Novel β-In2.77S4 nanosheet-assembled hierarchical microspheres: synthesis and high performance for photocatalytic reduction of Cr(vi)

Abstract

A novel nanosheet-assembled hierarchical sulfur-deficient β-In_2.77S₄ microsphere photocatalyst was prepared via a facile hydrothermal method. The phase evolution and possible formation mechanism of the nanosheet-assembled hierarchical β-In_2.77S₄ microspheres have been explored by virtue of temperature- and time-dependent experiments. The results demonstrated that the β-In_2.77S₄ microspheres were composed of many thin nanosheets, and underwent the Oswald ripening and self-assembly processes. This unique hierarchical structure showed faster charge separation efficiency of photogenerated electron–hole pairs. It was found that the product synthesized under suitable hydrothermal conditions showed a large specific surface area (157.86 m² g⁻¹) and high visible light photocatalytic activity in the reduction of aqueous Cr(VI). The highest activity is obtained for β-In_2.77S₄ (140 °C, 24 h), over which more than 99% of Cr(VI) was reduced after 50 min. The results suggested that nanosheet-assembled hierarchical β-In_2.77S₄ microspheres have potential application in the efficient utilization of solar energy for the treatment of Cr(VI)-containing wastewater.