Enhanced Interfacial Electron Transfer by Asymmetric Cu-Ov -In Sites on In2 O3 for Efficient Peroxymonosulfate Activation

Unraveling the anti-poisoning mechanism of highly dispersed Ni atoms enhanced porous MnOx catalysts in the selective reduction of NOx by NH3

Rationally designing catalysts suitable for flue gas purification at low temperatures and unraveling the anti-poisoning mechanism at the atomic level remain challenges. Here, a highly dispersed Ni-doped MnOx catalyst (Ni0.1Mn0.9Ox) was constructed and applied for selective catalytic reduction (SCR) of nitrogen oxides (NOx). The long-term stability of Ni0.1Mn0.9Ox is up to 80% (180 °C) after 18 h under SO2 and H2O conditions. This is due to the fact that the highly dispersed Ni atoms enhance the redox and surface acidity of MnOx, and modulate the electronic structure of the active Mn sites. The denitrification reaction on Ni0.1Mn0.9Ox mainly follows the Eley-Rideal mechanism. The anti-poisoning mechanism is that the introduction of Ni weakens the electron transfer between the Mn site and SO2, thereby inhibiting the adsorption of SO2. In particular, the H2O adsorbed on the Ni sites is decomposed to replenish the depleted Brønsted acid sites, which facilitates the adsorption of NH3. However, an excess of H2O can have an inhibitory effect. In addition, the mesoporous structure may increase the mass transfer rate and reduce the accumulation of harmful substances. This study provides viable insights for the design of SCR catalysts with excellent anti-poisoning ability.

Cu doping induced asymmetric Cu-Vs-In active sites in In2S3 for efficient photocatalytic C2H4 conversion from CO2

Selective reduction of CO2 to value-added C2-chemical fuels, (such as C2H4) holds great promise for directly converting solar energy into chemical energy. However, the weak adsorption of CO2 on photocatalysts directly affects its conversion efficiency. Here we use Cu doping to create asymmetric Cu-S-vacancies-In (Cu-VS-In) sites in the two-dimensional In2S3, which greatly improves CO2 adsorption, achieving efficient photocatalytic reduction of CO2 to C2H4. Experiments and DFT (Density functional theory) calculations show that Cu doping, due to the influence of charge balance, will induce S vacancies and change the coordination environment around In atoms. This changes the mode of CO2 adsorption and decreases the adsorption energy of CO2. The asymmetric Cu-VS-In sites promote charge transfer to the CO bond, increasing catalytic activity. The concept of using asymmetric sulfur vacancies to simultaneously regulate both adsorption and charge transfer between catalysts and reactants provides a design guide for the development of advanced catalytic materials aimed at photocatalytic CO2 reduction.

Constructing zinc defects in zinc oxide and interface-anchoring of tricobalt tetraoxide: Modulating d-band center for efficient peroxymonosulfate activation

Heterojunction catalysts with defects are effective for electron transfer and peroxymonosulfate (PMS) activation. In this study, a Zn vacancy-rich ZnO/Co3O4 (Zn1-xO/Co3O4) catalyst featuring Zn-O-Co interfacial bonds was synthesized with Zn1-xO as a matrix. Its ability to activate PMS for the degradation of ciprofloxacin (CIP) was investigated. The Zn1-xO/Co3O4 achieved nearly complete CIP degradation within 20  min under 17 W sterilamp irradiation. The normalization kinetic constant was 21.7 min-1 M-1, which is 7.2 times higher than that of ZnO. Experimental results and theoretical calculations demonstrated that the Zn vacancy and Co species synergistically enhanced PMS adsorption. The incorporation of Co facilitated the desorption of adsorbed species from the Zn site by lowering the d-band center and promoted electron transfer to PMS. Sterilamp irradiation facilitated the generation of active radicals. The catalyst exhibited high CIP degradation ratios in the continuous-flow experiment, with over 90 % of CIP degraded within 180 min. This study presents a novel approach to enhance the catalytic activity of ZnO for pollutants degradation.

Leveraging Polaron Effect for Solar-Driven Efficient Peroxymonosulfate Activation in Water Purification

Peroxymonosulfate (PMS) represents a promising advanced oxidation technique for the treatment of refractory pollutants; however, its application is limited by high costs resulting from excessive usage due to low activation efficiency. In this study, we formulated a sunlight-driven Cu1-Ov/TiO2 catalyst with surface electron polaron sites to activate PMS for the degradation of contaminants, achieving a record reaction rate of k = 2.998 min-1 even with a low PMS dosage of 0.3 mM. The adsorption process and electron transfer kinetics were significantly enhanced with surface polaron sites in Cu1-Ov/TiO2, which facilitated the activation of PMS and increased the reaction rate constant k by 29.1 times compared with that of TiO2/PMS under illumination. Additionally, we verified that light irradiation promotes transfer from the non-free-radical pathway to the efficient free-radical pathway in mechanism of PMS activation. Our designed sunlight-driven flow-through PMS setup achieves a removal rate exceeding 90% for 7 days of outdoor operation at 3.2 × 102 L m-2 h-1, the feasibility of which is further proven in regions around the world by analysis of solar intensity. This study presents a demonstration of economical PMS application in water purification worldwide, with an estimated cost of 0.135 $ m-3.

