Year: 2026
Type: preprint
Abstract: Metal-semiconductor junctions in optoelectronic devices are commonly engineered to promote charge separation. In Pt/TiO2 Schottky junctions, Pt is typically regarded as a catalytic electron sink rather than a visible-light-active component. Here, we demonstrate that Pt nanoislands on TiO2 can generate photochemically active carriers under visible light excitation. Using quantitative scanning photoelectrochemical microscopy, we measure the wavelength-resolved external quantum efficiency (EQE) of Au and Pt nanoisland arrays on TiO2, and correlate their reactivity with their morphology and extinction spectra. Discrete 10 nm Pt nanoislands exhibit robust broadband visible light photoactivity - exceeding the photoactivity of similar-sized Au nanoislands under blue-green excitation - whereas Pt's photoactivity is strongly suppressed when the nanoislands are connected. Surprisingly, Pt exhibits an EQE-per-atom approx. 20 times higher than Au at 455 nm and approx. 2 times higher at 595 nm (at Au's optimum). We show an approximately wavelength-independent Pt internal quantum efficiency of approx. 1 percent across the visible spectral region. These findings reposition catalytic metals with strongly damped optical response in the visible as light-responsive components in metal-semiconductor hybrids, challenging the prevailing perception that they function solely as passive co-catalysts in photocatalytic systems.
Source: arXiv (Cornell University)
Field: Energy
Domain: Physical Sciences
Open Access status: green
Funders: Solar Technologies go Hybrid, Dipartimenti di Eccellenza, European Commission, Deutsche Forschungsgemeinschaft, Ministerstvo Školství, Mládeže a Tělovýchovy, Grantová Agentura České Republiky, Ministero dell’Istruzione, dell’Università e della Ricerca, Central European Institute of Technology, HORIZON EUROPE Framework Programme, Engineering and Physical Sciences Research Council, European Regional Development Fund, European Social Fund
Awards: EXC 2089: econversion, G1153767801, G1234657840, G1289397041, G1303340219, G1417226337, G1492781007, G1711002585, G1763122136, G1935710221, G2006013265, G2180221829, G258225891, G2677629327, G2678520069, G2778226874, G291036901, G3076994783, G3331557281, G3735356012, G3771185154, G3810236772, New perspectives in photocatalysis and near-surface chemistry: catalysis meets plasmonics, G4273056302, G4283425136, G4396925471, G4403415030, G4472258033, G5162580495, G5295502948, G534424066, G535059049, G6006474179, G6253592498, G6402224719, G6666489062, G768043058, G8140083606, G9000847340
OpenAlex ID: W7167585992
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