Oxygen vacancy-assisted 3DOM TiO₂-Zn_xCd_1-xS heterojunctions for enhanced photocatalytic hydrogen production

Photocatalytic hydrogen production is a promising strategy for alleviating the energy and environment crises. 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 vacancy-assisted three-dimensionally ordered macroporous (3DOM) TiO₂-Zn_xCd_1-xS composite photocatalysts are designed for enhanced hydrogen production. In this heterojunction structure, the interfaces between TiO₂ and Zn_xCd_1-xS 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. This enables the composite with the Zn/Cd molar ratio of 1 : 1 to achieve 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.