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By rationally adjusting the coordination environment and constructing the more electron‐enriched active site in single‐atom catalysts, the effect of heterogenous peroxymonosulfate (PMS)‐based Fenton‐like reactions can be effectively improved, yet remains a severe challenge. In this study, the electron‐rich Ru dual‐atom site is successfully immobilized onto N‐doped carbon (Ru2N6‐C) for PMS activation in water purification. The presence of electron‐rich Ru dual‐atom sites not only provides more electrons for PMS but also facilitates the formation of a Yeager adsorption configuration on the catalyst surface, which enhances O─O bond cleavage and leads to an increase in •SO4− and •OH generation. Moreover, the Ru2N6‐C catalyst exhibits exceptional durability and reliability, achieving an ultra‐high efficiency with a turnover frequency of 153.95 min−1 M−1 for the naproxen degradation. A membrane reactor is further developed for the purification of wastewater, which is expected to provide a viable approach to controlling water pollution through the design of metal dual‐atom sites carbon‐based catalysts. [ABSTRACT FROM AUTHOR]

In the current work, a novel Co-Fe bimetallic immobilized cellulose hydrogel bead (CoFeO@CHB) was prepared via in situ chemical precipitation followed by heat treatment and applied for tetracycline (TC) degradation in the presence of peroxymonosulfate (PMS). The characterization results indicated that the Co-Fe particles were evenly distributed within the porous cellulose hydrogel beads, without affecting their morphologies or crystal structures. During the TC degradation, the CoFeO@CHB/PMS system showed a high resistance and stability to different water bodies, and the common anions and natural organic matters showed a limited effect on TC degradation. The chemical quenching experiments (using chemicals to react with specific reactive species) as well as electron paramagnetic resonance (EPR) results showed that CoFeO@CHB can effectively active PMS to generate multiple reactive oxygen species (ROS, such as SO4•−, •OH and 1O2), in which the 1O2-dominated non-radical pathway played a vital role in TC degradation. Both Co and Fe were proposed as the active sites for PMS activation, and the CoFeO@CHB/PMS system showed a high potential in practical application due to its high selectivity and robustness with much less toxic intermediate products. Furthermore, a long-term continuous home-made dead-end filtration device was constructed to evaluate the stability and application potential of the CoFeO@CHB/PMS system, in which a >70% removal was maintained in a continuous 800 min filtration. These results showed the promising potential for cellulose hydrogel beads utilized as a metal-based nanomaterial substrate for organic degradation via PMS activation. [ABSTRACT FROM AUTHOR]

Enhancing the peroxymonosulfate (PMS) activation efficiency to generate more radicals is vital to promote the Fenton‐like reaction activity, however, how to promote the PMS adsorption and accelerate the interfacial electron transfer to boost its activation kinetics remains a great challenge. Herein, we prepared Cu‐doped defect‐rich In2O3 (Cu‐In2O3/Ov) catalysts containing asymmetric Cu−Ov−In sites for PMS activation in water purification. The intrinsic catalytic activity is that the side‐on adsorption configuration of the O−O bond (Cu−O−O−In) at the Cu‐Ov‐In sites significantly stretches the O−O bond length. Meanwhile, the Cu‐Ov‐In sites increase the electron density near the Fermi energy level, promoting more and faster electron transfer to the O−O bond for generating more SO4⋅− and ⋅OH. The degradation rate constant of tetracycline achieved by Cu‐In2O3/Ov is 31.8 times faster than In2O3/Ov, and it shows the possibility of membrane reactor for practical wastewater treatment. [ABSTRACT FROM AUTHOR]

Fenton-like reaction with targeted reactive species was tested for up-cycling of waste plastics to value-added chemicals and we demonstrated a bimetal-carbon-activated peroxymonosulfate (PMS) Fenton-like system for effectively converting polypropylene into hydrocarbons and ketones. In a hydrothermal reaction process at 160 °C for 14 h, directional polypropylene conversion was achieved at a selectivity of 80 wt% hydrocarbons and ketones in the products. The distribution of Cu-Mg bimetallic sites on a carbon substrate exhibited a synergistic effect, and their catalytic activation of PMS induced specific generation of •OH-dominated reactive species. The target reactive species controlled the oxidizing capacity of the system. The efficient breaking of C-C/C-H bond in polypropylene and the subsequent further oxidation under mild conditions led to the dominated products of hydrocarbons and ketones. This study provides an attractive approach for upcycling waste plastics, thus promoting circular economy and carbon reduction. [Display omitted] • 3D wood sponge-loaded Cu-Mg catalysts were prepared by in situ growth. • Electron transfer by Cu-Mg bimetallic synergy enhanced peroxymonosulfate activation. • Polypropylene (PP) oxidation was controlled by •OH-dominant active species. • •OH drove the sequential breaking of C-C/C-H bonds in PP products oxidation. [ABSTRACT FROM AUTHOR]

