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A method is presented to quantitatively analyze the reduction of vanadium(V) to vanadium(IV) over two flat carbon substrates (glassy carbon and graphite foil) using the feedback mode of scanning electrochemical microscopy. A pulse profile is validated and applied during approach curve experiments of a 10 μm Pt microelectrode. By fitting the approach curve data, electron transfer constants are calculated for various potentials and k0 is extracted from the corresponding Tafel plot. Furthermore, surface functional groups were introduced to the carbon substrates by acid treatment; however, kinetic parameters of the sluggish reduction reaction were only influenced to a minor extent. Finally, the same approach, combined with in situ‐Raman microscopy, is applied to a single graphene layer using a 2.7 μm Pt microelectrode. In this case, increased activity for both, the vanadium(V) reduction and vanadium(IV) oxidation reaction, was found close to the graphene edge sites by means of electrochemical microscopy for the first time. [ABSTRACT FROM AUTHOR]

In this work, the simultaneous investigation of a single cuprous oxide microcrystal towards CO2 electroreduction (CRR, CO2 reduction reaction) by using Raman microscopy and scanning electrochemical microscopy (SECM) is shown. Cu2O microcrystals were electrochemically crystallized on an indium‐doped tin oxide‐substrate (ITO). Structural changes of the Cu2O microcrystal are observed in situ by Raman microcopy, which indicates their fast conversion into elemental Cu at low overpotentials. Simultaneously, detection of products of the CO2 reduction is carried out electrochemically using the sample‐generation tip‐collection mode (SG/TC) of SECM and formate ions are the main product of CRR, as detected by a 10 μm Pt ultramicroelectrode (UME). Thus, with our approach, the very beginning of the CRR (onset potential), potential‐dependent product formation as well as structural changes in the catalyst can be precisely investigated. [ABSTRACT FROM AUTHOR]

Keywords: carbon dioxide reduction; cuprous oxide; scanning electrochemical microscopy; Raman microscopy; in situ characterization EN carbon dioxide reduction cuprous oxide scanning electrochemical microscopy Raman microscopy in situ characterization 1 1 1 02/21/22 20220211 NES 220211 B The Cover Feature b illustrates the simultaneous probing of a cuprous oxide microcrystal by Raman and Scanning Electrochemical Microscopy (SECM) during CO SB 2 sb electro-reduction. Cover Feature: Probing Individual Cuprous Oxide Microcrystals towards Carbon Dioxide Reduction by using In Situ Raman-coupled Scanning Electrochemical Microscopy (ChemElectroChem 3/2022) Carbon dioxide reduction, cuprous oxide, scanning electrochemical microscopy, Raman microscopy, in situ characterization. [Extracted from the article]