Insights into the mechanism of enhanced photocatalytic dye degradation and antibacterial activity over ternary ZnO/ZnSe/MoSe2 photocatalysts under visible light irradiation

Abstract

Breakthroughs of photocatalytic techniques used for environmental remediation still heavily rely on the development of promising photocatalysts with efficient charge migration and broad-spectrum optical absorption. Herein, we report ternary ZnO/ZnSe/MoSe2 heterojunctions as candidate photocatalysts for the degradation of methyl orange (MO) and the sterilization of Escherichia coli (E. coli). The mechanism behind the ZnO/ZnSe/MoSe2 based photocatalysis is also thoroughly explored. In comparison with ZnO and ZnO/ZnSe, the as-prepared ZnO/ZnSe/MoSe2 has superior utilization efficiency of visible light and higher separation efficiency of photo-induced electron-hole pairs. In addition, compared to ZnO and ZnO/ZnSe, ZnO/ZnSe/MoSe2 exhibits remarkably enhanced photocatalytic activity with the MO degradation efficiency of 91.5% after 180 min and the inactivation of approximately 4.97 log E. coli cells after 120 min. The ESR spin-trapping investigation indicates that more radicals (O2– and OH) are produced by ZnO/ZnSe/MoSe2 under visible light irradiation. The mechanistic study further reveals that a gradual charge transfer in ZnO/ZnSe/MoSe2 leads to the improved separation of electron-hole pairs.