C–S bond induced ultrafine SnS2 dot/porous g-C3N4 sheet 0D/2D heterojunction: synthesis and photocatalytic mechanism investigation

Abstract

The construction of novel heterojunctions is precisely deemed to be an effective strategy to facilitate photo-generated carrier separation and boost charge utilization efficiency, leading to much enhanced photocatalytic activities. Herein, in situ of growing ultrafine SnS₂ nanoparticles on a porous g-C₃N₄ sheet (SnS₂/g-C₃N₄) 0D/2D heterojunction was achieved via a low-temperature solvothermal process. Combined with various characterization techniques, it is revealed that SnS₂ dots with a diameter of 3 nm distribute evenly on the surface of the g-C₃N₄ substrate with strong C–S bonds. The photocatalytic activities are evaluated by the degradation of Rhodamine B (RhB) under visible light irradiation, showing a much enhanced photodegradation efficiency of 96.8% over 105 min irradiation and an enhanced reaction rate constant (k = 3.3% min⁻¹, 8.25 and 8.05 times that of pure g-C₃N₄ and SnS₂). The improved photocatalytic activities could be ascribed to the efficient electron–hole separation of porous g-C₃N₄, which is caused by the ultrafine SnS₂ dots linked with the g-C₃N₄ substrate through C–S bonds. Therefore, the recombination efficiency is decreased. In addition, reactive active species trapping experiments prove that the superoxide radical (˙O₂⁻) and holes (h⁺) are the main active species in this photocatalytic system. The photodegradation mechanism of the SnS₂/g-C₃N₄ heterojunction is analyzed and demonstrated in detail.