Bi/S Co-Doping of CeVO₄ for Enhanced Photocatalytic Hydrogen Evolution: Insights into Multivalent Ce/V States and...

Herein, a simple and environmentally benign synthetic strategy is developed to construct a hydrazine-regulated Bi/S co-doped CeVO₄ trimetallic sulfur-oxide photocatalyst (Bi/S-CeVO₄). The resulting material features abundant oxygen vacancy (Vo) defects and stabilized multivalent Ce³⁺/Ce⁴⁺ and V⁴⁺/V⁵⁺ states, which synergistically enhance photocatalytic hydrogen evolution reaction (PHER) performance under visible light irradiation. Band structure analyses indicate that Bi/S co-doping effectively modulates the electronic structure of CeVO₄, leading to improved photocatalytic performance toward PHER. The coexistence of multivalent Ce³⁺/Ce⁴⁺ and V⁴⁺/V⁵⁺ species provides efficient electron-hopping pathways, facilitating photogenerated charge separation and transfer while prolonging carrier lifetime. In addition, Vo defects served as catalytic sites for water-molecule adsorption and activation, further accelerating surface reaction kinetics. Benefiting from these synergistic effects, the optimized Bi/S-CeVO₄-3, featuring the highest electrochemically active surface area of 0.0015 cm² and Vo concentration of 24.5%, and suitable ratio of Ce⁴⁺/(Ce³⁺+Ce⁴⁺) (41.8%) and V⁴⁺/(V⁴⁺+V⁵⁺) (38.5%), delivers the highest PHER rate of 1514.7 μmol·h^-1, with an apparent quantum efficiency (AQE) x-ray diffraction of 15.28% at 420 nm. Moreover, the catalyst demonstrates excellent stability and durability. This work presents a feasible and effective strategy for electronic structure and defect engineering of CeVO₄-based photocatalysts to achieve efficient solar-driven hydrogen evolution.