Researchers Demonstrate Wavelength-Dependent Control of CO2 Reduction Selectivity Using Plasmonic Catalysts
Scientists used advanced microscopy techniques to show that different wavelengths of light can selectively drive different chemical products from CO2 reduction on plasmonic gold catalysts. The study found that shorter wavelengths (460-560 nm) favor carbon monoxide production while longer wavelengths (640-800 nm) favor hydrogen evolution, with the effect driven by hot-carrier energy rather than heat. This work resolves a longstanding debate about how plasmonic catalysts work and could inform the design of light-driven systems for sustainable fuel and chemical synthesis.
Researchers deployed operando scanning photoelectrochemical microscopy to demonstrate wavelength-dependent selectivity in CO2 reduction on plasmonic Au/p-GaN photocathodes. By carefully controlling photon energy while maintaining constant absorbed power, they isolated the role of hot-carrier energy from competing photothermal effects, showing that interband excitation (460-560 nm) selectively produces CO while intraband excitation (640-800 nm) favors H2 evolution. Density functional theory calculations confirmed that higher-energy interband excitation increases overlap between hot-electron-accessible states and CO-producing intermediates, explaining the experimental selectivity patterns. The team also identified geometric constraints on selectivity, finding that sub-100 nm nanostructures sustain CO2R activity while larger ~300 nm nanodisks suffer transport losses. Together, these findings establish photon energy, carrier transport, and nanostructure geometry as coupled design parameters for plasmonic catalysis and validate photo-SECM as a platform for studying photoelectrocatalytic systems.
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- arXiv physicsCenter
Revealing Wavelength- and Size-Dependent CO2 Reduction Selectivity via Operando Scanning Photo-Electrochemical Microscopy
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