The in-situ generation of ClO• by single- and dual-atom catalysis of chloride ions to degrade sulfonamide antibiotics: A DFT study

Abstract

Single- (SACs) and dual-atom catalysts (DACs) are recognized as promising electrochemical materials. However, their application potential in the water treatment with the presence of chloride ions (the most common water matrice) still needs to be investigated. Thus, the first-principles calculation was used to investigate the electrocatalytic activation of Cl− and micropollutant degradation mechanisms by four kinds of metal-embedded nitrogen-doped carbon materials (M-N-C). The results show that the average Cl− adsorption energies (Eads) in different configurations follow the order of M2N6-a < M2N8 < MN4 < M2N6-b. The average Eads of SACs and DACs doped with different metal atoms follow the order of Fe < Co < Ni and Fe2 < FeNi < FeCo < CoNi ≈ Co2 < Ni2, respectively. The chlorine evolution reactions (CER) on the FeN4 and Fe2N6-a in neutral water were revealed as Cl− → *Cl → HClO* → free HClO, and HClO will rapidly generate ClO• to degrade target pollutants. The generated ClO• exhibits high reactivity towards sulfanilamide antibiotics (SAs) with the reaction rate constants of 1.78 × 108–6.86 × 109 M−1 s−1, indicating the high feasibility of ClO• in SAs purification from wastewater. This study provides mechanistic insights into the electrocatalytic generation of ClO• and its application in removing contaminants of emerging concern in M-N-C-supported electrochemical advanced oxidation processes.