Rational regulation of vacancy species to manage migration paths of carriers in MoS2/TiO2 heterojunctions for efficient photocatalytic H2 generation

Photocatalytic water splitting to produce hydrogen (H₂), as one means to solve environmental pollution and energy shortage, is limited by the serious recombination of photogenerated electrons and holes, resulting in low solar energy conversion efficiency. Thus, steering the behaviors of charge carriers by rationally designing their transport pathway is essential, which can effectively suppress the recombination of electrons and holes. Herein, we designed a MoS₂/TiO₂ heterojunction with different vacancy species to manage the migration paths of photogenerated charge carriers. As demonstrated by experimental characterizations and density functional theory (DFT) calculations, oxygen and sulfur vacancies can induce defect energy levels in heterostructures, which can capture photogenerated holes and electrons, respectively, resulting in substantially promoted charge separation efficiency and longer lifetime of electrons. As expected, the optimized photocatalyst shows a stable H₂ production rate of 1.41 mmol g^?1 h^?1, which is significantly better than that of the bare MoS₂/TiO₂ heterojunction. This finding informs the significance in rational design of the nanostructures for promoting the photocatalytic performance.