Regulating Surface Reaction Kinetics for Promoting the Activity and Selectivity of Photocatalytic Benzyl Alcohol Oxidation

Abstract

Photocatalysis offers a sustainable route to simultaneously produce hydrogen (H2) and value-added chemicals, but it is often constrained by unsatisfactory activity and selectivity arising from sluggish charge migration kinetics and mismatched surface reaction kinetics. Herein, we report a Ni-modified S-scheme heterostructure formed with W18O49 hollow spheres (WOHS) and ZnIn2S4 (ZIS) nanosheets for efficient H2 evolution coupled with highly selective benzyl alcohol (BA) oxidation. In this composite photocatalyst, a strong internal electric field established between WOHS and ZIS drove directional charge separation, effectively isolating the oxidative and reductive reaction sites to promote the activity and selectivity of surface redox reactions. Moreover, Ni nanoparticles deposited on the ZIS surface acted as efficient electron sinks, rapidly consuming photogenerated electrons to promote H2 production. Critically, this rapid consumption of photogenerated electrons also suppressed the reduction of benzaldehyde (BAD) to form carbon-centered radicals, thereby inhibiting their homocoupling to generate hydrobenzoin (HB). This allows the optimized composite photocatalyst to exhibit an exceptional H2 evolution rate of 11.40 mmol g–1 h–1, with nearly 100% selectivity for BA-to-BAD conversion.