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Understanding and Controlling the Performance-Limiting Steps of Catalyst-Modified Semiconductors
Nghi P Nguyen1, Brian L Wadsworth1, Daiki Nishiori1
1School of Molecular Sciences and the Biodesign Institute Center for Applied Structural Discovery (CASD), Arizona State University, Tempe, Arizona 85287-1604, United States.
The Journal of Physical Chemistry Letters
|December 16, 2020
Summary
This study on catalyst-modified semiconductors for solar-to-fuel technology reveals two distinct mechanisms for photoelectrochemical hydrogen production, crucial for optimizing fuel-forming reactions.
Area of Science:
- Materials Science
- Electrochemistry
- Renewable Energy
Background:
- Designing effective catalyst-modified semiconductors is key for solar-to-fuel technologies.
- Understanding reaction rate limitations is essential for optimizing fuel production.
Purpose of the Study:
- To investigate GaAs semiconductors with cobaloxime catalysts for photoelectrochemical hydrogen production.
- To identify performance-limiting factors at high fuel formation rates.
Main Methods:
- Fabrication of GaAs semiconductors with polymeric coatings containing cobaloxime catalysts.
- Photoelectrochemical experiments varying bias potential, pH, illumination intensity, and scan rate.
Main Results:
- Electrodes achieved limiting current densities >20 mA cm-2 under 1-sun illumination.
- Identified two distinct hydrogen production mechanisms: proton reduction (low polarization/pH) and water reduction (high polarization/pH).
- Proton reduction was illumination-independent, while water reduction showed linear response to photon flux.
Conclusions:
- The study highlights the complex interplay of photon, electron, and substrate transport in photoelectrosynthesis.
- Demonstrates diagnostic tools for analyzing these processes.
- Provides insights into optimizing solar-to-fuel conversion efficiency.
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