Noble-metal-free plasmonic MoO3−-based S-scheme heterojunction for photocatalytic dehydrogenation of benzyl alcohol to storable H2 fuel and benzaldehyde

Simultaneous generation of H2 fuel and value-added chemicals has attracted increasing attention since the photogenerated electrons and holes can be both employed to convert solar light into chemical energy. Herein, for realizing UV-visible-NIR light driven dehydrogenation of benzyl alcohol (BA) into benzaldehydes (BAD) and H2, a novel localized surface plasmon resonance (LSPR) enhanced S-scheme heterojunction was designed by combining noble-metal-free plasmon MoO3–x as oxidation semiconductor and Zn0.1Cd0.9S as reduction semiconductor. The photoredox system of Zn0.1Cd0.9S/MoO3–x displayed an unconventional reaction model, in which the BA served as both electron donor and acceptor. The S-scheme charge transfer mechanism induced by the formed internal electric field enhanced the redox ability of charge carriers thermodynamically and boosted charge separation kinetically. Moreover, due to the LSPR effect of MoO3−x nanosheets, Zn0.1Cd0.9S/MoO3−x photocatalysts exhibited strong absorption in the region of full solar spectrum. Therefore, the Zn0.1Cd0.9S/MoO3−x composite generated H2 and BAD simultaneously via selective oxidation of BA with high production (34.38 and 33.83 mmol·g−1 for H2 and BAD, respectively) upon full solar illumination. Even under NIR light irradiation, the H2 production rate could up to 94.5 mmol·g−1·h−1. In addition, the Zn0.1Cd0.9S/MoO3–x composite displayed effective photocatalytic H2 evolution rate up to 149.2 mmol·g−1·h−1 from water, which was approximate 6 times that of pure Zn0.1Cd0.9S. This work provides a reference for rational design of plasmonic S-scheme heterojunction photocatalysts for coproduction of high-value chemicals and solar fuel production.