RR) in membrane electrode assembly (MEA) systems is a promising technology. Gaseous CO2 can be directly transported to the cathode catalyst layer, leading to enhanced reaction rate. Meanwhile, there is no liquid electrolyte between the cathode and the anode, which can help to improve the energy efficiency of the whole system. The remarkable progress achieved recently points out the way to realize industrially relevant performance. In this review, we focus on the principles in MEA for CO2 RR, focusing on gas diffusion electrodes and ion exchange membranes. Furthermore, anode processes beyond the oxidation of water are considered. Besides, the voltage distribution is scrutinized to identify the specific losses related to the individual components. We also summarize the progress on the generation of different reduced products together with the corresponding catalysts. Finally, the challenges and opportunities are highlighted for future research.
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10
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Membrane Electrode Assembly for Electrocatalytic CO2 Reduction: Principle and Application. Angew Chem Int Ed Engl 2023. [DOI: 10.1002/ange.202302789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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11
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Systematic screening of gas diffusion layers for high performance CO 2 electrolysis. Commun Chem 2023; 6:41. [PMID: 36828885 PMCID: PMC9958001 DOI: 10.1038/s42004-023-00836-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 02/08/2023] [Indexed: 02/26/2023] Open
Abstract
Certain industrially relevant performance metrics of CO2 electrolyzers have already been approached in recent years. The energy efficiency of CO2 electrolyzers, however, is yet to be improved, and the reasons behind performance fading must be uncovered. The performance of the electrolyzer cells is strongly affected by their components, among which the gas diffusion electrode is one of the most critical elements. To understand which parameters of the gas diffusion layers (GDLs) affect the cell performance the most, we compared commercially available GDLs in the electrochemical reduction of CO2 to CO, under identical, fully controlled experimental conditions. By systematically screening the most frequently used GDLs and their counterparts differing in only one parameter, we tested the influence of the microporous layer, the polytetrafluoroethylene content, the thickness, and the orientation of the carbon fibers of the GDLs. The electrochemical results were correlated to different physical/chemical parameters of the GDLs, such as their hydrophobicity and surface cracking.
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12
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Operando characterization of continuous flow CO 2 electrolyzers: current status and future prospects. Chem Commun (Camb) 2023; 59:1395-1414. [PMID: 36655495 PMCID: PMC9894021 DOI: 10.1039/d2cc06065e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The performance of continuous-flow CO2 electrolyzers has substantially increased in recent years, achieving current density and selectivity (particularly for CO production) meeting the industrial targets. Further improvement is, however, necessary in terms of stability and energy efficiency, as well as in high-value multicarbon product formation. Accelerating this process requires deeper understanding of the complex interplay of chemical-physical processes taking place in CO2 electrolyzer cells. Operando characterization can provide these insights under working conditions, helping to identify the reasons for performance losses. Despite this fact, only relatively few studies have taken advantage of such methods up to now, applying operando techniques to characterize practically relevant CO2 electrolyzers. These studies include X-ray absorption- and Raman spectroscopy, fluorescent microscopy, scanning probe techniques, mass spectrometry, and radiography. Their objective was to characterize the catalyst structure, its microenviroment, membrane properties, etc., and relate them to the device performance (reaction rates and product distribution). Here we review the current state-of-the-art of operando methods, associated challenges, and also their future potential. We aim to motivate researchers to perform operando characterization in continuous-flow CO2 electrolyzers, to understand the reaction mechanism and device operation under practically relevant conditions, thereby advancing the field towards industrialization.
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13
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Development of a Near-Infrared Photoacoustic System for Selective, Fast, and Fully Automatized Detection of Isotopically Labeled Ammonia. Anal Chem 2022; 94:14118-14125. [PMID: 36190777 PMCID: PMC9583071 DOI: 10.1021/acs.analchem.2c01191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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Different environmental
and industrial technologies seek
for fast
and automatic ammonia detection systems, capable of the selective
measurement of the concentration of its isotopes at sub-ppm levels,
without any interference with the common contaminants. In this work,
we report the quasi-simultaneous measurement of 14NH3 and 15NH3 concentrations based on a
near-infrared diode laser-based photoacoustic system. Using a widely
tunable external cavity diode laser, four nearby wavelengths within
the range of 1531.3–1531.8 nm were optimal circumstances for
sensitive detection, while avoiding interference with water vapor.
Subsequently, a more robust distributed feedback diode laser was employed
to tune the laser wavelength on the sub-second timescale by varying
its driving current rather than using much slower temperature tuning.
The detection limit of our system is 0.15 and 0.73 ppm for 14NH3 and 15NH3 (with an accuracy
below 0.1%), respectively, and the response time is 3.5 s.
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14
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CO 2 Conversion on N-Doped Carbon Catalysts via Thermo- and Electrocatalysis: Role of C–NO x Moieties. ACS Catal 2022; 12:10127-10140. [PMID: 36033366 PMCID: PMC9397536 DOI: 10.1021/acscatal.2c01589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/21/2022] [Indexed: 11/29/2022]
Abstract
![]()
N-doped carbon (N–C) materials are increasingly
popular
in different electrochemical and catalytic applications. Due to the
structural and stoichiometric diversity of these materials, however,
the role of different functional moieties is still controversial.
