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Semiconductor-Electrocatalyst Interfaces: Theory, Experiment, and Applications in Photoelectrochemical Water
Michael R Nellist1, Forrest A L Laskowski1, Fuding Lin1
1Department of Chemistry and Biochemistry, University of Oregon , Eugene, Oregon 97403, United States.
Accounts of Chemical Research
|April 2, 2016
Summary
Understanding the semiconductor-electrocatalyst interface is crucial for photoelectrochemical energy conversion. This study reveals that electrolyte-permeable catalysts form adaptive junctions, enhancing photovoltage and efficiency for systems like water splitting.
Area of Science:
- Materials Science
- Electrochemistry
- Renewable Energy
Background:
- Semiconductor electrodes coated with electrocatalysts are vital for photoelectrochemical energy conversion.
- Optimizing these systems is hindered by a poor understanding of the semiconductor-electrocatalyst (sem|cat) interface.
- This interface is critical for separating photoexcited charge carriers and driving photochemical reactions like water splitting.
Purpose of the Study:
- To elucidate the microscopic processes and material parameters governing interfacial electron transfer.
- To investigate the properties of transition-metal oxyhydroxide electrocatalysts, specifically Ni(Fe)OOH, for efficient oxygen evolution.
- To differentiate between "adaptive" and "buried" junction behaviors based on catalyst properties.
Main Methods:
- Utilized numerical simulations to explain the behavior of composite systems and charge-transfer kinetics.
- Developed dual-working-electrode (DWE) photoelectroelectrochemistry to measure electrocatalyst potential during operation.
- Investigated electrolyte-permeable (Ni(Fe)OOH) and electrolyte-impermeable (IrOx) catalysts.
Main Results:
- Electrolyte-permeable catalysts form "adaptive" junctions where interface energetics change with catalyst potential.
- Electrolyte-impermeable catalysts form "buried" junctions with stable interface physics.
- Adaptive junctions, formed by soft-deposited catalysts, yield higher photovoltages and efficiencies compared to buried junctions.
Conclusions:
- The type of semiconductor-electrocatalyst junction significantly impacts photoelectrode performance.
- Adaptive junctions offer a design principle for improved photoelectrochemical devices.
- Further theoretical and experimental work is needed to optimize catalyst contacts and account for surface states.
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