Synthesis of Sulfur Vacancy-Bearing InS/CuInS Microflower Heterojunctions via a Template-Assisted Strategy and Cation-Exchange Reaction for Photocatalytic CO Reduction.

The synthesis of the accurate composition and morphological/structural design of multielement semiconductor materials is considered an effective strategy for obtaining high-performance hybrid photocatalysts. Herein, sulfur vacancy (Vs)-bearing InS/CuInS microflower heterojunctions (denoted Vs-InS/CuInS) were formed in situ using InS microsphere template-directed synthesis and a metal ion exchange-mediated growth strategy. Photocatalysts with flower-like microspheres can be obtained using hydrothermally synthesized InS microspheres as a template, followed by Ostwald ripening growth during the metal cation exchange of Cu and In. The optimal heterostructured Vs-InS/CuInS microflowers exhibited CO and CH evolution rates of 80.3 and 11.8 μmol g h, respectively, under visible-light irradiation; these values are approximately 4 and 6.8 times higher than those reported for pristine InS, respectively. The enhanced photocatalytic performance of the Vs-InS/CuInS catalysts could be attributed to the synergistic effects of the following factors: (i) the constructed heterojunctions accelerate charge-carrier separation; (ii) the flower-like microspheres exhibit highly uniform morphologies and compositions, which enhance electron transport and light harvesting; and (iii) the vs. may trap excited electrons and, thus, inhibit charge-carrier recombination. This study not only confirms the feasibility of the design of heterostructures on demand, but also presents a simple and efficient strategy to engineer metal sulfide photocatalysts with enhanced photocatalytic performance.