Sonicated Carbon Nanotube Catalysts for Efficient Point-of-use Water Treatment

The rising demand for freshwater and increasing contamination of distributed water sources, such as stormwater and surface water, necessitate innovative point-of-use treatment technologies. Advanced oxidation processes (AOPs) using solid oxidants offer a promising approach for decentralized freshwater production but are often limited by nonselective radical reactions that degrade both pollutants and background water constituents. Here, sonicated carbon nanotubes (CNTs) that efficiently activate peroxymonosulfate are demonstrated, enabling selective contaminant degradation via dual nonradical pathways-singlet oxygen oxidation and direct electron transfer. Optimized sonication introduces catalytically active carbonyl (C═O) groups on CNT surfaces while preserving their graphitic structure, ensuring rapid electron transfer. This approach achieves 2,4-dichlorophenol removal, a common industrial and municipal pollutant, within 5 min at a record removal rate of 4.80 µmol g-1 s-1. Furthermore, scalable CNT catalyst synthesis and integration into flat membrane and hollow fiber filtration devices, ensuring long-term stability and efficient pollutant removal in natural river water, are demonstrated. By advancing selective CNT catalysts for AOPs, this work offers a scalable, sustainable solution for point-of-use freshwater production in real-world applications.

Enhancing the Reactivity of Nanozymes by Asymmetric Structural Oxygen Vacancy Electron Transfer for Colorimetric Sensing and TAC Analysis

By regulating the electron density of atoms within the reaction active center, the catalytic activity of nanozymes can be precisely controlled, thereby enhancing their reactivity and sensitivity in applications such as colorimetric sensing. In this study, we synthesized metal oxide Fe-MMOov nanozymes, enriched with doping defects and oxygen vacancy defects, by Fe-doped LDH with an ultrathin 2D structure through roasting-induced topological transformation. This process tunes the electron density distribution within the active center atoms of the nanozymes through its intrinsic asymmetric Zn-Ov-Fe doping structure, resulting in excellent POD-like and OXD-like multienzyme activities. This enhancement contributes to the overall effectiveness of nanozymes in applications such as colorimetry. These improvements facilitated its successful application in the total antioxidant capacity (TAC) detection of various fruit juices and commercial beverages. Density functional theory (DFT) calculations revealed that the d-band center of the Fe active center is enhanced by the Ov microenvironment within the Fe-MMOov nanozyme, leading to improved catalytic activity. Based on this, a Fe-MMOov/TMB visual colorimetric system was established and successfully validated for colorimetric detection of analytes such as ascorbic acid, cysteine, and glutathione. It was further integrated with a mobile platform for on-site TAC detection in food samples. This study introduces an approach for nanozyme design in colorimetric sensing while also presenting a rapid, cost-effective, and dependable strategy for the miniaturization, convenience, and widespread applicability of TAC detection. We demonstrate how the introduction of oxygen vacancies into Fe-MMOov nanozymes enhances their catalytic activity, paving the way for the development of more efficient catalysts in colorimetric detection.

In Situ Tailored Frustrated Lewis Pairs on Asymmetric Bi─Ov─In Motifs Domino-Direct High-Efficiency Urea Electrosynthesis

The green urea synthesis via co-electrolysis of waste nitrate and CO2 is alluring but challenging, especially with insufficient selectivity caused by thermodynamic differences and kinetic mismatch between multi-step conversion processes. Here, a domino effect-oriented electrosynthesis strategy is showcased to steer cascade reactions in upgrading nitrate and CO2 toward urea of high selectivity on Bi-doped In2O3 with asymmetric oxygen vacancies (Ov). The conventionally arbitrary reaction mode can be vectored and re-customized by stable and cumulative *NH2 intermediates in situ derived from priority nitrate reduction reaction, which not only form surface frustrated Lewis pairs (SFLPs, Bi─Ov─In─NH2) with Bi Lewis acid sites to synergistically adsorb and activate CO2 but also provide more opportunities for sluggish C─N coupling, delivering an unprecedented urea Faradic efficiency of 80.2% and an impressive urea yield of 2.38 × 103 µg h-1 mgcat. -1 at -0.4 V versus RHE. The atomically dispersed Bi sites promote the protonation of *NO to form nucleophilic *NH2 intermediates, which can be stabilized in the electrophilic region mediated by asymmetric Ov, permitting two nucleophilic attacks to complete the C─N coupling. The domino modeling protocol via positioning a specific intermediate in situ tailors the parallel conversion process and may guide selectivity control of electrosynthesis.

