Heterojunction Cu2O/RGO/BiVO4 ternary nanocomposites with enhanced photocatalytic activities towards degradation of rhodamine B and tetracycline hydrochloride

Abstract

Compared to the traditional type II heterojunction photocatalyst (Cu₂O/BiVO₄), bulk BiVO₄ was modified in this study by reduced graphene oxide (RGO) with a Schottky structure to optimize the coupling interface of BiVO₄. Cu₂O nanoparticles were then grown in situ on the RGO/BiVO₄ surface to yield a heterojunction structure with an internal electric field, allowing movement of photogenerated electrons and holes in opposite directions to participate in redox reactions. The as-obtained optimized Cu₂O/RGO/BiVO₄ material exhibited excellent photocatalytic degradation performance towards organic pollutants. The reaction rate constant of rhodamine B (RhB) was estimated as 0.0324 min⁻¹, which was almost 5.94, 5.15 and 1.94-fold higher than those of bare BiVO₄, 4%RGO/BiVO₄ and 5%Cu₂O/BiVO₄, respectively. Moreover, the optimized material displayed good activity in the degradation of the colorless organic contaminant tetracycline hydrochloride (TC). The reaction rate constant was estimated as 0.0219 min⁻¹, which was almost 1.6-, 1.4- and 1.63-fold higher than those of bare BiVO₄, 4%RGO/BiVO₄ and 5%Cu₂O/BiVO₄, respectively. The hole and superoxide radical worked as active species for degradation of organic matter. Such a significant increase in degradation efficiencies was attributed not only to the formation of a heterojunction structure but also to rapid electron transfer between interfaces.