We have synthesized a set of N–C catalysts, with identical
morphologies (∼27 nm pore size). By systematically changing
the precursors, we have varied the amount and chemical nature of N-functions
on the catalyst surface. The CO2 reduction (CO2R) properties of these catalysts were tested in both electrochemical
(EC) and thermal catalytic (TC) experiments (i.e., CO2 +
H2 reaction). CO was the major CO2R product
in all cases, while CH4 appeared as a minor product. Importantly,
the CO2R activity changed with the chemical composition,
and the activity trend was similar in the EC and TC scenarios. The
activity was correlated with the amount of different N-functions,
and a correlation was found for the −NOx species. Interestingly, the amount of this species decreased
radically during EC CO2R, which was coupled with the performance
decrease. The observations were rationalized by the adsorption/desorption
properties of the samples, while theoretical insights indicated a
similarity between the EC and TC paths.
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Intermittent Operation of CO 2 Electrolyzers at Industrially Relevant Current Densities. ACS ENERGY LETTERS 2022; 7:1859-1861. [PMID: 35601629 PMCID: PMC9112675 DOI: 10.1021/acsenergylett.2c00923] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 04/29/2022] [Indexed: 05/30/2023]
Abstract
We demonstrate the dynamic operation of CO2 electrolyzer cells, with a power input mimicking the output of a solar photovoltaic power plant. The zero-gap design ensured efficient intermittent operation for a week, while avoiding significant performance loss.
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Anode Catalysts in CO 2 Electrolysis: Challenges and Untapped Opportunities. ACS Catal 2022; 12:1037-1051. [PMID: 35096466 PMCID: PMC8787754 DOI: 10.1021/acscatal.1c04978] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/11/2021] [Indexed: 02/08/2023]
Abstract
The field of electrochemical carbon dioxide reduction has developed rapidly during recent years. At the same time, the role of the anodic half-reaction has received considerably less attention. In this Perspective, we scrutinize the reports on the best-performing CO2 electrolyzer cells from the past 5 years, to shed light on the role of the anodic oxygen evolution catalyst. We analyze how different cell architectures provide different local chemical environments at the anode surface, which in turn determines the pool of applicable anode catalysts. We uncover the factors that led to either a strikingly high current density operation or an exceptionally long lifetime. On the basis of our analysis, we provide a set of criteria that have to be fulfilled by an anode catalyst to achieve high performance. Finally, we provide an outlook on using alternative anode reactions (alcohol oxidation is discussed as an example), resulting in high-value products and higher energy efficiency for the overall process.
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17
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Sacrificial Agent Gone Rogue: Electron-Acceptor-Induced Degradation of CsPbBr 3 Photocathodes. ACS ENERGY LETTERS 2022; 7:417-424. [PMID: 35059504 PMCID: PMC8762702 DOI: 10.1021/acsenergylett.1c02130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/21/2021] [Indexed: 05/08/2023]
Abstract
Lead halide perovskites (LHPs) have emerged as perspective materials for light harvesting, due to their tunable band gap and optoelectronic properties. Photocatalytic and photoelectrochemical (PEC) studies, employing LHP/liquid junctions, are evolving, where sacrificial reagents are often used. In this study, we found that a frequently applied electron scavenger (TCNQ) has dual roles: while it leads to rapid electron transfer from the electrode to TCNQ, enhancing the PEC performance, it also accelerates the decomposition of the CsPbBr3 photoelectrode. The instability of the films is caused by the TCNQ-mediated halide exchange between the dichloromethane solvent and the LHP film, during PEC operation. Charge transfer and halide exchange pathways were proposed on the basis of in situ spectroelectrochemical and ex situ surface characterization methods, also providing guidance on planning PEC experiments with such systems.
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Impact of Reaction Parameters and Water Matrices on the Removal of Organic Pollutants by TiO 2/LED and ZnO/LED Heterogeneous Photocatalysis Using 365 and 398 nm Radiation. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 12:nano12010005. [PMID: 35009961 PMCID: PMC8746656 DOI: 10.3390/nano12010005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 05/05/2023]
Abstract
In this work, the application of high-power LED365nm and commercial, low-price LED398nm for heterogeneous photocatalysis with TiO2 and ZnO photocatalysts are studied and compared, focusing on the effect of light intensity, photon energy, quantum yield, electrical energy consumption, and effect of matrices and inorganic components on radical formation. Coumarin (COU) and its hydroxylated product (7-HC) were used to investigate operating parameters on the •OH formation rate. In addition to COU, two neonicotinoids, imidacloprid and thiacloprid, were also used to study the effect of various LEDs, matrices, and inorganic ions. The transformation of COU was slower for LED398nm than for LED365nm, but r07-HC/r0COU ratio was significantly higher for LED398nm. The COU mineralization rate was the same for both photocatalysts using LED365nm, but a significant difference was observed using LED398nm. The impact of matrices and their main inorganic components Cl- and HCO3- were significantly different for ZnO and TiO2. The negative effect of HCO3- was evident, however, in the case of high-power LED365nm and TiO2, and the formation of CO3•- almost doubled the r07-HC and contributes to the conversion of neonicotinoids by altering the product distribution and mineralization rate.
