Effective visible light-driven ternary composite of ZnO nanorod decorated Bi2MoO6 in rGO for reduction of hexavalent chromium

Abstract

The construction of ternary composite materials is an excellent approach for achieving effective charge separation and enhanced photocatalytic performance. In this study, a ternary Bi2MoO6-rGO-ZnO nanocomposite photocatalyst was prepared by a simple hydrothermal method and characterized by various surface analytical optical techniques. Field emission scanning electron microscopy and high-resolution transmission electron microscopy analyses revealed that rice-like structured Bi2MoO6 decorated on ZnO nanorods were dispersed in reduced graphene oxide (rGO) sheets. The photocatalytic efficiency of this nanocomposite was studied by the reduction of hexavalent Cr(VI) under visible-light illumination. The ternary catalyst had a 95.4% reduction of Cr(VI) in 70 min, which is greater than that of Bi2MoO6, and ZnO-Bi2MoO6 owing to the maximum charge separation and excellent electron transport between ZnO and Bi2MoO6 catalyst on the rGO. The prepared ternary catalyst exhibited low photoluminescence and maximum photocurrent density, indicating the suppression of photon-induced electron–hole recombination and high charge separation. The ternary Bi2MoO6-rGO-ZnO catalyst was stable for up to three consecutive cycles of Cr(VI) reduction. A feasible photocatalytic reduction mechanism using the prepared ternary composite material was proposed.