Oxygen Vacancies Assisted 3DOM TiO2-ZnxCd1-xS Heterojunctions for Enhanced Photocatalytic Hydrogen Production

Abstract

Photocatalytic hydrogen production is a promising strategy for alleviating the energy and environment crisis. However, its practical application is still severely limited by insufficient visible-light utilization, the rapid recombination of photogenerated charge carriers and slow surface reaction efficiency. To address these issues, a series of oxygen vacancies assisted threedimensionally ordered macroporous (3DOM) TiO 2 -Zn x Cd 1-x S composite photocatalysts are designed for enhanced hydrogen production. In this heterojunction structure, the interfaces between TiO 2 and Zn x Cd 1-x S are largely decreased via the in-situ formation process to promote the transfer of photogenerated charge carriers. In particular, the extra-generated oxygen vacancies regulate the band structure of the composite photocatalyst to improve the spatial separation of the photogenerated charge carriers. These make the composite with the Zn/Cd molar ratio of 1:1 achieves a remarkable hydrogen production rate of 20.33 mmol•g⁻¹•h⁻¹ and an apparent quantum efficiency (AQY) of 84.5 % at 365 nm. By harnessing the synergistic effects of heterojunction and oxygen vacancies, this work provides a novel and effective strategy for designing high-performance photocatalysts for photocatalytic hydrogen production.