Activity Trends and Mechanisms in Peroxymonosulfate‐Assisted Catalytic Production of Singlet Oxygen over Atomic Metal‐N‐C Catalysts

Abstract

We synthesized a series of carbon‐supported atomic metal‐N‐C catalysts (M‐SACs: M=Mn, Fe, Co, Ni, Cu) with similar structural and physicochemical properties to uncover their catalytic activity trends and mechanisms. The peroxymonosulfate (PMS) catalytic activity trends are Fe‐SAC>Co‐SAC>Mn‐SAC>Ni‐SAC>Cu‐SAC, and Fe‐SAC displays the best single‐site kinetic value (1.65×105 min−1 mol−1) compared to the other metal‐N‐C species. First‐principles calculations indicate that the most reasonable reaction pathway for 1O2 production is PMS→OH*→O*→1O2; M‐SACs that exhibit moderate and near‐average Gibbs free energies in each reaction step have a better catalytic activity, which is the key for the outstanding performance of Fe‐SACs. This study gives the atomic‐scale understanding of fundamental catalytic trends and mechanisms of PMS‐assisted reactive oxygen species production via M‐SACs, thus providing guidance for developing M‐SACs for catalytic organic pollutant degradation.

In Situ Hydroxylation of a Single-Atom Iron Catalyst for Preferential 1O2 Production from H2O2

“…It is very recently recognized that the microstructure (e.g., aggregation state, coordination circumstance) of a Fenton catalyst significantly affects the production of 1 O 2 in Fenton-like reactions. Single-atom catalysts (SACs) with highly dispersed metal atoms have exhibited distinguished selectivity and efficiency in many catalytic reactions compared with traditional catalysts. − Recent studies demonstrate that in a Fenton-like reaction initiated by Fe- or Co-SACs, not only the enhanced degradation rate of organic pollutants but also the regulated generation of ROS is achieved. ,, For instance, in peroxymonosulfate (PMS)-based Fenton-like reactions, Gao et al reported that compared with Fe 2 O 3 nanoparticles or Co-SACs, Fe-SACs embedded in a C 3 N 4 support favored the oxidative transformation of PMS to SO 5 ·– and 1 O 2 , while Zhan et al. demonstrated that the coordination circumstance of Co-SACs determined the selectivity between the generation of SO 5 ·– /·OH and SO 5 ·– / 1 O 2 .…”

Nanoscale zerovalent copper (nZVC) catalyzed environmental remediation of organic and inorganic contaminants: A review

“…In studies, tert-butyl alcohol (TBA) inhibits hydroxyl radicals ( . OH) ( Qi et al., 2016 ; Wang et al., 2019 ), superoxide dismutase (SOD) inhibits superoxide anions (O 2 .- ) ( Dror et al., 2020 ), sodium azide (NaN 3 ) inhibits singlet oxygen ( 1 O 2 ) ( Gao et al., 2021 ), catalase (CAT) was used to identify hydrogen peroxide H 2 O 2 ( Shen et al., 2017 ), combination of isopropanol with TBA was used to ascertain the type of hydroxyl radical in degradation process ( Ma et al., 2018 ) etc.

Figure 3 Schematic of various mechanisms involved in nZVC mediated contaminant removal processes.

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A Hybrid Subnano Cluster Electrocatalysis Process for Recalcitrant Wastewater Treatment

“…Then 2.625 mM H 2 O 2 was introduced to start the Fenton-like reaction at a rotation speed of 200 rpm. The effects of different catalysts (FeN x , x = 0.5-2.0), H 2 O 2 concentrations (0.875-3.5 mM), pH (3)(4)(5)(6)(7)(8)(9)(10)(11), and catalyst contents (1.0-5.0 mg) on system performance were also studied. For the degradation of synthetic dye wastewater, 200 µL solution was withdrawn at fixed time intervals and mixed with 100 µL methanol and then immediately measured on a microplate reader (Synergy™ HTX) at different wavelengths (MB, 665 nm; MeB, 570 nm; TB, 635 nm; MO, 465 nm; OG, 475 nm).…”

“…•− , Cl • , and 1 O 2 ) via activating various oxidants, have been considered efficient and eco-friendly technologies for wastewater treatment and subsurface contamination remediation [1][2][3]. For example, due to the high activity and non-selectivity of • OH (k = 10 9 M − 1 s − 1 ), Fenton or Fenton-like reactions can oxidize numerous toxic and stubborn contaminants and finally mineralize them into harmless molecules (CO 2 and H 2 O) [4,5].…”

“…Unfortunately, they do not truly break through the pH and real-world limitations, significantly hindering their large-scale applications [11,12]. On the one hand, the adopted acidic conditions can cause fast leaching of metal ions, while the formation of sludge and the deactivation of • OH may occur at high pH [3,13]. On the other hand, various types of components in actual wastewater can slow down the Fenton reaction by covering the active sites, competing for H 2 O 2 utilization, and quenching…”