Heteroatom doping represents a promising strategy for enhancing the generation of singlet oxygen (1O 2) during the activation of peroxymonosulfate (PMS) using carbon-based catalysts; however, it remains a formidable challenge. In this study, we systematically controlled the structure of metal-free carbon-based materials by introducing different heteroatoms to investigate their efficacy in degrading organic pollutants in water via PMS activation. The results of reactive oxygen species detection showed that the dominant free radical in the four samples was different: CN (•SO 4 - and •OH), CNS (•O 2 -), CNCl (1O 2), and CNClS (1O 2). This led to the transformation of active species from free radicals to non-free radicals. The tri-doped carbons with nitrogen, sulfur, and chlorine (CNClS) exhibited exceptional performance in PMS activation and achieved a remarkable degradation efficiency of 95% within just 6 min for tetracycline. Moreover, a strong linear correlation was observed between the ratio of pyridine-N/graphite-N and I D /I G with the yield of 1O 2 , indicating that N species and defects play a crucial role in CNClS as they facilitate the transition from radical to non-radical pathways during PMS activation. These findings highlight the possibility that adjustable tri-heteroatom doping will expand the Fenton-like reaction for the treatment of actual wastewater. [Display omitted] ● The structure and composition of carbon-based catalyst were modified by heteroatom doping. ● Efficient activation of peroxymonosulfate (PMS) was achieved on CNClS. ● Singlet oxygen (1O 2) plays a predominant role in the CNClS/PMS system. ● The structure-activity relationship was established with the yield of 1O 2. [ABSTRACT FROM AUTHOR]

By systematically regulating the Fe-O coordination number of feroxyhyte (δ-FeOOH), we disclosed the structure–activity relationship and developed a highly efficient Fenton-like catalyst. [Display omitted] • Coordination number of Fe atoms were regulated through tuning δ-FeOOH thickness. • 5-coordinated Fe sites accelerate the rate-limiting step and facilitate the PMS activation. • The PMS utilization efficiency achieved as high as 78.40%. • The catalytic mechanism of low coordination Fe sites were proposed. • Fe-O 5 nanosheets were assembled into laminar membrane for micropollutants treatment. Efficient purification of water is essential to remove organic micropollutants for human and environmental health. The development of catalysts with high activity and peroxymonosulfate (PMS) utilization efficiency for removal of organic micropollutants remains challenging. Inspired by natural enzymes, we designed δ-FeOOH nanosheets with abundant 5-coordinated iron sites, which are responsible for the formation of iron-peroxy (FeIII-O-O-FeIII) species with PMS. The iron-peroxy species can directly oxidize and degrade electron-rich micropollutants (e.g. BPA) with an ultra-high PMS utilization efficiency of 78.4%. A laminar membrane constructed from a stack of δ-FeOOH nanosheets, replete with an abundance of 5-coordinated iron sites. The laminar membrane can degrade multiple micropollutants by almost 100% due to nonlinear transport between the δ-FeOOH nanolayers, compared with the dispersed catalyst. This work would motivate the community to focus more on the diversified behavior of the coordination number of active centers in the design of efficient catalysts for water purification. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Corn straw-based biochar and MnFe 2 O 4 composites have been prepared. • The composites manifest excellent peroxymonosulfate-driven oxidative effect. • The dependence of catalytic activity on structure of composites is founded. • The activities of composites maintain efficient under variant factors. • The degradation mechanism including three ways is proposed. Abstract Three novel graphitized hierarchical porous biochar (MX) and MnFe 2 O 4 magnetic composites (MnFe 2 O 4 /MX) have been prepared for degrading organic pollutants by peroxymonosulfate (PMS) activation. MX including MS, ML, MC synthesized using corn stems (S), leaves (L) and cores (C) as raw materials, respectively, possesses hierarchical porous structure, graphitization domains and tremendous surface area. The orange II removal effects of MX and MnFe 2 O 4 /MX outperform the corresponding carbonization products, despite that adsorption probably undertakes the major removal efficiency for MX and degradation contributes the most for MnFe 2 O 4 /MX. A structure-dependent degradation efficiency is discovered for MX and MnFe 2 O 4 /MX, among of which both MS and MnFe 2 O 4 /MS present the best removal effect, by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The lowest EIS owning to its better balance between graphitization degree and specific surface area and micropore volume of MnFe 2 O 4 /MS among MnFe 2 O 4 /MX explains its best catalytic activity. The catalytic degradation occurs by the following three ways. First, the radical-induced oxidation is attained by surface-bound SO 4 − and OH on MnFe 2 O 4 nanoclusters and hierarchical porous carbon nanosheets generated by one-electron reduction of PMS under the participating and coupling of Mn(III)/Mn(II), Fe(III)/Fe(II), O 2 / O 2 −, and active sites on carbon surface. Second, non-radical pathway involves the contribution of 1O 2 , which is produced in a large quantity by promoted self-decomposition of PMS in presence of MnFe 2 O 4 /MS. Third, non-radical pathway is achieved through electron transfer from organic compounds as electron donator to PMS as electron acceptor mediated by graphitization structures. Taking into consideration the excellent degradation performance, easy magnetic separation, and bulk availability of MnFe 2 O 4 /MS, this work is expected to pave a new way for precision utilization of corn biomass-based biochar for environmental application. [ABSTRACT FROM AUTHOR]