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19
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Local Chemical Environment Governs Anode Processes in CO 2 Electrolyzers. ACS ENERGY LETTERS 2021; 6:3801-3808. [PMID: 34796265 PMCID: PMC8593866 DOI: 10.1021/acsenergylett.1c01937] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/01/2021] [Indexed: 05/20/2023]
Abstract
A major goal within the CO2 electrolysis community is to replace the generally used Ir anode catalyst with a more abundant material, which is stable and active for water oxidation under process conditions. Ni is widely applied in alkaline water electrolysis, and it has been considered as a potential anode catalyst in CO2 electrolysis. Here we compare the operation of electrolyzer cells with Ir and Ni anodes and demonstrate that, while Ir is stable under process conditions, the degradation of Ni leads to a rapid cell failure. This is caused by two parallel mechanisms: (i) a pH decrease of the anolyte to a near neutral value and (ii) the local chemical environment developing at the anode (i.e., high carbonate concentration). The latter is detrimental for zero-gap electrolyzer cells only, but the first mechanism is universal, occurring in any kind of CO2 electrolyzer after prolonged operation with recirculated anolyte.
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20
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The Mystery of Black TiO 2: Insights from Combined Surface Science and In Situ Electrochemical Methods. ACS MATERIALS AU 2021; 1:157-168. [PMID: 34841423 PMCID: PMC8609907 DOI: 10.1021/acsmaterialsau.1c00020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Indexed: 11/28/2022]
Abstract
Titanium dioxide (TiO2) is often employed as a light absorber, electron-transporting material and catalyst in different energy and environmental applications. Heat treatment in a hydrogen atmosphere generates black TiO2 (b-TiO2), allowing better absorption of visible light, which placed this material in the forefront of research. At the same time, hydrogen treatment also introduces trap states, and the question of whether these states are beneficial or harmful is rather controversial and depends strongly on the application. We employed combined surface science and in situ electrochemical methods to scrutinize the effect of these states on the photoelectrochemical (PEC), electrocatalytic (EC), and charge storage properties of b-TiO2. Lower photocurrents were recorded with the increasing number of defect sites, but the EC and charge storage properties improved. We also found that the PEC properties can be enhanced by trap state passivation through Li+ ion intercalation in a two-step process. This passivation can only be achieved by utilizing small size cations in the electrolyte (Li+) but not with bulky ones (Bu4N+). The presented insights will help to resolve some of the controversies in the literature and also provide rational trap state engineering strategies.
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21
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Visible Light-Generated Antiviral Effect on Plasmonic Ag-TiO 2-Based Reactive Nanocomposite Thin Film. Front Bioeng Biotechnol 2021; 9:709462. [PMID: 34660548 PMCID: PMC8513738 DOI: 10.3389/fbioe.2021.709462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 09/14/2021] [Indexed: 11/13/2022] Open
Abstract
The recent coronavirus pandemic pointed out the vulnerability of humanity to new emerging infectious diseases. Experts warn that future pandemics may emerge more frequently with greater devastating effects on population health and the world economy. Although viruses are unable to propagate on lifeless surfaces, they can retain their infectivity and spread further on contact with these surfaces. The objective of our study is to analyze photoreactive composite films that exert antiviral effects upon illumination. Reactive plasmonic titanium dioxide-based polymeric nanocomposite film was prepared with a thickness of 1–1.5 µm, which produces reactive oxygen species (ROS) under visible light irradiation (λ ≥ 435 nm). These species are suitable for photooxidation of adsorbed organic molecules (e.g., benzoic acid) on the nanocomposite surface. Moreover, high molecular weight proteins are also degraded or partially oxidized in this process on the composite surface. Since the Ag0-TiO2/polymer composite film used showed excellent reactivity in the formation of OH• radicals, the photocatalytic effect on high molecular weight (M = ∼66.000 Da) bovine serum albumin (BSA) protein was investigated. Given that changes in the structure of the protein were observed upon exposure to light, we assumed virucidal effect of the illuminated photoreactive composite film. We tested this hypothesis using an airborne-transmitted herpesvirus. As a result, we obtained a drastic decrease in infection capability of the virus on the photoreactive surface compared to the control surface.
