Fenton-like activity and pathway modulation via single-atom sites and pollutants comediates the electron transfer process

Abstract

The studies on the origin of versatile oxidation pathways toward targeted pollutants in the single-atom catalysts (SACs)/peroxymonosulfate (PMS) systems were always associated with the coordination structures rather than the perspective of pollutant characteristics, and the analysis of mechanism commonality is lacking. In this work, a variety of single-atom catalysts (M-SACs, M: Fe, Co, and Cu) were fabricated via a pyrolysis process using lignin as the complexation agent and substrate precursor. Sixteen kinds of commonly detected pollutants in various references were selected, and their ln k obs values in M-SACs/PMS systems correlated well ( R 2 = 0.832 to 0.883) with their electrophilic indexes (reflecting the electron accepting/donating ability of the pollutants) as well as the energy gap ( R 2 = 0.801 to 0.840) between the pollutants and M-SACs/PMS complexes. Both the electron transfer process (ETP) and radical pathways can be significantly enhanced in the M-SACs/PMS systems, while radical oxidation was overwhelmed by the ETP oxidation toward the pollutants with lower electrophilic indexes. In contrast, pollutants with higher electrophilic indexes represented the weaker electron-donating capacity to the M-SACs/PMS complexes, which resulted in the weaker ETP oxidation accompanied with noticeable radical oxidation. In addition, the ETP oxidation in different M-SACs/PMS systems can be regulated via the energy gaps between the M-SACs/PMS complexes and pollutants. As a result, the Fenton-like activities in the M-SACs/PMS systems could be well modulated by the reaction pathways, which were determined by both electrophilic indexes of pollutants and single-atom sites. This work provided a strategy to establish PMS-based AOP systems with tunable oxidation capacities and pathways for high-efficiency organic decontamination.

Prehydrated Electrons Activated by Continuous Electron Transfer Stemmed from Peracetic Acid Homolysis Mediated by Diamond Surface Defects for Enhanced PFOA Destruction

“…To investigate the reactive species and reaction mechanism of the PAA/ND system in alkaline water samples, reference is made to recent research by Guo et al 34 They established that electron transfer and free radicals oxidation pathways could simultaneously occur within the same AWT system, influenced by the energy gaps between the catalytic oxidation complexes and pollutants and the electrophilic index of organic pollutants.…”

“…To investigate the reactive species and reaction mechanism of the PAA/ND system in alkaline water samples, reference is made to recent research by Guo et al They established that electron transfer and free radicals oxidation pathways could simultaneously occur within the same AWT system, influenced by the energy gaps between the catalytic oxidation complexes and pollutants and the electrophilic index of organic pollutants. Based on this, it was initially hypothesized that the efficiency increase is attributable to the nonradical electron transfer contribution during the decomposition of PAA, similar to the degradation of aromatic compounds by PAA-based AWT induced by the electron transfer from the target substance to free radicals, as proposed by Kim et al The activation of PAA and the degradation of PFOA involve electron transfer from PFOA (an electron donor) to PAA (an electron acceptor), with ND acting as an efficient electron transfer mediator.…”

New Insights into Photo-Fenton Chemistry: The Overlooked Role of Excited IronIII Species

“… However, the issue of sluggish dynamics of Fe II generation still limits the practical applications of Fenton technique (eqs and , Text S1 and Figure S1). − F e ( I I ) + H 2 O 2 → F e ( I I I ) + • O H + normalO normalH − goodbreak0em3em⁣ k = 80 .25em normalM − 1 .25em s − 1 F e ( I I I ) + H 2 O 2 → F e ( I I ) + normalH normalO 2 • + H + goodbreak0em1em⁣ k = 9.1 × 10 − 7 .25em normalM − 1 .25em s − 1…”

“… However, the issue of sluggish dynamics of Fe II generation still limits the practical applications of Fenton technique (eqs and , Text S1 and Figure S1). − …”

Hydrogen Peroxide as an Ideal Electron Donor for Long-Lasting Fenton Chemistry: Strong Enhancement of Fe(III) Activity by Heteroatom-Doped Nanocarbons

“…Although conventional Fenton oxidation can be enhanced using electron sacrificial agents to promote Fe(III) reduction, there are inherent disadvantages such as poor stability, recovery difficulties, secondary pollution, and high economic costs. 11 In Fenton chain reactions, Fe(III) can be slowly reduced by reacting with H 2 O 2 (eq 2), indicating the ability of H 2 O 2 to reduce Fe(III). Therefore, the inherent drawbacks of enhancing Fenton oxidation with reducing species would be effectively avoided if the ability of Fe(III) to oxidize H 2 O 2 is enhanced.…”