Facile fabrication of a direct Z-scheme MoO3/Ag2CrO4 composite photocatalyst with improved visible light photocatalytic performance

Abstract

A direct Z-scheme type MoO3/Ag2CrO4 composite photocatalyst was successfully fabricated using a facile in situ precipitation method and characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the as-obtained MoO3/Ag2CrO4 composite was evaluated by the photo-degradation of methyl orange (MO) under visible light irradiation (λ > 420 nm). Compared with pure Ag2CrO4 and MoO3, MoO3/Ag2CrO4 composites presented enhanced photocatalytic activities in the degradation of MO. Significantly, the optimal MoO3(4.0 wt%)/Ag2CrO4 sample showed the highest degradation rate of MO, which was approximately 2.5 times higher than that of Ag2CrO4 and 13 times larger than that of MoO3, respectively. Such an enhancement could be mainly ascribed to the efficient separation of photogenerated charge carriers through a Z-scheme system composed of Ag2CrO4 and MoO3. Furthermore, a direct Z-scheme mechanism responsible for the photocatalytic activity enhancement in the MoO3/Ag2CrO4 binary photocatalytic system was proposed based on the results of energy band positions, active species trapping experiments and photoluminescence spectroscopy.