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Structural Features Dictate the Photoelectrochemical Activities of Two-Dimensional MoSe 2 and WSe 2 Nanostructures. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:7701-7710. [PMID: 33889225 PMCID: PMC8054242 DOI: 10.1021/acs.jpcc.1c01265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/19/2021] [Indexed: 06/12/2023]
Abstract
The exfoliation of layered materials into two-dimensional (2D) semiconductors creates new structural domains, for example, basal planes, defect-rich in-planes, and edge sites. These surface species affect the photoelectrochemical (PEC) performance, which in turn determines their applicability in solar energy conversion technologies. In this study, a custom-designed microdroplet cell-based spatially resolved PEC approach was employed to identify the structural parts and to measure the PEC activity of the mechanically exfoliated MoSe2 and WSe2 nanosheets for bulk, few-layer, and monolayer specimens. The PEC performance decreased with the decreasing thickness of nanoflakes, and the relative PEC activity (photo/total current) reduced by introducing more defects to the 2D flakes: 1-3% loss was found for in-plane defects and 30-40% for edge defects. While edge sites act as charge carrier recombination centers, their electrocatalytic activity is higher than that of the basal planes. The comparison of PEC activity of micromechanically and liquid phase exfoliated bulk and few-layer MoSe2 and WSe2 flakes further confirmed that the PEC performance of 2D flakes decreases with an increasing number of edge sites.
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23
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Operando cathode activation with alkali metal cations for high current density operation of water-fed zero-gap carbon dioxide electrolyzers. NATURE ENERGY 2021; 6:439-448. [PMID: 33898057 PMCID: PMC7610664 DOI: 10.1038/s41560-021-00813-w] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 03/08/2021] [Indexed: 05/04/2023]
Abstract
Continuous-flow electrolyzers allow CO2 reduction at industrially relevant rates, but long-term operation is still challenging. One reason for this is the formation of precipitates in the porous cathode from the alkaline electrolyte and the CO2 feed. Here we show that while precipitate formation is detrimental for the long-term stability, the presence of alkali metal cations at the cathode improves performance. To overcome this contradiction, we develop an operando activation and regeneration process, where the cathode of a zero-gap electrolyzer cell is periodically infused with alkali cation-containing solutions. This enables deionized water-fed electrolyzers to operate at a CO2 reduction rate matching that of those using alkaline electrolytes (CO partial current density of 420 ± 50 mA cm-2 for over 200 hours). We deconvolute the complex effects of activation and validate the concept with five different electrolytes and three different commercial membranes. Finally, we demonstrate the scalability of this approach on a multi-cell electrolyzer stack, with a 100 cm2 / cell active area.
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Abstract
Metal-halide perovskites transformed optoelectronics research and development during the past decade. They have also gained a foothold in photocatalytic and photoelectrochemical processes recently, but their sensitivity to the most commonly applied solvents and electrolytes together with their susceptibility to photocorrosion hinders such applications. Understanding the elementary steps of photocorrosion of these materials can aid the endeavor of realizing stable devices. In this Perspective, we discuss both thermodynamic and kinetic aspects of photocorrosion processes occurring at the interface of perovskite photocatalysts and photoelectrodes with different electrolytes. We show how combined in situ and operando electrochemical techniques can reveal the underlying mechanisms. Finally, we also discuss emerging strategies to mitigate photocorrosion (such as surface protection, materials and electrolyte engineering, etc.).
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25
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Hybrid FeNiOOH/α-Fe 2O 3/Graphene Photoelectrodes with Advanced Water Oxidation Performance. ADVANCED FUNCTIONAL MATERIALS 2020; 30:2002124. [PMID: 32774199 PMCID: PMC7405979 DOI: 10.1002/adfm.202002124] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/07/2020] [Indexed: 05/02/2023]
Abstract
In this study, the photoelectrochemical behavior of electrodeposited FeNiOOH/Fe2O3/graphene nanohybrid electrodes is investigated, which has precisely controlled structure and composition. The photoelectrode assembly is designed in a bioinspired manner where each component has its own function: Fe2O3 is responsible for the absorption of light, the graphene framework for proper charge carrier transport, while the FeNiOOH overlayer for facile water oxidation. The effect of each component on the photoelectrochemical behavior is studied by linear sweep photovoltammetry, incident photon-to-charge carrier conversion efficiency measurements, and long-term photoelectrolysis. 2.6 times higher photocurrents are obtained for the best-performing FeNiOOH/Fe2O3/graphene system compared to its pristine Fe2O3 counterpart. Transient absorption spectroscopy measurements reveal an increased hole-lifetime in the case of the Fe2O3/graphene samples. Long-term photoelectrolysis measurements in combination with Raman spectroscopy, however, prove that the underlying nanocarbon framework is corroded by the photogenerated holes. This issue is tackled by the electrodeposition of a thin FeNiOOH overlayer, which rapidly accepts the photogenerated holes from Fe2O3, thus eliminating the pathway leading to the corrosion of graphene.
