In situ preparation of two-dimensional mortise and tenon structure g-C3N4/MoO3 photocatalyst for the reduction of aqueous Cr(VI)

Abstract

In situ solid-state synthesis was employed to prepare the [Formula: see text] (CM) heterojunctions with a two-dimensional mortise and tenon structure. The prepared products were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy, suggesting that amorphous graphitic carbon was obtained. The photocatalytic performance of the prepared photocatalysts was evaluated in aqueous Cr(VI) reduction reactions under visible-light ([Formula: see text] > 420 nm) irradiation. The results of the experiments showed that the photocatalytic activity of CM is influenced by the composition of heterojunctions. The optimum photocatalytic activity for the photocatalytic reduction of Cr(VI) was found in the compound CM-25, which contains a 25% [Formula: see text] concentration. The Cr(VI) reduction rate on CM-25 was four times that of [Formula: see text] and 14.5 times that of [Formula: see text], the photocatalytic activity of CM-25 only dropped by 7.7% in four cycles. Scavenger investigations and EPR tests indicated that the major photogenerated radicals in the reduction of Cr(VI) were superoxide negative radicals (•[Formula: see text]) and hydroxyl radicals (•[Formula: see text]OH). CM-25 was discovered to be an S-scheme heterojunction that effectively suppressed photogenerated charge carrier recombination and retained photogenerated holes (in the valence band of [Formula: see text]) and electrons (in the conduction band of [Formula: see text]) with higher redox capabilities. CM-25 has potential applications in the photocatalytic reduction of Cr(VI) in wastewater.