Accelerated degradation of pollutants via a close interface connection in heterojunction, and special solid-liquid interactions

Abstract

The solid-solid or solid-liquid interfaces are vital for the photocatalytic reaction. Herein, AgI nanoparticles (NPs) attached on the (0 1 1) plane of Ag2WO4 nanorods were synthesized by a facile method at room temperature. The co-crystalization of the two components caused their phase transformation and the existence of a strong interface interaction. Meanwhile, the porous batt-like morphology of AgI NPs provided more contact sites for organic pollutants to induce a strong interaction at the solid-liquid interface. The heterojunction nanocatalyst was found to be highly effective for the degradation and mineralization of various pollutants, including the endocrine-disrupting chemical bisphenol A, the antibiotics sulfamethoxazole and ciprofloxacin, and the azo-dye methyl orange under visible light (λ > 420 nm). Its photocatalytic rate was 91, 52, and 39 times higher than that of bulk AgI, standard TiO2-xNx, and the physical mixture of the two components, respectively. Further studies demonstrated that the strong interactions between the two components and the pollutants promoted the electron transfer from organic pollutants to AgI NPs and then from AgI NPs to Ag2WO4 nanorods, resulting in the rapid oxidation of pollutants and the formation of Ag NPs. The newly formed Ag NPs further accelerated the degradation of pollutants due to a SPR effect and an empty levels feeding role to produce h+ on Ag2WO4, which can oxidize surface-adsorbed H2O into OH. This photocatalytic system provided a platform for understanding solid-solid and solid-liquid interface interaction and a novel design idea for water pollutants removal.