Using melamine as raw material, metal-free g-C₃N₄ photocatalyst was synthesized by thermal polymerization method. After grinding the produced g-C₃N₄ and ascorbic acid (Vitamin C, V_c), the mixture was calcined at 300 °C to obtain rich O doped g-C₃N₄ (O-g-C₃N₄) materials. Some physical chemistry technologies, e.g. XRD, TG-DSC, FT-IR, Raman, XPS, SEM, TEM, BET, UV–vis DRS, PL, and photoelectrochemical test were used to characterize the catalyst. The results show that O-g-C₃N₄ possesses high O content (~10 wt%) and displays no obvious morphological change compared to g-C₃N₄. However, after O doping, its band gap energy was significantly reduced and its visible light absorption ability was largely boosted. In addition, the CO bond generated by O doping can act as a strong electron trap centers and effectively promote the separation of photo-generated electrons and holes pair. The prepared O-g-C₃N₄ displayed high performance for aqueous Cr(VI) removal. Under xenon lamp illumination for 150 min, over 90%Cr(VI) can be reduced over O-g-C₃N₄. Moreover, in Cr(VI) removal, O-g-C₃N₄ appeared high photocatalytic stability and high compatibility with common anions (SO₄²⁻, CO₃²⁻, Cl⁻) and cations (Ca²⁺, Na⁺, K⁺) in water.

以三聚氰胺为原料，通过热聚合法合成了无金属的g -C ₃ N ₄光催化剂。将产生的g -C ₃ N ₄和抗坏血酸（维生素C，V _c）研磨后，将混合物在300°C下煅烧，得到富含O的g -C ₃ N ₄（O- g -C ₃ N ₄）。材料。一些物理化学技术，例如XRD，TG-DSC，FT-IR，拉曼，XPS，SEM，TEM，BET，UV-vis DRS，PL和光电化学测试被用来表征催化剂。结果表明，O- g -C₃ N ₄具有较高的O含量（〜10 wt％），与g -C ₃ N ₄相比，无明显的形态变化。但是，O掺杂后，其带隙能量显着降低，可见光吸收能力大大提高。此外，由O掺杂产生的C O键可以充当一个强电子陷阱中心，并有效地促进光生电子和空穴对的分离。制备的O- g -C ₃ N ₄具有去除水中Cr（VI）的高性能。在氙气灯下照明150分钟，与O- g -C ₃ N _4相比，可减少90％以上的Cr（VI）。此外，在铬（VI）的去除，O-克-C ₃ Ñ ₄出现高的光催化的稳定性和与普通高阴离子的相容性（SO ₄ ^2-，CO ₃ ^2-，氯^- ）和阳离子（钙²⁺，钠⁺，K ⁺）在水中。