Highly\nEfficient Photocatalytic Activity of g‑C₃N₄/Ag₃PO₄ Hybrid Photocatalysts\nthrough Z‑Scheme Photocatalytic Mechanism under Visible Light

Abstract

Highly\nefficient visible-light-driven g-C₃N₄/Ag₃PO₄ hybrid photocatalysts with different\nweight ratios of g-C₃N₄ were prepared by a facile\nin situ precipitation method and characterized by X-ray diffraction,\nscanning electron microscopy, transmission electron microscopy, Fourier\ntransform infrared spectrometry and UV–vis diffuse reflectance\nspectroscopy. Under visible-light irradiation (>440 nm), g-C₃N₄/Ag₃PO₄ photocatalysts\ndisplayed\nthe higher photocatalytic activity than pure g-C₃N₄ and Ag₃PO₄ for the decolorization of\nmethyl orange (MO). Among the hybrid photocatalysts, g-C₃N₄/Ag₃PO₄ with 25 wt % of g-C₃N₄ exhibited the highest photocatalytic activity\nfor the decolorization of MO. The complete decolorization of MO was\nachieved for only 5 min of visible-light irradiation. X-ray photoelectron\nspectroscopy results revealed that metallic Ag particles on the surface\nof g-C₃N₄/Ag₃PO₄ hybrid\nwere formed during the catalysts preparation. In addition, the quenching\neffects of different scavengers displayed that the reactive h⁺ and O₂^•– play the major\nrole in the MO decolorization. The photocatalytic activity enhancement\nof g-C₃N₄/Ag₃PO₄ hybrid\nphotocatalysts could be ascribed to the efficient separation of electron–hole\npairs through a Z-scheme system composed of Ag₃PO₄, Ag and g-C₃N₄, in which Ag particles act\nas the charge separation center. The evidence of the Z-scheme photocatalytic\nmechanism of the hybrid photocatalysts could be obtained from a photoluminescence\ntechnique.