Boosting Urea Electrosynthesis via Asymmetric Oxygen Vacancies in Zn-Doped Fe2O3 Catalysts

Urea electrosynthesis from CO2 and nitrate (NO3 -) provides an attractive pathway for storing renewable electricity and substituting traditional energy-intensive urea synthesis technology. However, the kinetics mismatching between CO2 reduction and NO3 - reduction, as well as the difficulty of C─N coupling, are major challenges in urea electrosynthesis. Herein, we first calculated the free energy of *CO, *OCNO, and *NOH formation over defect-rich Fe2O3 catalysts with different metal dopants, which showed that Zn dopant was a promising candidate. Based on the theoretical study, we developed Zn-doped defect-rich Fe2O3 catalysts (Zn-Fe2O3/OV) containing asymmetric Zn-OV-Fe sites. It exhibited an outstanding urea faradaic efficiency of 62.4% and the remarkable recycling stability. The production rate of urea was as high as 7.48 mg h-1 mgcat -1, which is higher than most of the reported works to date. Detailed control experiments and in situ spectroscopy analyses identified *OCNO as a crucial intermediate for C─N coupling. The Zn-Fe2O3/OV catalyst with asymmetric Zn-OV-Fe sites showed enhanced *CO coverage and promoted *OCNO formation, leading to high efficiency toward urea production.

Unlocking One-Step Two-Electron Oxygen Reduction via Metalloid Boron-Modified Zn3In2S6 for Efficient H2O2 Photosynthesis

The indirect two-step two-electron oxygen reduction reaction (2e- ORR) dominates photocatalytic H2O2 synthesis but suffers from sluggish kinetics, •O2 --induced catalyst degradation, and spatiotemporal carrier-intermediate mismatch. Herein, we pioneer a metal-metalloid dual-site strategy to unlock the direct one-step 2e- ORR pathway, demonstrated through boron-engineered Zn3In2S6 (B-ZnInS) photocatalyst with In-B dual-active sites. The In-B dual-site configuration creates a charge-balanced electron reservoir by charge complementation, which achieves moderate O2 adsorption via bidentate coordination and dual-channel electron transfer, preventing excessive O─O bond activation. Simultaneously, boron doping induces lattice polarization to establish a built-in electric field, quintupling photogenerated carrier lifetimes versus pristine ZnInS. These synergies redirect the O2 activation pathway from indirect to direct 2e- ORR process, delivering an exceptional H2O2 production rate of 3121 µmol g-1 h-1 in pure water under simulated AM 1.5G illumination (100 mW cm-2)-an 11-fold enhancement over ZnInS. The system achieves an unprecedented apparent quantum yield of 49.8% at 365 nm for H2O2 photosynthesis among inorganic semiconducting photocatalysts, and can continuously produce medical-grade H2O2 (3 wt%). This work provides insights for designing efficient H2O2 photocatalysts and beyond.

Confining Hollow CoSn(OH)6 Cubes Inside Polydopamine Nanotubes To Significantly Promote Fenton-like Catalysis for Water Treatment

Tubular nanoreactors, which exhibit a distinctive void-confinement effect, have become intriguing for their prospective applications in catalysis. However, rationally constructing these structures remains a formidable challenge, particularly in realizing a significantly synergistic catalytic enhancement. In this study, we present a reliable template polymerization-guided synthetic strategy, creating hollow CoSn(OH)6 cubes inside polydopamine (PDA) nanotubes (CoSn(OH)6@PDA NTs). This sample functions as a potent peroxymonosulfate (PMS) activator for toxic contaminant oxidation. Diverse reactive oxygen species produced within the nanotubes significantly enhance this efficiency. The exceptional catalytic property results from the rich active sites of CoSn(OH)6 and the distinct nanotubular structure, which concentrates reactants and benefits the mass transfer process. This research opens possibilities for developing high-performance and robust catalysts with spatial confinement effects, advancing water treatment technology.

Coordination Anions Dimensionality-Engineered Dual-Atom Catalysts for Enhanced Fenton-Like Reactions: 3D Coordination Induced Spin-State Transition

