Reduced graphene oxide supported on Gd2MoO6-ZnO nanorod photocatalysts used for the effective reduction of hexavalent chromium

A reduced graphene oxide (rGO)-Gd2MoO6-ZnO nanocomposite was synthesized using a hydrothermal method, in which rod-shaped ZnO and plate-like Gd2MoO6 were decorated on rGO sheets. The as-prepared photocatalyst was characterized using X-ray diffraction, optical studies, photoluminescence measurements, surface morphology, chemical states, and photocurrent density studies. A stable photocatalytic performance was achieved using the synergetic Gd2MoO6-rGO-ZnO composite catalyst during the reduction of Cr(VI) to benign Cr(III) compared with the performance achieved using bare and binary composite catalysts. The effects of various parameters, such as different weight ratios and solution pH, were investigated. An optimized pH of 4 was used for the effective reduction of Cr(VI) to Cr(III). The maximum photocatalytic reduction performance (94.5%) was achieved within 160 min. Photocurrent density and PL emission measurements confirmed the fast charge transfer and effective charge separation over Gd2MoO6-rGO-ZnO, which improved the Cr(VI) reduction. A photocatalytic Cr(VI) reduction mechanism for Gd2MoO6-rGO-ZnO was proposed.

Automated summary

A rGO-Gd2MoO6-ZnO nanocomposite was synthesized through hydrothermal method, showing stable photocatalytic performance in reducing Cr(VI) to Cr(III). Optimized pH and fast charge transfer were found to enhance the photocatalytic reduction efficiency to 94.5% within 160 min.