P/N co-doped carbon sheet for peroxymonosulfate activation: Edge sites enhanced adsorption and subsequent electron transfer

A controllable synthetic route of carbon nanosheets co-doped with phosphorus and nitrogen was developed by pyrolysis of a supermolecular aggregate of self-assembled melamine, phytic acid, and carbon sheet. The as-prepared catalyst has shown a substantially increased efficiency for peroxymonosulfate (PMS) activation in the degradation of tetracycline (TC). The roles of dopants and edge sites were systematically investigated by both experimental characterizations and theoretical simulations. Compared with the undoped catalyst, the P/N co-doped catalyst has substantially enhanced the adsorption of PMS/TC and the subsequent electron transfer process, which is recognized as the dominant nonradical mechanism. Consequently, an efficient catalytic activity was obtained for the degradation of TC as well as other pollutants even under high salinity (500 mM) and high concentration wastewater (500 ppm). This work not only presents a non-metallic carbocatalyst with high catalytic activity for extensive environmental remediation, but also provides new insights into the edge P/N co-doping effects on the electron-transfer dominated nonradical activation of PMS.