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Recent Advances in Solar-Driven Carbon Dioxide Conversion: Expectations versus Reality. ACS ENERGY LETTERS 2020; 5:1996-2014. [PMID: 32566753 PMCID: PMC7296618 DOI: 10.1021/acsenergylett.0c00645] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/15/2020] [Indexed: 05/09/2023]
Abstract
Solar-driven carbon dioxide (CO2) conversion to fuels and high-value chemicals can contribute to the better utilization of renewable energy sources. Photosynthetic (PS), photocatalytic (PC), photoelectrochemical (PEC), and photovoltaic plus electrochemical (PV+EC) approaches are intensively studied strategies. We aimed to compare the performance of these approaches using unified metrics and to highlight representative studies with outstanding performance in a given aspect. Most importantly, a statistical analysis was carried out to compare the differences in activity, selectivity, and durability of the various approaches, and the underlying causes are discussed in detail. Several interesting trends were found: (i) Only the minority of the studies present comprehensive metrics. (ii) The CO2 reduction products and their relative amount vary across the different approaches. (iii) Only the PV+EC approach is likely to lead to industrial technologies in the midterm future. Last, a brief perspective on new directions is given to stimulate discussion and future research activity.
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Au/Pb Interface Allows the Methane Formation Pathway in Carbon Dioxide Electroreduction. ACS Catal 2020; 10:5681-5690. [PMID: 32455054 PMCID: PMC7236132 DOI: 10.1021/acscatal.0c00749] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/11/2020] [Indexed: 12/16/2022]
Abstract
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The
electrochemical conversion of carbon dioxide (CO2) to high-value
chemicals is an attractive approach to create an
artificial carbon cycle. Tuning the activity and product selectivity
while maintaining long-term stability, however, remains a significant
challenge. Here, we study a series of Au–Pb bimetallic electrocatalysts
with different Au/Pb interfaces, generating carbon monoxide (CO),
formic acid (HCOOH), and methane (CH4) as CO2 reduction products. The formation of CH4 is significant
because it has only been observed on very few Cu-free electrodes.
The maximum CH4 formation rate of 0.33 mA cm–2 was achieved when the most Au/Pb interfaces were present. In situ
Raman spectroelectrochemical studies confirmed the stability of the
Pb native substoichiometric oxide under the reduction conditions on
the Au–Pb catalyst, which seems to be a major contributor to
CH4 formation. Density functional theory simulations showed
that without Au, the reaction would get stuck on the COOH intermediate,
and without O, the reaction would not evolve further than the CHOH
intermediate. In addition, they confirmed that the Au/Pb bimetallic
interface (together with the subsurface oxygen in the model) possesses
a moderate binding strength for the key intermediates, which is indeed
necessary for the CH4 pathway. Overall, this study demonstrates how bimetallic nanoparticles
can be employed to overcome scaling relations in the CO2 reduction reaction.
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Structure-Property Relationships in Unsymmetric Bis(antiaromatics): Who Wins the Battle between Pentalene and Benzocyclobutadiene?†. J Org Chem 2020; 85:5158-5172. [PMID: 32189503 PMCID: PMC7311060 DOI: 10.1021/acs.joc.9b03119] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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According
to the currently accepted structure–property relationships,
aceno-pentalenes with an angular shape (fused to the 1,2-bond of the
acene) exhibit higher antiaromaticity than those with a linear shape
(fused to the 2,3-bond of the acene). To explore and expand the current
view, we designed and synthesized molecules where two isomeric, yet,
different, 8π antiaromatic subunits, a benzocyclobutadiene (BCB)
and a pentalene, are combined into, respectively, an angular and a
linear topology via an unsaturated six-membered ring. The antiaromatic
character of the molecules is supported experimentally by 1H NMR, UV–vis, and cyclic voltammetry measurements and X-ray
crystallography. The experimental results are further confirmed by
theoretical studies including the calculation of several aromaticity
indices (NICS, ACID, HOMA, FLU, MCI). In the case of the angular molecule,
double bond-localization within the connecting six-membered ring resulted
in reduced antiaromaticity of both the BCB and pentalene subunits,
while the linear structure provided a competitive situation for the
two unequal [4n]π subunits. We found that in
the latter case the BCB unit alleviated its unfavorable antiaromaticity
more efficiently, leaving the pentalene with strong antiaromaticity.
Thus, a reversed structure–antiaromaticity relationship when
compared to aceno-pentalenes was achieved.
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Electrodeposition of Silver Vanadate Films: A Tale of Two Polymorphs. Chemphyschem 2019; 20:2635-2646. [DOI: 10.1002/cphc.201900558] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/11/2019] [Indexed: 11/07/2022]
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30
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Correlation between the work function of Au–Ag nanoalloys and their electrocatalytic activity in carbon dioxide reduction. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.05.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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31
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Morphological Attributes Govern Carbon Dioxide Reduction on N-Doped Carbon Electrodes. JOULE 2019; 3:1719-1733. [PMID: 31417986 PMCID: PMC6686629 DOI: 10.1016/j.joule.2019.05.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/18/2019] [Accepted: 05/07/2019] [Indexed: 05/21/2023]
Abstract
The morphology of electrode materials is often overlooked when comparing different carbon-based electrocatalysts for carbon dioxide reduction. To investigate the role of morphological attributes, we studied polymer-derived, interconnected, N-doped carbon structures with uniformly sized meso or macropores, differing only in the pore size. We found that the carbon dioxide reduction selectivity (versus the hydrogen evolution reaction) increased around three times just by introducing the porosity into the carbon structure (with an optimal pore size of 27 nm). We attribute this change to alterations in the wetting and CO2 adsorption properties of the carbon catalysts. These insights offer a new platform to advance CO2 reduction performance by only morphological engineering of the electrocatalyst.
