Single-Atom Fe Catalyst Outperforms Its Homogeneous Counterpart for Activating Peroxymonosulfate to Achieve Effective Degradation of Organic Contaminants

Abstract

Recently, reactive iron species (RFeS) have shown great potential for the selective degradation of emerging organic contaminants (EOCs). However, the rapid generation of RFeS for the selective and efficient degradation of EOCs over a wide pH range is still challenging. Herein, we constructed FeN4 structures on a carbon nanotube (CNT) to obtain single-atom catalysts (FeSA-N-CNT) to generate RFeS in the presence of peroxymonosulfate (PMS). The obtained FeSA-N-CNT/PMS system exhibited outstanding and selective reactivity for oxidizing EOCs over a wide pH range (3.0–9.0). Several lines of evidences suggested that RFeS existing as an FeN4O intermediate was the predominant oxidant, while SO4 ·– and HO· were the secondary oxidants. Density functional theory calculation results revealed that a CNT played a key role in optimizing the distribution of bonding and antibonding states in the Fe 3d orbital, resulting in the outstanding ability of FeSA-N-CNT for PMS chemical adsorption and activation. Moreover, CNT could significantly enhance the reactivity of the FeN4O intermediate by increasing the overlap of electrons of the Fe 3d orbital, O 2p orbital, and bisphenol A near the Fermi level. The results of this study can advance the understanding of RFeS generation in a heterogeneous system over a wide pH range and the application of RFeS in real practice.

Carbon Nitride Supported High‐Loading Fe Single‐Atom Catalyst for Activation of Peroxymonosulfate to Generate 1O2 with 100 % Selectivity

“…In contrast, the rate of degradation of 4‐CP changed significantly when diverse anions, cations, and NOM were introduced into the Fe NP /CN activated PMS system (Figures 4 b and S26), which shows that the degradation process of 4‐CP with SO 4 .− and . OH radicals is easily disturbed by the environmental substances [30] . More importantly, Fe 1 /CN achieved similar rates of degradation of 4‐CP in natural (tap water, the Poyang Lake water, and the Yangtze River water) and deionized waters (Figure 4 d), indicating its excellent practical application prospects.…”

Facile Synthesis of Atomic Fe‐N‐C Materials and Dual Roles Investigation of Fe‐N4 Sites in Fenton‐Like Reactions

“…Usually, in a system dominated by high-valent Fe, the oxidation process will be ended with PMSO converted into PMSO 2 , and further degradation will not happen. [50][51][52] Therefore, we speculate that this process is not dominated by high-valence Fe.…”

Carbon Nitride Supported High‐Loading Fe Single‐Atom Catalyst for Activation of Peroxymonosulfate to Generate 1O2 with 100 % Selectivity

“…In contrast, the rate of degradation of 4-CP changed significantly when diverse anions, cations, and NOM were introduced into the Fe NP /CN activated PMS system (Figures 4 b and S26), which shows that the degradation process of 4-CP with SO 4 C À and COH radicals is easily disturbed by the environmental substances. [30] More importantly, Fe 1 /CN achieved similar rates of degradation of 4-CP in natural (tap water, the Poyang Lake water, and the Yangtze River water) and deionized waters (Figure 4 d), indicating its excellent practical application prospects. As shown in Figure S27, the cyclic tests demonstrated that Fe 1 /CN is more stable than Fe NP /CN during the activation of PMS for the degradation of 4-CP.…”