An innovative p-n heterojunction Bi2S3/ZnCo2O4 composite was first fabricated via a two-step co-precipitation and hydrothermal method. By controlling the weight amount of Na2S and Bi(NO3)3 precursor, different heterogeneous xBi2S3/ZnCo2O4 were synthesized (x = 0, 2, 6, 12, and 20). The p-n heterojunction Bi2S3/ZnCo2O4 was characterized by structural, optical, and photochemical properties and the photocatalyst decoloration of indigo carmine. Mott-Schottky plots proved a heterojunction formed between n-Bi2S3 and p-ZnCo2O4. Furthermore, the investigation of the photocurrent response indicated that the Bi2S3/ZnCo2O4 composite displayed an enhanced response, which was respectively 4.6 and 7.3 times (4.76 μA cm-2) greater than that of the pure Bi2S3 (1.02 μA cm-2) and ZnCo2O4 (0.65 μA cm-2). Especially the optimized p-n Bi2S3/ZnCo2O4 heterojunction with 12 wt% Bi2S3 showed the highest photocatalyst efficacy of 92.1% at 40 mg L-1 solutions, a loading of 1.0 g L-1, and a pH of 6 within 90 min of visible light illumination. These studies prove that p-n Bi2S3/ZnCo2O4 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.
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