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Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids
Published on: August 23, 2012
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Reactive Chemical Environments Control Charge Carrier Selectivity and Photovoltage at Nanoparticle
Ahmet Sert1,2, Aarti Mathur1,2, Suljo Linic1,2
1Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
Journal of the American Chemical Society
|August 18, 2025
Summary
The local chemical environment dynamically tunes charge transfer at platinum/silicon junctions in solar water splitting. Molecular adsorption creates interfacial dipoles, controlling the electronic structure and improving photoelectrode performance.
Area of Science:
- Materials Science
- Electrochemistry
- Photocatalysis
Background:
- Interfacial charge transfer is critical for photo(electro)catalyst performance.
- The impact of the reactive environment on unburied electrocatalyst/semiconductor (EC/SC) junctions is not well understood.
- Nanoparticle EC on SC (np-EC/SC) interfaces are directly exposed to reacting molecules.
Purpose of the Study:
- To investigate the dynamic, chemically driven modulation of charge transfer at platinum/p-silicon (Pt/p-Si) interfaces under solar water splitting conditions.
- To elucidate the mechanism by which the local reaction environment influences interfacial properties and charge transfer.
- To explore strategies for optimizing nanoscale photoelectrode architectures for solar fuel production.
Main Methods:
- Utilized Pt/p-Si interfaces as a model system for unburied EC/SC junctions.
- Investigated the effects of molecular adsorption (H2 and O2) on interfacial properties.
- Analyzed the formation of interfacial dipoles and their impact on work function and junction behavior.
- Characterized the role of a spontaneously evolved SiO_x interlayer in charge transfer.
Main Results:
- Molecular adsorption of H2 and O2 induces interfacial dipoles on Pt nanoparticles, tuning their work function.
- This tuning shifts the Pt/p-Si junction from Ohmic to rectifying behavior by modulating the Schottky barrier height.
- Environment-responsive modulation of the Schottky barrier height governs charge carrier selectivity, overriding the pinch-off effect.
- A thin SiO_x interlayer facilitates tunneling and suppresses recombination, enhancing interfacial control.
Conclusions:
- Catalytic surface chemistry dynamically controls electronic structure and photovoltage in nanoscale photoelectrodes.
- Environment-driven modulation of interfacial dipoles offers a new design strategy for high-efficiency solar fuel systems.
- Understanding and controlling interfacial chemistry is key to advancing photo(electro)catalyst design.
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