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DOE OSTI · 3380286

Modulating Mid-Gap Electronic States Through Site-Selective Modification in B-Pbx/B'-CuyV2O5/CdS Heterostructures for Photocatalytic Hydrogen Evolution

Garcia-Pedraza, Karoline [University at Buffalo, State University of New York]·Ayala, Jaime [Texas A&M University]·Giem, Alice [Texas A&M University]·Wijethunga, Udani [University at Buffalo, State University of New York]·Gouda, Ashrumochan [University at Buffalo, State University of New York]·Pakhira, Anindya [Texas A&M University]·Minassian, Megan [Texas A&M University]·Reilly, Nicholas [University at Buffalo, State University of New York]·Agbeworvi, George [Texas A&M University]·Ponis, John [Texas A&M University]·Smeaton, Michelle [National Laboratory of the Rockies, Golden, CO (United States)]·Watson, David [University at Buffalo, State University of New York]·Banerjee, Sarbajit [ETH Zurich; Paul Scherrer Institute]
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Abstract

We interfaced ..beta..-Pbx/..beta..'-CuyV2O5 compounds, with varying stoichiometries of precisely positioned Pb-ions (x) and Cu-ions (y) in interstitial sites along a tunnel-structured ?-V2O5 framework, with cysteine-capped CdS (cysCdS) quantum dots (QDs) to yield heterostructured photocatalysts. ..beta..-Pbx/..beta..'-CuyV2O5 compounds exhibit midgap electronic states with orbital contributions from both Cu 3d and stereochemically active Pb 6s states that show distinctive light-initiated reactivity with photoexcited QDs. ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures were prepared by linker-assisted assembly (LAA). Scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy revealed that cysCdS QDs were deposited onto surfaces of ..beta..-Pbx/..beta..'-CuyV2O5 via LAA. HAXPES revealed that the site-selective positioning of Pb-ions and Cu-ions promoted close energetic alignment of the midgap states of ..beta..-Pbx/..beta..'-CuyV2O5 compounds with the valence-band maximum of cysCdS QDs. Transient absorption spectroscopy revealed that photogenerated holes were transferred from CdS QDs to midgap states of ..beta..-Pbx/..beta..'-CuyV2O5 compounds on time scales <50 ps. Finally, photoelectrochemical and photochemical experiments revealed that ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures promoted the photocatalytic reduction of H+ to H2. In photoelectrochemical experiments, under oxidative conditions, for all ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures, H2 was evolved at a Pt counter electrode while a sacrificial donor was oxidized at the heterostructure-functionalized working electrode. In contrast, under reductive conditions, for ..beta..-Pb0.152V2O5/CdS and ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures, H2 was evolved at the working electrode. In photochemical experiments, dispersed ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures promoted the reduction of H+ to H2 under white-light illumination; ..beta..'-Cu0.55V2O5/CdS and ..beta..-Pbx/..beta..'-CuyV2O5/CdS heterostructures, for which midgap states have Cu 3d orbital character, generated 2-fold more H2 than ..beta..-Pb0.152V2O5/CdS heterostructures. Cu-ion insertion thus appends additional acceptor surface states that improve ligand-mediated hole transfer from photoexcited QDs, but such states are intrinsically limited in mediating hole transport to the substrate as a result of the low mobility of holes in narrow Cu 3d-states. Our results reveal that the density and orbital character of midgap states of ..beta..-Pbx/..beta..'-CuyV2O5 compounds, tunable through recently developed site-selective ion insertion strategies, determine efficiencies of charge-transfer and charge-transport mechanisms that underpin photocatalysis.

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36 MATERIALS SCIENCE37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYco-insertionexcited-state charge transfermid-gap statesphotocatalysisphotochemistryquantum dotsvanadium oxides

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Garcia-Pedraza, Karoline [University at Buffalo, State University of New York], Ayala, Jaime [Texas A&M University], Giem, Alice [Texas A&M University], Wijethunga, Udani [University at Buffalo, State University of New York], Gouda, Ashrumochan [University at Buffalo, State University of New York], Pakhira, Anindya [Texas A&M University], Minassian, Megan [Texas A&M University], Reilly, Nicholas [University at Buffalo, State University of New York], Agbeworvi, George [Texas A&M University], Ponis, John [Texas A&M University], Smeaton, Michelle [National Laboratory of the Rockies, Golden, CO (United States)], Watson, David [University at Buffalo, State University of New York], Banerjee, Sarbajit [ETH Zurich; Paul Scherrer Institute]. 2026-06-18. Modulating Mid-Gap Electronic States Through Site-Selective Modification in B-Pbx/B'-CuyV2O5/CdS Heterostructures for Photocatalytic Hydrogen Evolution. https://doi.org/10.1021/acsami.6c08211

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36 MATERIALS SCIENCE↗