Synthesis of tubular amorphous nickel-doped g-C₃N₄ catalyst via pre-assembly strategy for fenton-like oxidation of phenol in wastewater

As an environmentally friendly carrier, the non-toxic and non-hazardous nature of carbon nitride ensures that there is no secondary pollution of the environment during the application process, thus significantly enhancing the environmental sustainability of the overall process. In this study, carbon nitride was explored as a promising catalytic support for nickel doping, employing a pre-assembly strategy utilizing the bridging effect of 2-methylimidazole to introduce nickel atoms into the carbon nitride precursor uniformly. Subsequently, a tubular amorphous nickel-doped carbon nitride catalyst was successfully synthesized through a thermal polycondensation method. The material's morphological characteristics and physicochemical properties were characterized and analyzed using techniques such as XRD, TEM, and XPS. Ni/CN(4) samples exhibit the largest Fenton-like catalytic performance under neutral conditions, and the degradation of 50 mg/L phenol reaches 91.9 % within 1 h. The catalyst shows good catalytic activity within the initial pH= 4–11, and the degradation rate of phenol can still reach 85.5 % after 4 cycles of use. Free radical capture experiment and EPR results show that ¹O₂ and O₂•⁻ are the main active substances in the degradation process. The synthesized catalyst Ni/CN(4) uses 2-methylimidazole as an intermediate connecting the nickel source and supramolecular structure, so that the doped Ni can promote the directed polycondensation of the carbon nitdrive precursor, resulting in the formation of tubular structures. Nickel doping can introduce new active sites on the surface of carbon nitride, which can promote carbon nitride activated PMS to degrade phenol and have better durability in acidic or alkaline environments.