In this paper, sulfur doped g-C₃N₄ (S-g-C₃N₄) was successfully prepared at 500 °C for 3 h via a modified molten salt method using dicyandiamide as the main raw material, trithiocyanuric acid as the sulfur source and LiBrKCl as the reaction medium. The as-prepared SCN5.0% sample (the mass ratio of trithiocyanuric acid to dicyandiamide was 5.0%) composed of irregular flakes showed a band gap of 1.83 eV, which was narrower than that (2.55 eV) of pristine g-C₃N₄. The SCN5.0% sample also exhibited an outstanding absorption capacity of visible light. Moreover, the photodegradation rate toward methylene blue and tetracycline were respectively 10 and 20 times as high as that of bulk g-C₃N₄ prepared by conventional heating methods, confirming its superior photocatalytic performance. These results can be attributed to that the replacement of lattice nitrogen with sulfur atom tuned the electronic structure of g-C₃N₄, improved the absorption of visible light, optimized the separation of photogenerated electron-hole pairs, and consequently enhanced the photocatalytic activity of g-C₃N₄. Moreover, the trapping experiments implied that hole (h⁺) and superoxide radical (·O²⁻) were the main active species in the process of photodegradation.

本文以双氰胺为主要原料，三硫氰尿酸为硫源，LiBr KCl为硫源，采用改良熔盐法，在500℃下3h成功制备了硫掺杂gC ₃ N ₄ (SgC ₃ N ₄ )。反应介质。由不规则薄片组成的S CN5.0% 样品（三硫氰尿酸与双氰胺的质量比为 5.0%）显示带隙为 1.83 eV，比原始 gC ₃ N ₄的带隙（2.55 eV）窄. SCN5.0% 样品还表现出出色的可见光吸收能力。此外，对亚甲蓝和四环素的光降解率分别是通过常规加热方法制备的块状 gC ₃ N _{4 的}10 和 20 倍，证实了其优越的光催化性能。这些结果可归因于用硫原子取代晶格氮调整了 gC ₃ N ₄的电子结构，提高了对可见光的吸收，优化了光生电子-空穴对的分离，从而提高了 gC 的光催化活性₃ N ₄。此外，诱捕实验表明孔 (h ⁺)和超氧自由基(·O ^2- )是光降解过程中的主要活性物质。