Facile fabrication of a direct Z-scheme Ag2CrO4/g-C3N4 photocatalyst with enhanced visible light photocatalytic activity

Graphite-like carbon nitride (g-C3N4) and silver-based compounds have attracted considerable attentions due to their excellent optical characteristic and photocatalytic performance. In this work, Z-scheme silver chromate-g-C3N4 nanosheets photocatalysts were prepared by binding growth of Ag2CrO4 nanoparticles on the surface of g-C3N4 nanosheets (g-C3N4-N) via a facile precipitation method. The morphologies, structure, specific surface area and optical property of the prepared photocatalysts were characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis DRS) and photoluminescence (PL) spectra. The photocatalytic performances of the prepared Ag2CrO4/g-C3N4-N were evaluated by photodegradation of methyl orange (MO) and rhodamine B (RhB) under visible light irradiation (lambda >400nm). The experiment results indicated that Ag2CrO4/g-C3N4-N composites presented enhanced photocatalytic activity and stability in the degradation of the dye contaminants in aqueous solution. The optimal composites with the mass ratio of Ag2CrO4 to g-C3N4-N as 50% (CNA-50) showed the highest photocatalytic activity for MO degradation, which is 5.9 and 10.8 times than those of pure Ag2CrO4 and pure g-C3N4-N, respectively. The formation of Ag2CrO4/g-C3N4-N Z-scheme heterojunction contributed to the improved photodegradation efficiency, which can not only promote the separation and transportation efficiencies of the photogenerated electron-hole pairs, but also present strong redox ability. And meanwhile the excellent transportation efficiency of the photogenerated electrons from Ag2CrO4 to g-C3N4-N greatly hindered the photocorrosion of Ag2CrO4 nanoparticles. This work provides a new understanding into the mechanism of the g-C3N4-N based composite and gives a new insight into the design and fabrication of Z-scheme photocatalysts. (C) 2016 Elsevier B.V. All rights reserved.