• Mn-NPs loaded N-doped RGO (Mn-NRGO) was used for PMS activation to degrade BPA. • A selectivity toward different aromatic compounds in Mn-NRGO/PMS system was found. • Mn-NRGO/PMS system degraded BPA by mediated electron transfer pathway. • The electron transfer pathway was achieved by outer-sphere catalyst-PMS complex. • The crucial role of synergistic effect between Mn-NPs and doped N was elucidated. A family of graphene-based activators including reduced graphene oxide (RGO), nitrogen doped reduced graphene oxide (NRGO), zero-valent manganese loaded reduced graphene oxide (Mn-RGO) and zero-valent manganese loaded N-doped reduced graphene oxide (Mn-NRGO) were fabricated to activate peroxymonosulfate (PMS) for bisphenol A (BPA) degradation. A significant synergistic effect between loaded manganese nano-particles (Mn-NPs) and doped N was revealed by comparing the apparent reaction rate constants with about 12.4, 7.6 and 10.5-folds enhancement when compared Mn-NRGO with RGO, NRGO, Mn-RGO, respectively. By integrating the results of chemical scavenger experiment, electron paramagnetic resonance test, galvanic oxidation process, PMS stoichiometric efficiency, linear sweep voltammetry and in-situ Raman spectrum, a predominant outer-sphere catalyst-PMS complexes mediated electron transfer pathway was uncovered. Based on kinetic studies, the specific contribution of synergistic effect was quantified to be at least 70%. The calculated Fermi level advanced by 0.03 eV in Mn-NG compared with that in NG, demonstrating that Mn-NG is more liable to donate electrons to PMS. The E ads and l O-O results pointed out that synergistic effect between Mn-NPs and doped N relied on the intimate affinity between Mn-NPs and HSO 5 – which triggered more uneven distribution of charge on the whole carbon sheets, and more adsorption of HSO 5 – on carbon framework. These newly created adsorption consequently reinforcing the formation of catalyst-PMS complexes and the elevation of mediated electron transfer pathway. Overall, this study firstly provides a comprehensive and definite insight of the synergistic effect between loaded Mn-NPs and doped-N on carbon materials for promoting PMS activation to degrade organics. [ABSTRACT FROM AUTHOR]

[Display omitted] • CoP/CoO x was synthesized by a reliable partial phosphidation method. • CoP/CoO x had abundant oxygen vacancies and excellent conductivity. • CoP/CoO x showed superior catalytic activity and stability. • The synergy between abundant OVs and high CTE enhanced the PMS activation. Both introducing oxygen vacancies (OVs) and enhancing charge transfer efficiency (CTE) have been proved to be effective strategies to improve the capability of the catalyst to activate peroxymonosulfate (PMS). The OVs on catalysts can promote the CTE of the catalyst/PMS oxidation system. However, current OVs introduction methods can only lead to very limited CTE enhancement. Here, the synthesis of CoP/CoO x heterostructured nanoparticles with abundant OVs and dramatically enhanced CTE through a reliable partial phosphidation method using ZIF-67 as a precursor was reported. The excellent CTE of the CoP/CoO x /PMS oxidation system was the result of the synergy of increased OVs and introduced CoP with high conductivity. When served as Fenton-like catalyst for tetracycline (TC) degradation via activating PMS, due to the synergy between abundant OVs and high CTE, CoP/CoO x exhibited superior performance for TC removal, with the pseudo-second-order kinetic rate constant ∼ 10.3 and 77.4 times that of CoP x and Co 3 O 4 , respectively. Moreover, the cobalt leakage (0.06 mg/L) was only about 1/2 and 1/3 of that of CoP x and Co 3 O 4 , respectively. The mechanism study suggested that SO 4 •−, •OH and O 2 •− played an important role in TC degradation. The excellent catalytic performance of CoP/CoO x was attributed to its abundant OVs and high CTE to generate more active oxygen species. This work provides new insights for designing and developing efficient catalysts for wastewater treatment via Fenton-like process. [ABSTRACT FROM AUTHOR]