Nanostructured NiCo2O4/BiVO4Heterojunctions for Visible-Light Photocatalytic H2O-to-H2O2Synchronized Organic Pollutant Oxidation

Abstract

Photocatalytic H2O2generation using unlimited solar energy for in situ oxidation of organic pollutants in wastewater has been environmentally attractive. Photocatalytic H2O-to-H2O2(aq)reaction by BiVO4, however, suffered from relatively low yields (e.g., 24 μM h-1) under visible-light irradiation, mainly due to its high recombination rate of charge carriers. Herein, nanostructured NiCo2O4/BiVO4Z-scheme heterojunctions were prepared to increase the oxygen reduction reaction for a higher H2O2yield rate (than BiVO4by 16 times approximately). Additionally, highly reactive superoxide (•O2-) and hydroxyl (•OH) radicals from the photocatalytic H2O-to-H2O2process enhanced oxidation of a representative organic pollutant (i.e., methylene blue) under visible-light irradiation. The photocatalytic oxidation rate constant was as high as 2 × 10-7M-1s-1. This visible-light photocatalytic H2O-to-H2O2synchronized oxidation of an organic pollutant by the nanostructured NiCo2O4/BiVO4heterojunctions demonstrates the possibility for a potential energy self-sufficient organic wastewater treatment process.