High-Efficiency Photo-Fenton-like Catalyst of FeOOH/g-CN for the Degradation of PNP: Characterization, Catalytic Performance and Mechanism Exploration.

The composite photocatalyst FeOOH/g-CN was prepared through thermal polycondensation and co-precipitation methods, followed by XRD, SEM and UV-vis characterization. The stability of FeOOH/g-CN was explored by the recycling test. The active species in the reaction system were investigated by the capture experiment. The results indicated that the optimal preparation condition for g-CN involved calcination at 600 °C for 4 h. XRD analysis revealed that g-CN exhibits a high-purity phase, and Fe in FeOOH/g-CN exists in a highly dispersed amorphous state. SEM analysis showed that FeOOH/g-CN has a rough surface with an irregular layered structure. Element composition analysis confirmed that the content of elements in the prepared catalyst is consistent with the theoretical calculation. FeOOH/g-CN possesses the largest specific surface area of 143.2 m/g and a suitable pore distribution. UV-vis DRS analysis showed that the absorption intensity of FeOOH/g-CN is stronger than that of g-CN. When the catalyst dosage was 1.0 g/L, the HO dosage was 4 mmol/L, the PNP initial concentration was 10 mg/L and the initial pH value was 5, the PNP removal could reach 92% in 120 min. Even after 5 cycles, the efficiency of PNP removal by FeOOH/g-CN remains nearly 80%. The capture experiment indicated that both •OH and •O play roles in the photocatalytic degradation of PNP, with •OH being more significant. These findings affirm that FeOOH has been successfully incorporated into g-CN, resulting in a conspicuous catalytic effect on the degradation of PNP in the visible light-assisted Fenton-like reaction.