Synergistic removal of dimethoate through adsorption and photocatalytic oxidation in the presence of FeTiO3@Ag/Ag2O heterojunction

Combining adsorption and photocatalysis as a synergistic technique has become a research trend since adsorption is a prerequisite for photocatalytic surface reactions. In this study, a Z-scheme heterojunction FeTiO3@Ag/Ag2O with local surface plasmon resonance (LSPR) effect was fabricated for the removal of dimethoate from water. Under visible light irradiation, dimethoate could be completely removed within 75 min in the presence of 0.3 g/L FeTiO3@Ag/Ag2O (with Ag2O percentage of 10 wt%). High removal efficiency of dimethoate was mainly attributed to the synergistic effect between the large specific surface area of the catalyst (160.695 m2/g), the formation of heterojunction of FeTiO3 and Ag2O, and the LSPR effect of metal Ag, which reinforced the absorption of visible light and promoted the separation and transfer of the carriers. Radicals of O2− and OH were the main reactive groups triggered the photocatalytic degradation process of dimethoate. Density Functional Theory (DFT) calculations indicate that PS and P–S bonds in the dimethoate molecule were more susceptible to be attacked by reactive groups. The degradation pathways mainly include oxidation of PS bond and cleavage of P–S bond, and the toxicity of most intermediates was reduced when compared with the parent compound. This study exploited the role of adsorption and photocatalysis in the field of pollutant removal, and provides ideas for the preparation of bifunctional photocatalysts.