Highly Efficient Photocatalytic Activity of g-C3N4/Ag3PO4 Hybrid Photocatalysts through Z-Scheme Photocatalytic Mechanism under Visible Light

Abstract

Highly efficient visible-light-driven g-C 3 N 4 /Ag 3 PO 4 hybrid photocatalysts with different weight ratios of g-C 3 N 4 were prepared by a facile in situ precipitation method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry and UV–vis diffuse reflectance spectroscopy. Under visible-light irradiation (>440 nm), g-C 3 N 4 /Ag 3 PO 4 photocatalysts displayed the higher photocatalytic activity than pure g-C 3 N 4 and Ag 3 PO 4 for the decolorization of methyl orange (MO). Among the hybrid photocatalysts, g-C 3 N 4 /Ag 3 PO 4 with 25 wt % of g-C 3 N 4 exhibited the highest photocatalytic activity for the decolorization of MO. The complete decolorization of MO was achieved for only 5 min of visible-light irradiation. X-ray photoelectron spectroscopy results revealed that metallic Ag particles on the surface of g-C 3 N 4 /Ag 3 PO 4 hybrid were formed during the catalysts preparation. In addition, the quenching effects of different scavengers displayed that the reactive h + and O 2 •– play the major role in the MO decolorization. The photocatalytic activity enhancement of g-C 3 N 4 /Ag 3 PO 4 hybrid photocatalysts could be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag 3 PO 4, Ag and g-C 3 N 4, in which Ag particles act as the charge separation center. The evidence of the Z-scheme photocatalytic mechanism of the hybrid photocatalysts could be obtained from a photoluminescence technique.