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

Herein, a simple and environmentally benign synthetic strategy is developed to construct a hydrazine-regulated Bi/S co-doped CeVO 4 trimetallic sulfur-oxide photocatalyst (Bi/S-CeVO 4 ). The resulting material features abundant oxygen vacancy (Vo) defects and stabilized multivalent Ce 3+ /Ce 4+ and V 4+ /V 5+ 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 CeVO 4 , leading to improved photocatalytic performance toward PHER. The coexistence of multivalent Ce 3+ /Ce 4+ and V 4+ /V 5+ 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-CeVO 4 -3, featuring the highest electrochemically active surface area of 0.0015 cm 2 and Vo concentration of 24.5%, and suitable ratio of Ce 4+ /(Ce 3+ +Ce 4+ ) (41.8%) and V 4+ /(V 4+ +V 5+ ) (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 CeVO 4 -based photocatalysts to achieve efficient solar-driven hydrogen evolution. Graphical Inspired by battery-material redox chemistry, hydrazine-regulated Bi/S co-doping constructs a defect-rich CeVO 4 sulfur-oxide with stabilized multivalent states, enabling a photocatalytic hydrogen evolution reaction rate of 1514.7 μmol·h –1 and an apparent quantum efficiency of 15.28% at 420 nm.