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Multilayer Electrolyzer Stack Converts Carbon Dioxide to Gas Products at High Pressure with High Efficiency. ACS ENERGY LETTERS 2019; 4:1770-1777. [PMID: 31328172 PMCID: PMC6632018 DOI: 10.1021/acsenergylett.9b01142] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 06/27/2019] [Indexed: 05/05/2023]
Abstract
Electrochemical reduction of CO2 is a value-added approach to both decrease the atmospheric emission of carbon dioxide and form valuable chemicals. We present a zero gap electrolyzer cell, which continuously converts gas phase CO2 to products without using any liquid catholyte. This is the first report of a multilayer CO2 electrolyzer stack for scaling up the electrolysis process. CO formation with partial current densities above 250 mA cm-2 were achieved routinely, which was further increased to 300 mA cm-2 (with ∼95% faradic efficiency) by pressurizing the CO2 inlet (up to 10 bar). Evenly distributing the CO2 gas among the layers, the electrolyzer operates identically to the sum of multiple single-layer electrolyzer cells. When passing the CO2 gas through the layers consecutively, the CO2 conversion efficiency increased. The electrolyzer simultaneously provides high partial current density, low cell voltage (-3.0 V), high conversion efficiency (up to 40%), and high selectivity for CO production.
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33
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Electrochemical Hole Injection Selectively Expels Iodide from Mixed Halide Perovskite Films. J Am Chem Soc 2019; 141:10812-10820. [PMID: 31259546 PMCID: PMC6624782 DOI: 10.1021/jacs.9b04568] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Halide ion mobility in metal halide perovskites remains an intriguing phenomenon, influencing their optical and photovoltaic properties. Selective injection of holes through electrochemical anodic bias has allowed us to probe the effect of hole trapping at iodide (0.9 V) and bromide (1.15 V) in mixed halide perovskite (CH3NH3PbBr1.5I1.5) films. Upon trapping holes at the iodide site, the iodide gradually gets expelled from the mixed halide film (as iodine and/or triiodide ion), leaving behind re-formed CH3NH3PbBr3 domains. The weakening of the Pb-I bond following the hole trapping (oxidation of the iodide site) and its expulsion from the lattice in the form of iodine provided further insight into the photoinduced segregation of halide ions in mixed halide perovskite films. Transient absorption spectroscopy revealed that the iodide expulsion process leaves a defect-rich perovskite lattice behind as charge carrier recombination in the re-formed lattice is greatly accelerated. The selective mobility of iodide species provides insight into the photoinduced phase segregation and its implication in the stable operation of perovskite solar cells.
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34
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Role of f Electrons in the Optical and Photoelectrochemical Behavior of Ca(La 1- xCe x) 2S 4 (0 ≤ x ≤ 1). Inorg Chem 2019; 58:4553-4560. [PMID: 30888802 DOI: 10.1021/acs.inorgchem.9b00062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study focuses on a solid solution series, Ca(La1- xCe x)2S4 (0 ≤ x ≤ 1), where the f electron density is absent in CaLa2S4 and is progressively increased until it is maximized in CaCe2S4. Correspondingly, these samples, synthesized by a sealed ampule method, showed progressive variations in color ranging from gray for CaLa2S4 to orange-red for CaCe2S4. The crystal structural nuances of both the end members and three solid solutions with x = 0.25, 0.50, and 0.75 were established with the complementary use of synchrotron X-ray diffraction and neutron scattering. Interestingly, these data were consistent with a two-phase composition centered around each nominal solid solution stoichiometry. Optical characterization via diffuse reflectance spectroscopy and Tauc analyses showed a shrinking of the energy band gap (from the UV to vis range) when Ce was progressively introduced into the host CaLa2S4 structure. These data were in concert with electronic band structure calculations, using density functional theory, which showed the progressive formation of an intermediate f band when Ce was introduced intro the structure. Photoelectrochemical measurements in an aqueous redox electrolyte, as well as surface photovoltage and Kelvin probe measurements, revealed all samples to be n-type semiconductors. The valence and conduction band edge positions of the end members and the three solid solutions could be mapped, on both the redox and vacuum reference energy scales, by combining these measurements with the optical data.
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35
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Tuning the Excited-State Dynamics of CuI Films with Electrochemical Bias. ACS ENERGY LETTERS 2019; 4:702-708. [PMID: 30882041 PMCID: PMC6413481 DOI: 10.1021/acsenergylett.9b00182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 02/13/2019] [Indexed: 05/27/2023]
Abstract
Owing to its high hole conductivity and ease of preparation, CuI was among the first inorganic hole-transporting materials that were introduced early on in metal halide perovskite solar cells, but its full potential as a semiconductor material is still to be realized. We have now performed ultrafast spectroelectrochemical experiments on ITO/CuI electrodes to show the effect of applied bias on the excited-state dynamics in CuI. Under operating conditions, the recombination of excitons is dependent on the applied bias, and it can be accelerated by decreasing the potential from +0.6 to -0.1 V vs Ag/AgCl. Prebiasing experiments show the persistent and reversible "memory" effect of electrochemical bias on charge carrier lifetimes. The excitation of CuI in a CuI/CsPbBr3 film provides synergy between both CuI and CsPbBr3 in dictating the charge separation and recombination.
