Surface oxygen vacancies prompted the formation of hydrated hydroxyl groups on ZnOx in enhancing interfacial catalytic ozonation

Abstract

Herein, a highly dispersed catalyst (ZnOx-500) was synthesized for heterogeneous catalytic ozonation (HCO), which had a simple ZnO crystal phase but riched in oxygen vacancies (OVs). The O3/ZnOx-500 system exhibited both superior catalytic activity and stability after several cycles, providing a promising strategy for atrazine (ATZ) removal. The strong inhibition of phosphoric acid validated the dominant role of the hydroxyl group (−OH) from water molecule (H2O) dissociation on the zinc site near OVs. Density functional theory calculation further revealed that OVs on (100) and (101) planes could make more zinc sites exposed and facilitate the formation of hydrated −OH, which was easier to approach O3 for its decomposition to generate hydroxyl radical (•OH). This work revealed the intrinsic relationship between OVs and hydrated −OH in an aqueous solution, providing new insight into the solid-liquid interface mechanism of HCO.