Interfacial optimization of Z-scheme Ag₃PO₄/MoS₂ nanoflower sphere heterojunction toward synergistic enhancement of visible-light-driven photocatalytic oxygen evolution and degradation of organic pollutant

Samples of flower-like MoS₂ nanosphere-modified Ag₃PO₄ (Ag₃PO₄/MoS₂) were prepared by a facile and reliable method. The morphology and crystal structure of the Ag₃PO₄/MoS₂ composites were investigated by high-resolution transmission electron microscopy, X-ray diffraction, specific surface areas, and X-ray photoelectron spectroscopy. Analysis results indicated that Ag₃PO₄ particles were distributed conformably on the surface of flower-like MoS₂ spheres, and both formed an enhanced heterojunction structure. Fluorescence spectra, surface photocurrent spectra, and electrochemical impedance spectroscopic results showed that an appropriate amount of MoS₂ modification (6 mg) could effectively improve the generation, separation, and migration efficiency of the photogenerated electron/hole pairs (e⁻/h⁺). The photocatalytic activity of the samples was evaluated by photocatalytic O₂ production and photodegradation of the organic molecules under visible-light irradiation. With the increase in the amount of MoS₂, the photocatalytic activity of the Ag₃PO₄/MoS₂ samples increased first and then decreased. The photocatalytic rate reached the fastest when the mass of MoS₂ was 6 mg, which was 7.66- and 9.28-fold of that of pure Ag₃PO₄ for photocatalytic O₂ production and photodegradation of organic molecules, respectively. Sacrificial reagent experiments and electron spin resonance spectra showed that superoxide radicals (•O₂⁻) and holes (h⁺) played a major role in the photocatalytic reaction process. The enhanced photocatalytic performance could be ascribed to the interfacial optimization and formation of Z-scheme heterojunction.