A novel n–p heterojunction Bi(2)S(3)/ZnCo(2)O(4) photocatalyst for boosting visible-light-driven photocatalytic performance toward indigo carmine

An innovative p–n heterojunction Bi(2)S(3)/ZnCo(2)O(4) composite was first fabricated via a two-step co-precipitation and hydrothermal method. By controlling the weight amount of Na(2)S and Bi(NO(3))(3) precursor, different heterogeneous xBi(2)S(3)/ZnCo(2)O(4) were synthesized (x = 0, 2, 6, 12, and 20). The p–n heterojunction Bi(2)S(3)/ZnCo(2)O(4) was characterized by structural, optical, and photochemical properties and the photocatalyst decoloration of indigo carmine. Mott–Schottky plots proved a heterojunction formed between n-Bi(2)S(3) and p-ZnCo(2)O(4). Furthermore, the investigation of the photocurrent response indicated that the Bi(2)S(3)/ZnCo(2)O(4) 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 Bi(2)S(3) (1.02 μA cm(−2)) and ZnCo(2)O(4) (0.65 μA cm(−2)). Especially the optimized p–n Bi(2)S(3)/ZnCo(2)O(4) heterojunction with 12 wt% Bi(2)S(3) 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 Bi(2)S(3)/ZnCo(2)O(4) 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.