Ball-milling preparation of ZnFeO/AgI nanocomposite with enhanced photocatalytic activity.

Semiconductor photocatalytic technology is increasingly being utilized in wastewater treatment due to its high efficiency, low energy consumption and environmental friendliness. However, single photocatalysts often exhibit low catalytic performance. In this study, a ZnFeO/AgI composite photocatalyst was initially prepared using a high-energy ball-milling method. For the first time, it was applied to the photocatalytic dehydrogenation of diethyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (1,4-DHP), as well as photocatalytic degradation of harmful substances such as amaranth (AM), methyl orange (MO) and indole present in wastewater. The composite photocatalyst exhibited superior catalytic performance compared to ZnFeO and AgI under visible light irradiation ( ≥ 400 nm). With optimized composition, the pseudo-first-order rate constants of ZnFeO/AgI-50% were approximately 6, 20, 64 and 38 times higher than that of AgI for the photooxidation of 1,4-DHP, AM, MO and indole, respectively. The enhanced catalytic activity of the composite was attributed to the formation of heterojunction between ZnFeO and AgI, which facilitated the separation and transfer of photogenerated charge carriers. Mechanism studies revealed that photogenerated holes (h) and superoxide radical anions (˙O ) played pivotal roles in the photocatalytic reaction process.