Band gap-controllable N, P co-doped carbon@Zn Cd1−In2S4 for photocatalytic reduction of chromium(VI) and degradation of tetracycline hydrochloride

Construction of carbon-based heterostructural photocatalyst materials with high electron transfer rates is a practical and effective strategy for the mineralization of organic pollutants and removal of toxic metal ions under visible-light irradiation. This study developed a facile hydrothermal route to prepare a series of heterojunction photocatalysts, wherein ZnxCd1-xIn2S4 nanosheets were immobilized on nitrogen and phosphorus co-doped hollow carbon spheres (N, P-C) to form N, P-C@ZnxCd1-xIn2S4 nanocomposites. Comprehensive characterization of the nanocomposites revealed that the tuning of the Zn/Cd molar ratio could effectively modulate the ZnxCd1−xIn2S4 energy band structure. Moreover, Zn0.5Cd0.5In2S4 had the most negative conduction band position and loads on non-metal-doped carbon, with superior carrier transport properties and separation efficiency. N, P-C@Zn0.5Cd0.5In2S4 (N, P-C@ZCIS2) exhibited the best photocatalytic activity for tetracycline hydrochloride degradation and Cr(VI) reduction, with rate constants of 0.04822 mg−1 min−1 and 0.14303 min−1, respectively. Notably, the photocatalysts exhibited good activity and stability even after cycle experiment. This study provides new insights into the design of carbon-based heterojunction photocatalysts for the removal of harmful chemicals.