Surface Interrogation Scanning Electrochemical Microscopy for a Photoelectrochemical Reaction: Water Oxidation on a
Jae Young Kim1,2, Hyun S Ahn3, Allen J Bard1
1Center for Electrochemistry, Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States.
Abstract:
To understand the pathway of a photoelectrochemical (PEC) reaction, quantitative knowledge of reaction intermediates is important. We describe here surface interrogation scanning electrochemical microscopy for this purpose (PEC SI-SECM), where a light pulse to a photoactive semiconductor film at a given potential generates intermediates that are then analyzed by a tip generated titrant at known times after the light pulse. The improvements were demonstrated for photoelectrochemical water oxidation (oxygen evolution) reaction on a hematite surface. The density of photoactive sites, proposed to be Fe4+ species, on a hematite surface was successfully quantified, and the photoelectrochemical water oxidation reaction dynamics were elucidated by time-dependent redox titration experiments. The new configuration of PEC SI-SECM should find expanded usage to understand and investigate more complicated PEC reactions with other materials.
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