A novel ZnCo2O4/BiOBr p-n/Z-scheme heterojunction photocatalyst for enhancing photocatalytic activity

Abstract

Abstract In this paper, a novel p-n/Z-scheme heterojunction photocatalyst, ZnCo2O4/BiOBr (ZCo/BB) was prepared by a simple and safe hydrothermal-calcination-solvent thermal method. The prepared composite photocatalyst displayed superior photocatalytic behavior when the mass ratio of ZnCo2O4 was 25% ( the catalyst of 25 wt% ZnCo2O4 composite BioBr was named 25% ZCo/BB). The structure characterization and electrochemical performance showed that the 25% ZCo/BB has a larger specific surface area and a faster electron transfer rate. After being exposed to visible light for 30 minutes, methylene blue (MB) degraded to 92% and the reaction rate constants were 8.2 and 3.7 times greater than those of single ZnCo2O4 and BiOBr, respectively. The modified photocatalysts (25% ZCo/BB) also exhibited excellent photocatalytic stability throughout the circulation with over 80% MB degradation remaining after 4 cycles. The outstanding photocatalytic activity was associated with the p-n/Z-scheme heterojunction construction, which promoted charge separation and inhibited carrier recombination. In addition, ·OH and h+ were the major active species in photocatalysis, and ·O2− was a secondary active species. An efficient heterojunction photocatalyst for the degradation of organic wastewater is presented in this work.