Rationally constructing of a novel composite photocatalyst with multi charge transfer channels for highly efficient sulfamethoxazole elimination: Mechanism, degradation pathway and DFT calculation

Rational design of highly efficient multi-heterojunction photocatalyst with separated charge transfer channels still remains a challenge. Herein, a novel La2Ti2O7/g-C3N4/AgI photocatalyst is constructed via a facile electrostatic self-assembly plus selective deposition–precipitation method. The results demonstrate that the spatially isolated La2Ti2O7 and AgI are both decorated tightly on g-C3N4 nanosheets and form separated heterojunctions, which provide much more separated charge transfer channels and surface reaction sites. Therefore, the samples exhibit remarkably boosted photodegradation performance for sulfamethoxazole (SMZ). DFT results indicate that the atoms with the most positive and negative value of condensed dual descriptors (CDD) are the mostly vulnerable to reactive species. Aromatic amine oxidation, the cleavage of sulfonamide bond and hydroxylation of aromatic rings are mainly SMZ degradation pathways. This study provides a new insight for the guideline of rational design/development of new multicomponent photocatalysts for potential application on treatment of emerging pollutants in waters.