Promoted peroxydisulfate activation by nitrogen-doped carbon embedding iron on a nickel foam cathode: Performance, mechanism and relationship between C[dbnd]O and 1O2 generation

Abstract

Nitrogen doped carbon embedding iron on a nickel foam (xN-C@Fe/NF) cathode was prepared and used to activate peroxydisulfate (PDS) for organic pollutant degradation. Benefiting from N doping-induced CO content increasing, which possessed good electron-withdrawing properties from Fe and the cathode, the optimum 3 NC@Fe/NF cathode displayed superior model organic pollutant (sulfamethoxazole, SMX) removal efficiency. Specifically, almost 100 % SMX removal efficiency was achieved within 15 min. It was found that the contribution of singlet oxygen (1O2) to SMX degradation gradually became more important with increasing N doping. On the basis of the semiquantitative and quantitative structure–activity relationship and density functional theory (DFT) calculation, it is conclusively identified that CO in the NC@Fe/NF tuned by the doped pyrrolic N and graphitic N are the core catalytic active sites for PDS activation, which was further evidenced by the high linear correlation (R2 of 0.983) between CO content and 1O2 yield. Furthermore, the 3 NC@Fe/NF cathode displayed attractive practical application prospect because of its wide pH applicability, good anti-interference ability, stable catalytic performance and universal adaptability for multiple organics removal. This study not only established a high-efficiency method for green remediation of actual polluted water but also developed valuable insight for discriminating the catalytic active sites of the cathode for PDS activation.