Highly dispersive Ru confined in porous ultrathin g-C3N4 nanosheets as an efficient peroxymonosulfate activator for removal of organic pollutants

Ru species were loaded on a two-dimensional (2D) material of graphitic carbon nitride (2D g-C3N4) to serve as the efficient AOP catalysts. The catalytic activity was closely related to the dispersion degree of Ru, as deter-mined by the inherent nanoarchitecture of the supporting material. Ultrathin g-C3N4 nanosheets with a unique porous structure were fabricated by further thermally oxidizing and etching bulk g-C3N4 (bCN) in air. Homo-geneous dispersion of Ru species was successfully achieved on the porous few-layered g-C3N4 nanosheets (pCN) by stirring, washing, freeze drying and annealing processes to obtain Ru-pCN catalysts, whereas bCN or multi-layered g-C3N4 (mCN) led to the aggregation of Ru nanoparticles in Ru-bCN and Ru-mCN materials. The con-ventional impregnation method also caused the resulting Ru-pCN-imp catalyst with undesirable Ru aggregation in spite of employing pCN. The optimal 4.4Ru-pCN removed 100% of 2,4,6-trichlorophenol (TCP) within only 3 min, superior to its counterpart samples, and exhibited remarkable degradation efficiencies for methyl orange, neutral red, 4-chlorophenol, tetracycline and oxytetracycline. Mechanistic studies suggested that four radicals, e. g., H, SO4 center dot-, O2 center dot and O-1(2) were generated during the peroxymonosulfate (PMS) activation, in which SO4 center dot--and O-1(2) played a major role.

Automated summary

Ru species loaded on 2D graphitic carbon nitride material exhibited excellent catalytic activity for organic compound removal. The dispersion degree of Ru was crucial to the catalytic performance, achieved by optimizing the preparation process and obtaining Ru-pCN catalysts with homogeneous dispersion of Ru species.