【目的】石墨相碳氮化合物(g-C3N4,GCN)在光催化降解水中有机污染物方面被广泛应用。传统的GCN由于比表面积低和活性位点少等问题限制了其实际应用。【方法】为改良氮化碳性能,以尿素为前驱体,采用热聚合法成功制备光催化剂氮化碳(PCN),利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱(FT-IR)等表征了PCN的形貌、元素组成、晶体结构、电化学性能等,并探究了其在模拟太阳光下对目标污染物双氯芬酸(DCF)的降解行为和机制。【结果】结果表明,PCN的比表面积(133.963m2/g)明显高于传统GCN(2.605m2/g),约为GCN的67倍。PCN(0.20g/L)在pH为5时10min内即可实现DCF(10mg/L)100%的催化降解。自由基淬灭实验证实超氧自由基(•O2−)和羟基自由基(•OH)是主要的活性氧(ROSs)物种,通过基于福井指数的密度泛函理论(DFT)计算并结合中间产物的测定确定了DCF的降解路径。可重复利用实验表明,PCN能保持较高的稳定性,具有广阔的应用前景。

【Purposes】 Carbon nitrides in graphite phase (g-C N , GCN) have been widely used  in photocatalytic degradation of organic pollutants in water. However, traditional GCN is limited in  practical application because of its low specific surface area and few active sites. 【Methods】 In this  study, photocatalyst (PCN) was prepared by thermal polymerization method by using urea as precur‐ sor. PCN was characterized by X-ray diffraction, scanning electron microscopy, transmission electron  microscopy, and Fourier transform infrared spectroscopy. Diclofenac (DCF) was selected as target pol‐ lutant to study photocatalytic degradation. 【Findings】 The results show that the specific surface area  of PCN (133.963 m /g) is significantly higher than that of GCN (2.605 m /g), about 67 times that of  GCN. PCN(0.20 g/L) can achieve 100% catalytic degradation of DCF(10 mg/L) within 10 min at pH  of 5. Free radical quenching experiments confirm that superoxide radical (•O ) and hydroxyl radical  (•OH) are the primary reactive oxygen species. The degradation pathway of DCF is determined by the  Fukui index-based density functional theory and the determination of intermediates. The experimental  results show that PCN has high stability and has promising applications in the field of photocatalytic  degradation of emerging pollutants in water.