Elucidating the role of phosphorus doping in Co and Ni-loaded carbon nitride photocatalysts for nefazodone degradation

To understand the role of phosphorus doping in Co and Ni-loaded carbon nitride photocatalysts, four P-doped samples are prepared using different strategies. Morphological characterization shows that Co and Ni single atoms were prepared using a concurrent P annealing process in the presence of carbon nitride and CoNi layered double hydroxides (PA-4). In addition, structural characterization indicates that the introduced P can etch CoNi soft-templates and be doped into the coordination environment. The PA-4 structure is believed to enhance the photogenerated charge carrier transfer. The as-prepared PA-4 samples exhibit better photocatalytic activity for nefazodone (Nefa) degradation in water (99.9% within 40 ​min) than other P-doped samples. Quenching experiments indicate that O2•−, •OH, and photogenerated electrons and holes contribute to the degradation of Nefa. Analysis of the intermediate products suggests that the degradation routes primarily involve hydroxylation reactions, N-dealkylation reactions, and piperazine cracking. The findings provide an alternative strategy for the preparation of P-doped Co and Ni-loaded carbon nitride photocatalysts for contaminant degradation and elucidate the role of P doping.