Sulfur-nitrogen synergistic active sites enable continuous and fast removal of organic pollutants in practical water matrix

Abstract

The rational design of active sites in nanocarbons are the long-term pursuit for their practical applications. However, N, as the most potential active site, still encounters the problems of low atom utilization efficiency and stability in practical environmental remediation. Herein, we successfully constructed synergistic active sites consisting of graphitic N, pyridinic N, and thiophene S in heavy S, N co-doped hollow graphene spheres (HSNGS). The HSNGS exhibited exceptional efficiency in degrading tetracycline in real water, with a turnover frequency of 6.24 min−1, which is among the highest reported. Moreover, tetracycline dissolved in practical water could be continuously and rapidly eliminated by passing through a column filled with HSNGS, maintaining its high performance even after 40 consecutive cycles. In the synergistic active sites, graphitic N and pyridinic N species accepted electrons from peroxymonosulfate, generating singlet oxygen for tetracycline degradation. Simultaneously, thiophene S coordinated with metal ions present in the practical water, synergistically enhancing the degradation of tetracycline. Additionally, the coordinated metal ions provided protection for the synergistic active sites during peroxymonosulfate activation, preventing their oxidation and enabling the continuous and rapid degradation of tetracycline. This work opens up possibilities for the industrial application of nanocarbon materials in environmental remediation.