Dual-atom catalysts (DACs) have shown significant application potential in Fenton-like reactions. However, effectively modulating their electronic structure and fully understanding the mechanisms driving their high catalytic activity remain challenging. Herein, we propose a coordination anions dimensionality engineering strategy to synthesize biomass-derived dual-atom FeCo-N4O1C catalysts, in which Fe and Co atoms are bridged by two-dimensional planar N atoms and a three-dimensional (3D) axial O atom. Experimental data and theoretical calculations reveal that the 3D coordination structure of FeCo-N4O1C induces the spin state of Fe undergo a transition from a low spin state to an intermediate spin state compared with single-atom Fe-N4O1C, resulting in moderate adsorption and desorption of intermediates, thus reducing the energy barriers for generating more singlet oxygen and high-valent cobalt-oxo species during peroxymonosulfate activation. The electron transfer from Co atoms to neighboring Fe atoms through N atoms and 3D axial O atoms can effectively prevent the poisoning of active species. Benefiting from the 3D coordination structure and the synergistic effects of multiple active sites, the catalyst-dose normalized reaction rate constant reaches 14.5 L min-1 g-1 under low peroxymonosulfate concentrations─an improvement of 1 ∼ 2 orders of magnitude over most reported catalysts. The practical applicability of FeCo-N4O1C is demonstrated through nearly 100% pollutant removal during 7 days of continuous operation in a membrane filtration system. This study provides deep insights into the relationship between electronic structure and catalytic performance through spin-state regulation of DACs, and introduces a promising approach for large-scale synthesis of low-cost, highly efficient DACs for Fenton-like reactions.

Homo-Hetero Double Junction Coupling Weakens Exciton Effects to Enhance Selective Photocatalytic O2 Activation on Carbon Nitride

Exciton effects caused by the inherent dielectric confinement in the 2D material carbon nitride (CN) severely limit the transfer of photogenerated carriers and the selective generation of free radicals. Herein, a homo-hetero double junction coupling strategy is reported to address these challenges. Ternary homojunction carbon nitride (HCCN) functionalized with cyano and cyanamide groups is constructed with a built-in electric field that efficiently separates the electron-hole into different structural units, thereby reducing reverse charge recombination and weakening exciton effects. The introduction of α-Fe2O3 (FO) subsequently constructs the homo-hetero double junction catalyst FO/HCCN with a built-in electric field 127 times stronger than HCCN, which promotes the directional migration of carriers after exciton dissociation and achieves ≈100% selective generation of ·O2 - from O2. These results suggest that FO/HCCN achieves 99.6% removal of tetracycline within 20 min, with a degradation rate 12 and 46 times higher than FO/CN and HCCN, respectively. In addition, the system shows excellent stability and cyclability in real-life light experiments and trace organic contaminant removal. This homo-hetero double junction coupling strategy opens up new avenues in weakening exciton effects and precisely controlling the generation of free radicals.

Engineering Heteronuclear Dual-Metal Active Sites in Ordered Macroporous Architectures for Enhanced C2H4 Production from CO2 Photoreduction

Photocatalytic C2H4 synthesis from CO2 and H2O by utilizing solar energy represents a promising sustainable process, yet its efficiency remains significantly limited. Herein, we proposed a dual-engineered strategy integrating 3D ordered macroporous (3DOM) architectures with heteronuclear dual-metal active sites to synergistically promote the photocatalytic C2H4 production. As an example, the Cu/3DOM-In2O3 photocatalyst was synthesized by in situ incorporating Cu single atoms (Cu SAs) into 3DOM In2O3 through a template-assisted pyrolysis process. The strong interaction between Cu SAs and In2O3 resulted in the formation of charge-polarized Cu─In active sites along with abundant oxygen vacancies (OVs). 3DOM architectures serving as special nanoreactors displayed significant advantages in promoting CO2 enrichment and confining key intermediates, thereby increasing *CO coverage. Meanwhile, the charge-polarized Cu─In active sites effectively mitigated electrostatic repulsion and promoted the formation of *CO + *CHO intermediates, resulting in a thermodynamically spontaneous C─C coupling step. Therefore, the Cu/3DOM-In2O3 photocatalyst exhibited robust CO2 reduction to C2H4, achieving high C2H4 evolution rates under various CO2 concentrations, including pure CO2, 10% CO2 in Ar (simulated flue gas), and 0.04% CO2 in Ar (simulated air). This work offers a novel strategy for the construction of photocatalysts with tailored microstructures and specific active sites to promote the conversion of CO2 and H2O into multicarbon products.

Co single-atom catalyst for efficient and long-acting activation of peroxymonosulfate: Formation of Co-N4 site and insight into the activation mechanism

