A Co-doped Ag₃PO₄ photocatalyst: Efficient degradation of organic pollutants and enhancement mechanism

In this study, an efficient Co-doped Ag₃PO₄ photocatalyst was prepared by the deposition method. Compared with Ag₃PO₄, the degradation efficiency of the optimal sample CAP-2 (the mole ratio of Co/Ag was 0.057 %) for MO (20 mgL⁻¹) increased from 53.4 % to 95.0 % within 20 min, and the degradation efficiency for phenol (20 mgL⁻¹) increased from 57.9 % to 91.8 % within 80 min. Moreover, the CAP-2 sample performed excellent mineralization ability and stable recycling capacity. Free radical capture experiments and electron spin resonance (ESR) measurements indicated that holes (h⁺) and superoxide radicals (⋅O²⁻) were the main active radicals. Doping Co ions broadened the optical absorption, introduced impurity level to promote the separation of carriers, and generated additional ⋅O²⁻ owing to the mutual conversion of Co³⁺ and Co²⁺, thus considerably improving Ag₃PO₄ photocatalytic performance. This work provides a new reference for doping metal ions modified semiconductor photocatalysts to efficiently degrade organic pollutants.