A novel n-p heterojunction BiS/ZnCoO photocatalyst for boosting visible-light-driven photocatalytic performance toward indigo carmine.

An innovative p-n heterojunction BiS/ZnCoO composite was first fabricated a two-step co-precipitation and hydrothermal method. By controlling the weight amount of NaS and Bi(NO) precursor, different heterogeneous BiS/ZnCoO were synthesized ( = 0, 2, 6, 12, and 20). The p-n heterojunction BiS/ZnCoO was characterized by structural, optical, and photochemical properties and the photocatalyst decoloration of indigo carmine. Mott-Schottky plots proved a heterojunction formed between n-BiS and p-ZnCoO. Furthermore, the investigation of the photocurrent response indicated that the BiS/ZnCoO composite displayed an enhanced response, which was respectively 4.6 and 7.3 times (4.76 μA cm) greater than that of the pure BiS (1.02 μA cm) and ZnCoO (0.65 μA cm). Especially the optimized p-n BiS/ZnCoO heterojunction with 12 wt% BiS showed the highest photocatalyst efficacy of 92.1% at 40 mg L solutions, a loading of 1.0 g L, and a pH of 6 within 90 min of visible light illumination. These studies prove that p-n BiS/ZnCoO heterojunction photocatalysts can greatly boost their photocatalytic performance because the inner electric field enhances the process of separating photogenerated electron-hole pairs. Furthermore, this composite catalyst showed good stability and recyclability for environmental remediation.