While single-atom catalysts (SACs) have been extensively investigated as a high-atom-efficiency heterogeneous catalyst for peroxymonosulfate (PMS) oxidation reaction, the stable constructing and activation efficacy of the reaction sites remains less clarified. Herein, we employed gelatin as a N,O-bidentate ligand for Co (II) to form for a N-doped carbon precursor, while introducing NaCl as a template agent to induce the adoption of a Co-N conformation and disorganize the Co-O moiety. This approach facilitates uniform spatial isolation and atomic-level dispersion of Co atoms within the aerogel, effectively inhibiting the aggregation of Co during synthesis and enabling precise and controllable preparation of Co single-atom catalysts (SACs). As a result, the obtained SCAs/PMS system rapidly eliminated more than 99.6 % of 40 mg/L commercial dye in 10 min. Experimental and theoretical results reveal that the Co-N4 site can trigger facilitative dissociation/desorption of reaction intermediates and reduce energy barrier for SO5* and H* form, thereby redirecting the dissociation pathway from direct contiguous electron transfer to ROS-mediated degradation. Importantly, Co-N4 not only enhances the chemical adsorption and electron transfer between PMS and catalysts, but also functions as an interface electron bridge to facilitate internal electron hopping. As a beneficial effect that collectively endows the alternating of Co-N4 sites and ultimately improve the long-term catalytic stability. This study provides a comprehensive understanding of the Co-N4 sites and PMS activation mechanism in Co-SACs, shedding light on the structural-property correlation for PMS activation.

MnxCo3-xO4 spinel activates peroxymonosulfate for highly effective bisphenol A degradation with ultralow catalyst and persulfate usage

Persulfates-based advanced oxidation processes are highly efficient in degrading refractory organic contaminants in wastewater. However, their practical application is often limited by the extensive consumption of catalysts and oxidants. Therefore, constructing catalysts with abundant and efficient reaction interfaces is essential for improving the efficiency of persulfate activation. In this work, we develop a novel MnxCo3-xO4 spinel with highly exposed surface active sites by etching Mn-based precursors with Co ions. This process forms sufficient interface Co-O-Mn bonds, which effectively activate peroxymonosulfate (PMS) for bisphenol A (BPA) degradation. A clear structure-activity relationship is observed between the Co/Mn content ratio and the BPA degradation rate in the MnxCo3-xO4/PMS system. Notably, Mn0.1Co2.9O4 demonstrates superior PMS activation efficiency, achieving 100 % degradation of 10 mg/L BPA within 2 minutes with 0.05 g/L catalyst and 0.05 g/L persulfate usage. Experimental analyses combined with theoretical calculations identify the interface Co-O-Mn as the active site, which plays a crucial role in accelerating PMS molecule adsorption and O-O bond activation. Additionally, the spatially adjacent Co-O-Mn sites promote redox cycling for efficient interface electron transfer during the PMS activation process. Furthermore, Zebrafish toxicity studies revealed a considerable reduction in the toxicity of the BPA treatment residue in the MnxCo3-xO4/PMS system. Overall, this work presents a novel strategy for constructing spatially adjacent redox sites in dual-metal spinel materials, offering valuable insights into reducing chemical input and advancing persulfate-based environmental remediation technology.

Stabilizing the Fe Species of Nickel-Iron Double Hydroxide via Chelating Asymmetric Aldehyde-Containing THB Ligand for Long-Lasting Water Oxidation

Nickel-iron layered double hydroxides (NiFe LDHs) are considered as promising substitutes for precious metals in oxygen evolution reaction (OER). However, most of the reported NiFe LDHs suffer from poor long-term stability because of the Fe loss during OER resulting in severe inactivation. Herein, a dynamically stable chelating interface through in situ transformation of asymmetric aldehyde-ligand (THB, 1,3,5-Tris(3'-hydroxy-4'-formylphenyl)-benzene) modified NiFe LDHs to anchor Fe and significantly enhance the OER stability is reported. The fabricated asymmetric aldehyde-containing ligand THB is capable of stimulating much more interfacial charge transfer from NiFe LDHs to the oxygen group of THB and accelerating the formation of highly valent active Fe species leading to the strong combination between Fe and ligand and the reduced activation energy barrier of the intermediate, respectively. The optimized aldehyde-ligand-chelated NiFe LDHs (NiFe LDH/THB) shows enhanced OER performance featuring an overpotential of 224 mV at 100 mA cm-2 and robust stability for over 3860 h at 100 mA cm-2 in a water splitting device maintaining a cell voltage of only 1.68 V, which paves a new avenue to improve the water electrolysis performance of non-noble metal catalysts.

Calcium single atoms stabilized by nitrogen coordination in metal-organic frameworks as efficient solid base catalysts

Considerable attention has been paid to the preparation of single-atom solid base catalysts (SASBCs) owing to their high activity and maximized utilization of basic sites. At present, the reported fabrication methods of SASBCs, such as two-step reduction strategy and sublimation capture strategy, require high temperature. Such a high activation temperature is easy to cause the sublimation loss of alkali or alkaline earth metal atoms and destructive to the support structure. Herein, a new SASBC, Ca1/UiO-67-BPY, is fabricated, in which the alkaline earth metal Ca sites are immobilized onto N-rich metal-organic framework UiO-67-BPY at room temperature. The results show that the atomic configuration of Ca single atoms is coordinated by two N atoms in the framework. The obtained Ca SASBC possesses ordered structure and exhibits high product yield of 87.2% in the Knoevenagel reaction between benzaldehyde and malononitrile. Furthermore, thanks to the Ca single atoms sites anchored on UiO-67-BPY, the Ca1/UiO-67-BPY catalyst also shows good stability during cycles. This work might offer new insight in designing SASBCs for different base-catalyzed reactions.

