High-Efficiency Photo-Fenton-like Catalyst of FeOOH/g-C 3 N 4 for the Degradation of PNP: Characterization, Catalytic Performance and Mechanism Exploration.

The composite photocatalyst FeOOH/g-C ₃ N ₄ was prepared through thermal polycondensation and co-precipitation methods, followed by XRD, SEM and UV-vis characterization. The stability of FeOOH/g-C ₃ N ₄ 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-C ₃ N ₄ involved calcination at 600 °C for 4 h. XRD analysis revealed that g-C ₃ N ₄ exhibits a high-purity phase, and Fe in FeOOH/g-C ₃ N ₄ exists in a highly dispersed amorphous state. SEM analysis showed that FeOOH/g-C ₃ N ₄ 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-C ₃ N ₄ possesses the largest specific surface area of 143.2 m ² /g and a suitable pore distribution. UV-vis DRS analysis showed that the absorption intensity of FeOOH/g-C ₃ N ₄ is stronger than that of g-C ₃ N ₄ . When the catalyst dosage was 1.0 g/L, the H ₂ O ₂ 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-C ₃ N ₄ remains nearly 80%. The capture experiment indicated that both •OH and •O ₂ ^- play roles in the photocatalytic degradation of PNP, with •OH being more significant. These findings affirm that FeOOH has been successfully incorporated into g-C ₃ N ₄ , resulting in a conspicuous catalytic effect on the degradation of PNP in the visible light-assisted Fenton-like reaction.