Insight on the degradation of P-chlorophenol based on the Co-g-C3N4/diatomite composite photo-Fenton process

[Display omitted] •Co-doping reduces g-C3N4 photogenerated electron-hole complexation probability.•The introduction of diatomite improves the dispersion of g-C3N4.•Co-g-C3N4/DE showed a 5.3 times higher degradation efficiency than pure g-C3N4.•Co-g-C3N4/DE removed up to 98.7 % of 4-CP in 100 min.•Inferred ROS attack mechanism for 4-CP degradation using DFT calculations. The non-metallic photocatalyst g-C3N4 is characterized by non-toxicity and straightforward preparation. Still, the drawbacks of low specific surface area and fast carrier complexation rate limit its practical application in photocatalysis. In this work, Co-doped g-C3N4 was prepared on the surface of diatomite (DE) through a simple one-step calcination method and used to degrade 4-chlorophenol (4-CP). Photocatalytic experiments showed that Co-g-C3N4/DE removed up to 98.7% of 4-CP. The doping of Co could capture the photogenerated electrons, thereby reducing the recombination of photocarriers and accelerating the oxidation–reduction reaction of Co3+/Co2+ and H2O2, promoting the generation of OH. Introducing DE improved the aggregation of g-C3N4 and expanded its surface area. Moreover, the Co-g-C3N4/DE composite material exhibited a low metal leaching rate and good reusability throughout the experiments. In addition, based on DFT calculations, the ROS attack mechanism of 4-CP degradation was speculated and calculated. The final product of 4-CP was found to pose a more minor environmental threat, according to the T.E.S.T. In short, the prepared Co-g-C3N4/DE composite realized the capture of photogenerated electrons and the acceleration of photocatalytic reactions, which are expected to solve the challenges in wastewater treatment.