Visible-light-driven double-shell SnIn4S8/TiO2 heterostructure with enhanced photocatalytic activity for MO removal and Cr(VI) cleanup

Construction and design the various heterojunction structures are effective and promising strategies to improve the photocatalytic performances of semiconductors. In this work, a novel visible-light-driven SnIn4S8 nanosheet/TiO2 hollow sphere (SISTOHS) heterojunction with the intimate contact structure was successfully constructed by the facile hydrothermal process. The as-prepared SISTOHS heterostructures displayed outstanding photo catalytic removal activities of methyl orange (MO) and Cr (VI). The optimized sample SISTOHS2 presented the highest photodegradation efficiency of MO (90.08%) and photoreduction efficiency of Cr (VI) (94.44%) within 60 min. Significantly, the rate constants of photodegradation for MO and photoreduction for Cr (VI) over SISTOHS2 were 15.03 and 28.39 folds as high as those of TiO2 hollow spheres, 2.37 and 4.02 folds as high as those of SnIn4S8 nanosheets, respectively. Through the systemic characterizations, the improvement of photocatalytic performance could be not only contributed to the intimate contact double-shell interface introduced a strong interaction between SnIn4S8 and TiO2 to accelerate the separation and migration of charge carriers, but also the increased visible light harvesting ability and abundant reactive sites ensuring the excellent photoactivity. The photocatalytic mechanism of typical type-II heterojunction was discussed in-depth. This work will provide a favorable theoretical and practical experience of designing TiO2 related photocatalyst for wastewater purification.

Automated summary

A novel visible-light-driven SnIn4S8 nanosheet/TiO2 hollow sphere heterojunction with intimate contact structure was successfully constructed by hydrothermal process. The SISTOHS heterostructures exhibited outstanding photocatalytic performance and the optimized sample SISTOHS2 showed the highest photodegradation and photoreduction efficiencies. The rate constants of photodegradation and photoreduction over SISTOHS2 were significantly higher than those of the control samples. The systemic characterizations revealed that the improvement of photocatalytic performance was attributed to the double-shell interface, which enhanced the interaction between SnIn4S8 and TiO2, as well as the increased visible light harvesting ability and abundant reactive sites.