Hierarchical microspheres of a mixed metal oxide heterojunction with CuO and Ag/AgCl for enhanced photocatalytic oxidation of organic pollutants and hydrogen production

Abstract

A multicomponent photocatalyst, consisting of ZnTi-oxide oxalate and SiO_x, has been synthesized and interfaced with CuO and Ag/AgCl to enhance bifunctional photocatalytic performance towards hydrogen generation and pollutant degradation. The Ag/AgCl/CuO/MMO (AC–MMO) heterojunction exhibits a hierarchical microsphere morphology with a high specific surface area of 126 m² g⁻¹ and facilitates improved light absorption and charge separation. AC–MMO achieves an impressive hydrogen evolution rate of 283 μmol h⁻¹ g⁻¹, corresponding to a solar-to-hydrogen efficiency of 1.1% under UV-visible light exposure in the presence of a hole scavenger. The heterojunction also exhibits enhanced photocatalytic degradation, demonstrating 90% methyl orange degradation, which is 7.5-fold higher than unmodified MMO under Xe lamp irradiation. At an optimal pH of 8.3, AC–MMO achieves 97% degradation of 4-nitrophenol under broad-spectrum light and 83% degradation under visible light within 60 minutes. These findings highlight the exceptional potential of 0.2AC–MMO as an advanced photocatalyst for water purification and hydrogen production.