Fast diffusion kinetics improves electron transfer regime selectivity to boost peroxymonosulfate activation

Abstract

Electron transfer process (ETP) is barely influenced by half-life and migration distance in peroxymonosulfate (PMS) activation because it directly extracts electrons from pollutants for oxidation. However, the enhanced ETP selectivity is still challenging due to the poor mass transfer of PMS and pollutant. In this work, 2D porous N-doped carbon (PNC) with high reactant diffusion kinetics and multiple diffusion modes was designed to induce the interlayer confinement for efficient PMS activation with elevated ETP selectivity. Taking tetrabromobisphenol A as target pollutant, the confined PNC/PMS system achieved significantly enhanced PMS activation performance with the selectivity of ETP up to 97.8%. The vertical mass transfer of reactants into the inner interlayer space of the catalysts was proved to be promoted by the construction of molecule tunnels according to a diffusion model. Density functional theory calculations indicated that the subsequently triggered interlayer confinement facilitated the co-adsorption of PMS/pollutant on the interlayer surface and narrowed the energy gap of charge migration, resulting in enhanced PMS activation performance and ETP selectivity. Benefiting from the almost 100 % ETP selectivity, the confined PNC/PMS system exhibited substantially increased PMS utilization efficiency, admirable anti-interference ability towards various water matrices as well as long-term stability in a continuous-flow reactor. This work provides a new protocol for efficient and selective PMS activation by interlayer confinement in water remediation.