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36
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Optoelectronic Properties of CuI Photoelectrodes. J Phys Chem Lett 2019; 10:259-264. [PMID: 30601661 PMCID: PMC6340132 DOI: 10.1021/acs.jpclett.8b03242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 12/17/2018] [Indexed: 06/01/2023]
Abstract
Detailed mechanistic understanding of the optoelectronic features is a key factor in designing efficient and stable photoelectrodes. In situ spectroelectrochemical methods were employed to scrutinize the effect of trap states on the optical and electronic properties of CuI photoelectrodes and to assess their stability against (photo)electrochemical corrosion. The excitonic band in the absorption spectrum and the Raman spectral features were directly influenced by the applied bias potential. These spectral changes exhibit a good correlation with the alterations observed in the charge-transfer resistance. Interestingly, the population and depopulation of the trap states, which are responsible for the changes in both the optical and electronic properties, occur in a different potential/energy regime. Although cathodic photocorrosion of CuI is thermodynamically favored, this process is kinetically hindered, thus providing good stability in photoelectrochemical operation.
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37
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Composition-Dependent Optical and Photoelectrochemical Behavior of Antimony Oxide Iodides. JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2019. [DOI: 10.1149/2.0311905jes] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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38
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Electrodeposition of Hole-Transport Layer on Methylammonium Lead Iodide Film: A Strategy To Assemble Perovskite Solar Cells. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2018; 30:4202-4206. [PMID: 30022806 PMCID: PMC6046219 DOI: 10.1021/acs.chemmater.8b01521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/12/2018] [Indexed: 06/08/2023]
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39
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Photoelectrochemical Behavior of PEDOT/Nanocarbon Electrodes: Fundamentals and Structure-Property Relationships. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:13682-13690. [PMID: 29983842 PMCID: PMC6028895 DOI: 10.1021/acs.jpcc.8b00145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/15/2018] [Indexed: 05/13/2023]
Abstract
In this study, we investigated the photoelectrochemical behavior of poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) and PEDOT/graphene nanocomposite photoelectrodes for the first time. Electrodeposition allowed control of both the composition and the morphology (as demonstrated by both transmission and scanning electron microscopy images) and also ensured an intimate contact between the PEDOT film and the nanocarbon scaffold. The effect of CNT and graphene on the photoelectrochemical behavior of the nanocomposite samples was studied by linear sweep photovoltammetry, incident photon-to-charge-carrier conversion efficiency measurements, and long-term photoelectrolysis coupled with gas-chromatographic product analysis. We demonstrated that the nanocarbon framework facilitated efficient charge carrier transport, resulting in a 4-fold increase in the measured photocurrents for the PEDOT/CNT electrode, compared to the bare PEDOT counterpart. The presented results contribute to the better understanding of the enhanced photoelectrochemical behavior of organic semiconductor/nanocarbon electrode assemblies and might encourage other researchers to study these intriguing hybrid materials further.
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40
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Photoelectrochemistry of semiconductors at the nanoscale from fundamental aspects to practical applications (ITM/S 2017): Foreword. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.03.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Electrochemical Reduction of Carbon Dioxide on Nitrogen-Doped Carbons: Insights from Isotopic Labeling Studies. ACS ENERGY LETTERS 2018; 3:722-723. [PMID: 29552639 PMCID: PMC5848144 DOI: 10.1021/acsenergylett.8b00212] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 02/19/2018] [Indexed: 05/30/2023]
Abstract
Isotopic labeling experiments were performed to better understand the electrochemical reduction of carbon dioxide on nitrogen-doped porous carbon electrodes. By using nonequilibrated solutions of selectively labeled initial carbon sources (i.e., 13CO2 and H13CO3-), bicarbonate anion was identified as the predominant source of the carbon monoxide reduction product.
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42
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Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2018; 30:561-569. [PMID: 29503507 PMCID: PMC5828706 DOI: 10.1021/acs.chemmater.7b04321] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/01/2017] [Indexed: 05/20/2023]
Abstract
The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MAPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.
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Abstract
In this communication, we demonstrate that polyaniline, the very first example of an organic semiconductor, is a promising photocathode material for the conversion of carbon dioxide (CO2) to alcohol fuels. CO2 is a greenhouse gas; thus using solar energy to convert CO2 to transportation fuels (such as methanol or ethanol) is a value-added approach to simultaneous generation of alternative fuels and environmental remediation of carbon emissions. Insights into its unique behavior obtained from photoelectrochemical measurements and adsorption studies, together with spectroscopic data, are presented. Through a comparative study involving various conducting polymers, a set of criteria is developed for an organic semiconductor to function as a photocathode for generation of solar fuels from CO2.
