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

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 (O-center dot(2)-) 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.