Low-peroxide-consumption fenton-like systems: The future of advanced oxidation processes

Conventional heterogeneous Fenton-like systems employing different peroxides have been developed for water/wastewater remediation. However, a large population of peroxides consumed during various Fenton-like systems with low utilization efficiency and associated secondary contamination have become the bottlenecks for their actual applications. Recent strategies for lowering the peroxide consumptions to develop economic Fenton-like systems are primarily devoted to the effective radical generation and subsequent high-efficiency radical utilization through catalysts/systems engineering, leveraging emerging nonradical oxidation pathways with higher selectivity and longer life of the reactive intermediate, as well as reactor designs for promoting the mass transfer and peroxides decomposition to improve the yield of radicals/nonradicals. However, a comparative review summarizing the mechanisms and pathways of these strategies has not yet been published. In this review, we endeavor to showcase the designated systems achieving the reduction of peroxides while ensuring high catalytic activity from the perspective of the above strategic mechanisms. An in-depth understanding of these aspects will help elucidate the key mechanisms for achieving economic peroxide consumption. Finally, the existing problems of these strategies are put forward, and new ideas and research directions for lowering peroxide consumption are proposed to promote the application of various Fenton-like systems in actual wastewater purification.

Bismuth-based photocatalysts for pollutant degradation and bacterial disinfection in sewage system: Classification, modification and mechanism

The discharge of polluted water poses a great threat to human health. Therefore, the development of effective sewage treatment technology is a key to achieve sustainable health development of society. Recent research showed that light-driven bismuth-based nanomaterials provided a promising chance for treating sewage system owing to their adjustable electronic features, excellent physical and chemical properties, abundant storage and environmental safety. However, the detailed overview and systematic understanding of the development of highly efficient bismuth-based photocatalysts is still unsatisfactory. In this review, we summarized the classification of bismuth-based photocatalysts, and the relationship between the structural design and the change of optical performance is illustrated. Importantly, the reliable modification strategies for improving photocatalytic capability are emphasized. Finally, the challenges and future development directions of light-driven bismuth-based nanoplatforms in wastewater treatment applications are discussed, hoping to provide an effective guidance for exploring the photocatalytic wastewater treatment process.

Sabatier Principle-Driven Single-Atom Coordination Engineering for Enhanced Fenton-Like Catalysis

Single-atom catalysts (SACs) are widely employed in Fenton-like catalysis, yet guidelines for their high-performance design remain elusive. The Sabatier principle provides guidance for the ideal catalyst with the highest activity. Herein, the study meticulously engineered a series of SACs featuring a broad distribution of d-band center through single-atom coordination engineering, facilitating a comprehensive exploration of the Sabatier relationship in Fenton-like catalysis. A volcanic correlation between d-band centers and catalytic activity is identified. Theoretical and experimental results show that moderate d-band center and peroxymonosulfate adsorption energy can lead to the lowest reaction barriers in the rate-determining step for generating singlet oxygen, thus enhancing catalytic efficiency toward the Sabatier optimum. As proof of concept, the Fe-N2O2/C catalyst demonstrates a degradation rate constant of 1.89 min-1, surpassing Fe-N4/C by 3.2 times and Fe-O4/C by 272 times. Moreover, Fe-N2O2/C shows exceptional tolerance to various environmental challenges, providing opportunities for achieving nearly eco-friendly pollutant degradation. The findings reveal how to use the Sabatier principle to guide the design of advanced SACs for efficient pollutant removal.

Endogenous Substances Utilization for Water Self-Purification Amplification Driven by Nonexpendable H2O2 over a Micro-Potential Difference Surface

Natural self-purification of water is limited by mass transfer processes between inert oxygen (O2) and stable pollutants. This process must rely on large energy inputs and resource consumption, which have become a global challenge in the environmental field. Here, we greatly amplify this self-purification effect of natural dissolved oxygen (DO) by nonexpendable H2O2 triggering a DRC catalyst with a micro-potential difference surface. This low-energy strategy is mainly realized by lowering the activation energy barriers of endogenous substances and simultaneously opening the mass transfer channels over the Cu-ZnO surface. In this way, pollutant electrons and energy are efficiently utilized to activate DO. Surprisingly, the rapid degradation of the pollutants is accompanied by H2O2 consumption of only 2.6% at most, sometimes even reaching zero consumption, with the instantaneous absolute amount of H2O2 exceeding 100%. The typical endocrine disruptor BPA has been proven to be harmlessly degraded to small molecule alcohols and acids by self-purification amplification, including cleavage of stable contaminants on the catalyst surface, activation of natural DO, and enhancement of mass transfer between them.