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44
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Modulation of Charge Recombination in CsPbBr 3 Perovskite Films with Electrochemical Bias. J Am Chem Soc 2018; 140:86-89. [PMID: 29129051 PMCID: PMC5765538 DOI: 10.1021/jacs.7b10958] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Indexed: 12/20/2022]
Abstract
The charging of a mesoscopic TiO2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr3 films deposited on a mesoscopic TiO2 film, we have succeeded in probing the influence of electrochemical bias on the charge carrier recombination process. The transient absorption spectroscopy experiments conducted at different applied potentials indicate a decrease in the charge carrier lifetimes of CsPbBr3 as we increase the potential from -0.6 to +0.6 V vs Ag/AgCl. The charge carrier lifetime increased upon reversing the applied bias, thus indicating the reversibility of the photoresponse to charging effects. The ultrafast spectroelectrochemical experiments described here offer a convenient approach to probe the charging effects in perovskite solar cells.
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45
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Microstructuration of poly(3-hexylthiophene) leads to bifunctional superhydrophobic and photoreactive surfaces. Chem Commun (Camb) 2018; 54:650-653. [DOI: 10.1039/c7cc07671a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Schematic representation and a preparation route for the poly(3-hexylthiophene) conducting polymer film having both superhydrophobic and visible-light active photocatalytic properties.
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46
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Nitridation of one-dimensional tungsten oxide nanostructures: Changes in structure and photoactivity. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.10.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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47
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Electrosynthesis and photoelectrochemical properties of polyaniline/SiC nanohybrid electrodes. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.10.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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48
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49
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Photoelectrochemistry by Design: Tailoring the Nanoscale Structure of Pt/NiO Composites Leads to Enhanced Photoelectrochemical Hydrogen Evolution Performance. THE JOURNAL OF PHYSICAL CHEMISTRY C 2017; 121:12148-12158. [PMID: 28620447 PMCID: PMC5467181 DOI: 10.1021/acs.jpcc.7b00429] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/04/2017] [Indexed: 11/29/2022]
Abstract
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Photoelectrochemical
hydrogen evolution is a promising avenue to
store the energy of sunlight in the form of chemical bonds. The recent
rapid development of new synthetic approaches enables the nanoscale
engineering of semiconductor photoelectrodes, thus tailoring their
physicochemical properties toward efficient H2 formation.
In this work, we carried out the parallel optimization of the morphological
features of the semiconductor light absorber (NiO) and the cocatalyst
(Pt). While nanoporous NiO films were obtained by electrochemical
anodization, the monodisperse Pt nanoparticles were synthesized using
wet chemical methods. The Pt/NiO nanocomposites were characterized
by XRD, XPS, SEM, ED, TEM, cyclic voltammetry, photovoltammetry, EIS,
etc. The relative enhancement of the photocurrent was demonstrated
as a function of the nanoparticle size and loading. For mass-specific
surface activity the smallest nanoparticles (2.0 and 4.8 nm) showed
the best performance. After deconvoluting the trivial geometrical
effects (stemming from the variation of Pt particle size and thus
the electroactive surface area), however, the intermediate particle
sizes (4.8 and 7.2 nm) were found to be optimal. Under optimized conditions,
a 20-fold increase in the photocurrent (and thus the H2 evolution rates) was observed for the nanostructured Pt/NiO composite,
compared to the benchmark nanoparticulate NiO film.
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Enhanced Photoelectrochemical Performance of Cuprous Oxide/Graphene Nanohybrids. J Am Chem Soc 2017; 139:6682-6692. [PMID: 28460518 PMCID: PMC5456415 DOI: 10.1021/jacs.7b01820] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 11/29/2022]
Abstract
Combination of an oxide semiconductor with a highly conductive nanocarbon framework (such as graphene or carbon nanotubes) is an attractive avenue to assemble efficient photoelectrodes for solar fuel generation. To fully exploit the possible synergies of the hybrid formation, however, precise knowledge of these systems is required to allow rational design and morphological engineering. In this paper, we present the controlled electrochemical deposition of nanocrystalline p-Cu2O on the surface of different graphene substrates. The developed synthetic protocol allowed tuning of the morphological features of the hybrids as deduced from electron microscopy. (Photo)electrochemical measurements (including photovoltammetry, electrochemical impedance spectroscopy, photocurrent transient analysis) demonstrated better performance for the 2D graphene containing photoelectrodes, compared to the bare Cu2O films, the enhanced performance being rooted in suppressed charge carrier recombination. To elucidate the precise role of graphene, comparative studies were performed with carbon nanotube (CNT) films and 3D graphene foams. These studies revealed, after allowing for the effect of increased surface area, that the 3D graphene substrate outperformed the other two nanocarbons. Its interconnected structure facilitated effective charge separation and transport, leading to better harvesting of the generated photoelectrons. These hybrid assemblies are shown to be potentially attractive candidates in photoelectrochemical energy conversion schemes, namely CO2 reduction.
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