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Wu H, Li G, Hou J, Sotthewes K. Probing surface properties of organic molecular layers by scanning tunneling microscopy. Adv Colloid Interface Sci 2023; 318:102956. [PMID: 37393823 DOI: 10.1016/j.cis.2023.102956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 07/04/2023]
Abstract
In view of the relevance of organic thin layers in many fields, the fundamentals, growth mechanisms, and dynamics of thin organic layers, in particular thiol-based self-assembled monolayers (SAMs) on Au(111) are systematically elaborated. From both theoretical and practical perspectives, dynamical and structural features of the SAMs are of great intrigue. Scanning tunneling microscopy (STM) is a remarkably powerful technique employed in the characterization of SAMs. Numerous research examples of investigation about the structural and dynamical properties of SAMs using STM, sometimes combined with other techniques, are listed in the review. Advanced options to enhance the time resolution of STM are discussed. Additionally, we elaborate on the extremely diverse dynamics of various SAMs, such as phase transitions and structural changes at the molecular level. In brief, the current review is expected to supply a better understanding and novel insights regarding the dynamical events happening in organic SAMs and how to characterize these processes.
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Affiliation(s)
- Hairong Wu
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China.
| | - Genglin Li
- College of Science, China University of Petroleum-Beijing, Beijing 102249, China
| | - Jirui Hou
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, the Netherlands.
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Zhiani M, Taghiabadi MM, Bagherabadi MH. Optimization of Ni-Mo-Coated Stainless Steel as a High-Performance Cathode in Alkaline Water Electrolysis. Electrocatalysis (N Y) 2023. [DOI: 10.1007/s12678-023-00810-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Altunbaş Şahin E. The use of avocado seed self‐assembly monolayer films for the catalysis of methanol electrooxidation reaction. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ece Altunbaş Şahin
- Property Protection and Security Department Bingol University, Genç Vocational School, Civil Defense and Firefighting Program Bingol Turkey
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Hermann JM, Müller H, Daccache L, Adler C, Keller S, Metzler M, Jacob T, Kibler LA. Formic acid oxidation reaction on Au(111) electrodes modified with 4-mercaptopyridine SAM. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hydrogen Peroxide Oxidation Reaction on a 4-Mercaptopyridine Self-Assembled Monolayer on Au(111) Metallized by Platinum Nanoislands. Electrocatalysis (N Y) 2021. [DOI: 10.1007/s12678-021-00647-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractA systematic investigation of the hydrogen peroxide oxidation reaction (HPOR) in phosphate buffer (pH = 7.3) on an Au(111) single crystal modified with a 4-mercaptopyridine self-assembled monolayer (SAM) has been conducted before and after metallization with Pt. While bare Au(111) shows considerable electrocatalytic activity towards the HPOR, the inhibition of the oxidation reaction after modification with the SAM implies that adsorbed 4-mercaptopyridine molecules do not catalyze the HPOR. However, SAM-modified Au(111) recovers catalytic activity for the HPOR already after a single metallization step fabricating Pt islands on-top. Hydrogen peroxide (HP) may then either react at the (non-metallic) Pt nanoislands or on reactivated Au sites, made accessible by structural changes of the SAM induced by the metallization. The shape of the voltammetric profiles for the HPOR on repeatedly metallized SAMs suggests that the contribution of Au to the total current density gradually diminishes with increasing Pt coverage while the contribution of the Pt islands increases. The electrochemical behavior is dominated by the Pt islands at a coverage of 0.5 ML obtained by three subsequent metallization steps.
Graphical abstract
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Fang JS, Yang TM, Pan YC, Lai GY, Cheng YL, Chen GS. Chemical-Structure Evolution Model for the Self-Assembling of Amine-Terminated Monolayers on Nanoporous Carbon-Doped Organosilicate in Tightly Controlled Environments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15153-15161. [PMID: 33270454 DOI: 10.1021/acs.langmuir.0c02801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Amine-terminated self-assembled monolayers are molecular nanolayers, typically formed via wet-chemical solution on specific substrates for precision surface engineering or interface modification. However, homogeneous assembling of a highly ordered monolayer by the facile, wet method is rather tricky because it involves process parameters, such as solvent type, molecular concentration, soaking time and temperature, and humidity level. Here, we select 3-aminopropyltrimethoxysilane (APTMS) as a model molecule of aminosilane for the silanization of nanoporous carbon-doped organosilicate (p-SiOCH) under tightly controlled process environments. Surface mean roughness (Ra) and the water contact angle (θ) of the p-SiOCH layers upon silanization at a 10% humidity-controlled environment behave similarly and follow a three-stage evolution: a leap to a maximum at 15 min for Ra (from 0.227 to 0.411 nm) and θ (from 25 to 86°), followed by a gradual decrease to 0.225 nm and 69o, finally leveling off at the above values (>60 min). The -NH3+ fraction indicating monolayer disorientation evolves in a similar fashion. The fully grown monolayer is highly oriented yielding an unprecedented low -NH3+ fraction of 0.08 (and 0.92 of upright -NH2 groups). However, while having a similar thickness of approximately 1.4 ± 0.1 nm, the molecular layers grown at 30% relative humidity exhibit a significantly elevated -NH3+ fraction of 0.42, indicating that controlling the humidity is vital to the fabrication of highly oriented APTMS molecular layers. A bonding-structure evolution model, as distinct from those offered previously, is proposed and discussed.