Irreversible Lattice Expansion Effects in Nanoscale Indium Oxide for CO2 Hydrogenation Catalysis

Thermal energy has been considered the exclusive driving force in thermochemical catalysis, yet associated lattice expansion effects have been overlooked. To shed new light on this issue, variable temperature in situ high-resolution (scanning) transmission electron microscopy (HR-(S)TEM) and electron energy-loss spectroscopy (EELS) were employed to provide detailed information on the structural changes of an archetype nanoscale indium oxide materials and how these effects are manifest in reverse water gas shift heterogeneous catalytic reactivity. It is found that with increasing temperature and vacuum conditions, an irreversible surface lattice expansion is traced to the formation and migration of oxygen vacancies. Together, these changes are believed to be responsible for the decreased activation energy and improved reaction rate observed for the reverse water gas shift reaction. Studies of this kind provide new insight into how thermal energy affects thermochemical heterogeneous catalysis.

Unraveling the Fundamentals of Axial Coordination FeN4+1 Sites Regulating the Peroxymonosulfate Activation for Fenton-Like Activity

Precise modulation of the axial coordination microenvironment in single-atom catalysts (SACs) to enhance peroxymonosulfate (PMS) activation represents a promising yet underexplored approach. This study introduces a pyrolysis-free strategy to fabricate SACs with well-defined axial-FeN4+1 coordination structures. By incorporating additional out-of-plane axial nitrogen into well-defined FeN4 active sites within a planar, fully conjugated polyphthalocyanine framework, FeN4+1 configurations are developed that significantly enhance PMS activation. The axial-FeN4+1 catalyst excelled in activating PMS, with a high bisphenol A (BPA) degradation rate of 2.256 min-1, surpassing planar-FeN4/PMS systems by 6.8 times. Theoretical calculations revealed that the axial coordination between N and the Fe sites forms an optimized axial FeN4+1 structure, disrupting the electron distribution symmetry of Fe and optimizing the electron distribution of the Fe 3d orbital (increasing the d-band center from -1.231 to -0.432 eV). Consequently, this led to an enhanced perpendicular adsorption energy of PMS from -1.79 to -1.82 eV and reduced energy barriers for the formation of the key reaction intermediate (O*) that generates 1O2. This study provides new insights into PMS activation through the axial coordinated engineering of well-defined SACs in water purification processes.

Fundamental Insights into the Direct Electron Transfer Mechanism on Ag Atomic Cluster

The nonradical oxidation pathway for pollutant degradation in Fenton-like catalysis is favorable for water treatment due to the high reaction rate and superior environmental robustness. However, precise regulation of such reactions is still restricted by our poor knowledge of underlying mechanisms, especially the correlation between metal site conformation of metal atom clusters and pollutant degradation behaviors. Herein, we investigated the electron transfer and pollutant oxidation mechanisms of atomic-level exposed Ag atom clusters (AgAC) loaded on specifically crafted nitrogen-doped porous carbon (NPC). The AgAC triggered a direct electron transfer (DET) between the terminal oxygen (Oα) of surface-activated peroxodisulfate and the electron-donating substituents-containing contaminants (EDTO-DET), rendering it 11-38 times higher degradation rate than the reported carbon-supported metal catalysts system with various single-atom active centers. Heterocyclic substituents and electron-donating groups were more conducive to degradation via the EDTO-DET system, while contaminants with high electron-absorbing capacity preferred the radical pathway. Notably, the system achieved 79.5% chemical oxygen demand (COD) removal for the treatment of actual pharmaceutical wastewater containing 1053 mg/L COD within 30 min. Our study provides valuable new insights into the Fenton-like reactions of metal atom cluster catalysts and lays an important basis for revolutionizing advanced oxidation water purification technologies.

Efficient solar-driven freshwater generation through an inner hierarchical porous metal-carbon layer bridging synergistic photothermal evaporation and adsorption photodegradation

Solar-driven interfacial evaporation has emerged as a promising avenue for clean water production, leveraging solar energy to extract water vapor from salty and polluted water sources. However, a critical challenge remains, during the photothermal evaporation process, organic pollutants and small water-soluble molecules can transfer into distilled steam, degrading the purity of the collected water. Herein, we develop a multifunctional clean water generation system that integrates photothermal conversion, adsorptive filtration and subsequent photocatalytic purification within a unified platform. This system features an inner hierarchical porous metal-carbon layer derived from ZIF-67 carbonization, seamlessly bridging a wood carbon scaffold and BiOBr nanosheets (BiOBr@ZCW) to smoothly facilitate synergistic actions between photothermal evaporation and adsorption-photodegradation processes. This BiOBr@ZCW configuration not only minimizes thermal dissipation, facilitating a high evaporation rate of 1.67 kg m-2 h-1 and an efficiency of 85% under standard solar irradiation but also enhances the photocatalytic degradation of the rhodamine B organic pollutant with a remarkable 98.43% degradation rate within just 20 minutes. This integrated system offers a robust solution to the challenges of water purification by ensuring both high efficiency in solar steam generation and effective pollutant degradation.

