Almost 100 % Peroxymonosulfate Conversion to Singlet Oxygen on Single‐Atom CoN₂₊₂ Sites

Abstract

Single‐atom CoN4 active sites have demonstrated excellent efficiency in peroxymonosulfate activation. However, the identification of CoN4 active sites and the detailed singlet oxygen generation mechanism in peroxymonosulfate activation remains ambiguous. We demonstrate a strategy to regulate the generation of reactive oxygen species by atomically dispersed cobalt anchored on nitrogen‐doped carbon. As indicated by experiment and DFT calculations, CoN2+2 was the active site and singlet oxygen was the predominant reactive oxygen species with a proportion of 98.89 %. Spontaneous dissociation of adsorbed peroxymonosulfate on the CoN2+2 active sites was energetically unfavorable because of the weakly positive Co atoms and CoN2+2 coordination, which directed PMS oxidation by a non‐radical pathway and with simultaneous singlet oxygen generation. The generated singlet oxygen degraded several organic pollutants with high efficiency across a broad pH range.

Natural mineral modulated single atom catalyst for effective water treatment

“…In addition, the electron density difference proves the electrons transfer from PMS to Co single atom active center in both CoN 4 and CoSi 1 N 3 moieties (Fig. 5e and 5f) 14 . The process of electron transfer is further con rmed by the obviously increased cathodic current densities for the p-CoSi 1 N 3 @D electrode with the addition of PMS in the LSV analysis (Supplementary Fig.…”

“…•− and • OH) and nonradical ( 1 O 2 ) reaction processes generally contribute to the pollutant degradation during PMS activation 20,48 . However, which one dominates is still not clear even in the highly similar Co SACs/PMS systems 14,[20][21][22]48 . Herein, the involved reaction mechanisms were discriminated by in situ EPR and scavenging experiments.…”

“…Catalyst structure during PMS activation. The electron transfer between PMS molecules and Co active centers was regarded as the rate determining process in the nonradical pathway 14,18 . To gain further insights into the relationship between electron transfer, PMS activation properties and spatial coordination con guration of cobalt single atom active sites, rst principles density-function theory (DFT) calculations were further carried out.…”

“…The Co isolated single atoms grafted to a carbon basal plane with CoN x moieties have been proven as desirable catalysts for PMS activation 11,14,18,[20][21][22] . In most cases, the reactive site structure was reported as the planar four-coordinated con guration of CoN 4 moieties 12,13,[23][24][25] .…”

“…Cobalt oxides such as Co 3 O 4 can address above issues, but the relatively low activation e ciency (turnover frequencies (TOF) per Co atom basis) compared to Co 2+ remains challenging [7][8][9][10] . In recent years, Co single atom catalysts (SACs), as one of the most emerging kinds of heterogeneous catalysts, possess special electronic structure, utmost Co atom utilization e ciency, and uniformly isolated Co active sites [11][12][13][14][15][16][17] . Such unique properties make Co SACs an attractive platform to bridge the gap between homogeneous and heterogeneous PMS activation 1,11,[17][18][19][20] .…”