期刊
ANALYTICAL CHEMISTRY
卷 93, 期 48, 页码 15886-15896出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.1c02598
关键词
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资金
- National Science Foundation (NSF) [CBET-2113505]
- Marilyn Williams Elmore and John Durr Elmore Professor fellowship
- Alabama Transportation Institute
The study introduces a new transparent UME-SECM method for investigating semiconductor PEC activities, capable of quantifying the interfacial charge-transfer rates and photocatalytic water oxidation reactions. This method provides insights into potential-dependent PEC water oxidation reaction mechanisms and quantitative analysis of photocurrent contributions.
Scanning electrochemical microscopy (SECM) has been extensively applied to the electrochemical analysis of the surfaces and interfaces of a photoelectrochemical (PEC) system. A semiconductor photoelectrode with a well-defined geometry and active surface area comparable to SECM's tip is highly desired for accurately quantifying interfacial charge-transfer activities and photoelectrochemically generated redox species, where the broadening effects due to the mass transfer gradient and nonlocal electron transfer at a planar semiconductor surface can be minimized. Here, we present a newly developed platform as a SECM substrate for investigating semiconductor PEC activities, which is based on a transparent ultramicroelectrode (UME) fabricated by using two-step photolithographic patterning and ion milling methods. This transparent UME with a 25 mu m recessed disk shape is fully characterized with SECM for quantifying the interfacial charge-transfer rates of IrCl62-/IrCl63- by comparing with theoretical results from finite element simulations in COMSOL Multiphysics. When coated with TiO2 nanorods as a model semiconductor material, the transparent UME can be used to quantify the catalytic PEC water oxidation in a feedback mode of SECM by sampling tip and substrate current signals simultaneously. This transparent UME-SECM study provides insights into the potential-dependent PEC water oxidation reaction mechanism and the quantitative analysis of photocurrent contributions from water oxidation and the SECM tip-generated redox mediator. The transparent UME-SECM method can be potentially expanded to other SECM operation modes such as surface interrogation for understanding the dynamics of the electrode surfaces and interfaces of a PEC system.
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