Effective promotion of spacial charge separation of dual S-scheme (1D/2D/0D) WO3@ZnIn2S4/Bi2S3 heterojunctions for enhanced photocatalytic performance under visible light

Herein, a new type of hierarchical dual S-scheme heterojunction, W@ZIS/Bi2S3, was well-designed for the photocatalytic elimination of Cr (VI). In order to prevent the fast recombination of photoinduced electron-hole pairs, ZnIn2S4 , as a "bridge " has a strong interaction with both WO3 and Bi2S3, facilitating charge migration and spatial separation for accuracy regulation of redox centers, simultaneously promoting the catalytic oxidation and the reduction capability. The optimized W@ZIS/Bi2S3 composite, with the hierarchical structure, larger surface area and numerous nanoscale active sites, exhibited excellent adsorption and photocatalytic capacity. High efficiency (100%) of Cr (VI) (10 mg/L) reduction could be obtained within 30 min, with its photocatalytic rate ratio about 8.09 times higher than pure ZnIn2S4 and 2.04 times higher than W@ZIS-1.4, respectively. The optimized W@ZIS/Bi2S3 composite exhibited perfect stability and recyclability. Meanwhile, the promoted activity of TC oxidation has also been obtained. Dual S-scheme heterojunction and hierarchical structure provided a promising general method for catalyst design, giving new insights into the working mechanism of ternary heterojunction.