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Affiliation(s)
- Jau-Shiung Fang
- Department of Materials Science and Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan
| | - Tzu-Ming Yang
- Department of Materials Science and Engineering, Feng Chia University, Seatwen, Taichung 40724, Taiwan
| | - Yen-Chang Pan
- Department of Materials Science and Engineering, Feng Chia University, Seatwen, Taichung 40724, Taiwan
| | - Guan-Yu Lai
- Department of Materials Science and Engineering, Feng Chia University, Seatwen, Taichung 40724, Taiwan
| | - Yi-Lung Cheng
- Department of Electrical Engineering, National Chi-Nan University, Puli, Nantou 54561, Taiwan
| | - Giin-Shan Chen
- Department of Materials Science and Engineering, Feng Chia University, Seatwen, Taichung 40724, Taiwan
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Yao Z, Buck M, Bühl M. Density Functional Theory Study of Pd Aggregation on a Pyridine-Terminated Self-Assembled Monolayer. Chemistry 2020; 26:10555-10563. [PMID: 32428284 PMCID: PMC7497155 DOI: 10.1002/chem.202001242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/13/2020] [Indexed: 11/08/2022]
Abstract
By using density functional theory calculations, the initial steps towards Pd metal cluster formation on a pyridine-terminated self-assembled monolayer (SAM) consisting of 3-(4-(pyridine-4-yl)phenyl)propane-1-thiol on an Au(1 1 1) surface are investigated. Theoretical modelling allows the investigation of structural details of the SAM surface and the metal/SAM interface at the atomic level, which is essential for elucidating the nature of Pd-SAM and Pd-Pd interactions at the liquid/solid interface and gaining insight into the mechanism of metal nucleation in the initial stage of electrodeposition. The structural flexibility of SAM molecules was studied first and the most stable conformation was identified, planar molecules in a herringbone packing, as the model for Pd adsorption. Two binding sites are found for Pd atoms on the pyridine end group of the SAM. The strong interaction between Pd atoms and pyridines illustrates the importance of SAM functionalisation in the metal nucleation process. Consistent with an energetic driving force of approximately -0.3 eV per Pd atom towards Pd aggregation suggested by static calculations, a spontaneous Pd dimerisation is observed in ab initio molecular dynamic studies of the system. Nudged elastic band calculations suggest a potential route with a low energy barrier of 0.10 eV for the Pd atom diffusion and then dimerisation on top of the SAM layer.
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Affiliation(s)
- Zhen Yao
- EaStCHEM School of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
| | - Manfred Buck
- EaStCHEM School of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
| | - Michael Bühl
- EaStCHEM School of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
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She Z, Yao Z, Ménard H, Tobish S, Lahaye D, Champness NR, Buck M. Coordination controlled electrodeposition and patterning of layers of palladium/copper nanoparticles on top of a self-assembled monolayer. NANOSCALE 2019; 11:13773-13782. [PMID: 31305824 DOI: 10.1039/c9nr03927a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A scheme for the generation of bimetallic nanoparticles is presented which combines electrodeposition of one type of metal, coordinated to a self-assembled monolayer (SAM), with another metal deposited from the bulk electrolyte. In this way PdCu nanoparticles are generated by initial complexation of Pd2+ to a SAM of 3-(4-(pyridine-4-yl)phenyl)propane-1-thiol (PyP3) on Au/mica and subsequent reduction in an acidic aqueous CuSO4 electrolyte. Cyclic voltammetry reveals that the onset of Cu deposition is triggered by Pd reduction. Scanning tunneling microscopy (STM) shows that layers of connected particles are formed with an average thickness of less than 3 nm and lateral dimensions of particles in the range of 2 to 5 nm. In X-ray photoelectron spectra a range of binding energies for the Pd 3d signal is observed whereas the Cu 2p signal appears at a single binding energy, even though chemically different Cu species are present: normal and more noble Cu. Up to three components are seen in the N 1s signal, one originating from protonated pyridine moieties, the others reflecting the SAM-metal interaction. It is suggested that the coordination controlled electrodeposition yields layers of particles composed of a Pd core and a Cu shell with a transition region of a PdCu alloy. Deposited on top of the PyP3 SAM, the PdCu particles exhibit weak adhesion which is exploited for patterning by selective removal of particles employing scanning probe techniques. The potential for patterning down to the sub-10 nm scale is demonstrated. Harnessing the deposition contrast between native and PdCu loaded PyP3 SAMs, structures thus created can be developed into patterned continuous layers.
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Affiliation(s)
- Zhe She
- EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST, UK.
| | - Zhen Yao
- EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST, UK.
| | - Hervé Ménard
- Leverhulme Research Centre for Forensic Science, University of Dundee, Dundee, DD1 4HN, UK
| | - Sven Tobish
- Drochaid Research Services, North Haugh, St. Andrews, KY16 9ST, UK
| | - Dorothée Lahaye
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Neil R Champness
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Manfred Buck
- EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST, UK.
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