Hydrazine-driven cation valence regulation and defect engineering in CeVO4 for highly efficient reduction of organic dyes and heavy metal pollutants in the dark
Tetragonal wakefieldite (CeVO 4 )-like CeVOS catalysts with exceptional performance in catalytic reduction of Cr 6+ , MB, and RhB pollutants in the presence of NaBH 4 under dark was prepared via a green and facile method. Hydrazine reduces V 5+ ions to elevate the V 4+ contents, and sulfur-doped is employed to balance lattice deviations from electrical neutrality induced by high V 4+ concentrations, enhancing overall stability. Hydrazine modulation regulates the V 4+ /(V 4+ +V 5+ ) ratio, influencing sulfur doping, defect structure, and electron transfer efficiency. The CeVOS catalyst with an optimized V 4+ /(V 4+ +V 5+ ) ratio of 0.46 with abundant oxygen vacancies and exhibited exceptional catalytic performance. The 100 mL 50 ppm Cr 6+ , MB, and RhB solution were completely reduced in 10 min and durable stability, after six runs, it still achieved a 98.8% reduction of Cr 6+ within 10 min. Response surface methodology (RSM) elucidated variable interactions and their influence on catalytic reduction performance. The model’s robustness is underscored by a predicted R 2 of 0.9345. Optimal conditions for pollutant treatment in practical applications are 15 mg of catalyst, 25 mg of sacrificial agent, and a pH value of 6.8. Therefore, the green synthesis of efficient CeVOS catalysts bears excellent promise for industrial wastewater treatment .
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