Atomically Dispersed Cobalt Anchored on Hollow Tubular Carbon Nitride Mediates Direct Electron Transfer and Oxygen-Related Active Species Path for Activation of Permonosulfate

Atomically dispersed catalysts anchored on nitrogen-rich substrates present promising application potential for the persulfate-based advanced oxidation process. Nevertheless, efficient activation efficiency and a clear activated mechanism of persulfate remain challenging in carbon nitride-based single-atom catalysts (SACs). To these, combined with the regulation strategy of metal-ligand section and carrier's architecture, an atomically dispersed Co single-atom catalyst anchored on regular hollow tubular carbon nitride (Co/TCN SAC) herein was devised and utilized to activate permonosulfate. As a result, Co/TCN SACs show excellent catalytic performance for the degradation of common antibiotics. Combined with X-ray absorption fine structure and theory calculation, it is confirmed that superficially anchored CoO3 sites of the Co2N2O2-CoO3 unit are the catalytic active center for peroxymonosulfate (PMS) activation. The electrochemical test and in situ electron paramagnetic resonance results demonstrate radical (SO4•- and •OH) and nonradical (electron transfer process and 1O2) paths contributing to the superior catalytic performance. In addition, the catalyst exhibits high reaction efficiency and structural stability considering water quality parameters. Finally, a continuous and efficient device was operated on a laboratory scale, which exhibited satisfactory efficiency in continuously removing electron-rich antibiotics such as tetracycline. This work reveals the atomic-level modulation of cobalt atomic sites on hollow tubular carbon nitride and their structure-activity relationship with persulfate activation.

Remarkable Active Site Utilization in Edge-Hosted-N Doped Carbocatalysts for Fenton-Like Reaction

Improving the utilization of active sites in carbon catalysts is significant for various catalytic reactions, but still challenging, mainly due to the lack of strategies for controllable introduction of active dopants. Herein, a novel "Ar plasma etching-NH3 annealing" strategy is developed to regulate the position of active N sites, while maintaining the same nitrogen species and contents. Theoretical and experimental results reveal that the edge-hosted-N doped carbon nanotubes (E-N-CNT), with only 0.29 at.% N content, show great affinity to peroxymonosulfate (PMS), and exhibit excellent Fenton-like activity by generating singlet oxygen (1O2), which can reach as high as 410 times higher than the pristine CNT. The remarkable utilization of edge-hosted nitrogen atom is further verified by the edge-hosted-N enriched carbocatalyst, which shows superior capability for 4-chlorophenol degradation with a turnover frequency (TOF) value as high as 3.82 min-1, and the impressive TOF value can even surpass those of single-atom catalysts. This work proposes a controllable position regulation of active sites to improve atom utilization, which provides a new insight into the design of excellent Fenton-like catalysts with remarkable atom utilization efficiency.

Optimal Oxophilicity at the Fe-Nx Interface Enhances the Generation of Singlet Oxygen for Efficient Fenton-Like Catalysis

In the pursuit of efficient singlet oxygen generation in Fenton-like catalysis, the utilization of single-atom catalysts (SACs) emerges as a highly desired strategy. Here, a discovery is reported that the single-atom Fe coordinated with five N-atoms on N-doped porous carbon, denoted as Fe-N5/NC, outperform its counterparts, those coordinated with four (Fe-N4/NC) or six N-atoms (Fe-N6/NC), as well as state-of-the-art SACs comprising other transition metals. Thus, Fe-N5/NC exhibits exceptional efficacy in activating peroxymonosulfate for the degradation of organic pollutants. The coordination number of N-atoms can be readily adjusted by pyrolysis of pre-assembly structures consisting of Fe3+ and various isomers of phenylenediamine. Fe-N5/NC displayed outstanding tolerance to environmental disturbances and minimal iron leaching when incorporated into a membrane reactor. A mechanistic study reveals that the axial ligand N reduces the contribution of Fe-3d orbitals in LUMO and increases the LUMO energy of Fe-N5/NC. This, in turn, reduces the oxophilicity of the Fe center, promoting the reactivity of *OO intermediate-a pivotal step for yielding singlet oxygen and the rate-determining step. These findings unveil the significance of manipulating the oxophilicity of metal atoms in single-atom catalysis and highlight the potential to augment Fenton-like catalysis performance using Fe-SACs.

Deciphering the Novel Picolinate-Mn(II)/peroxymonosulfate System for Sustainable Fenton-like Oxidation: Dominance of the Picolinate-Mn(IV)-peroxymonosulfate Complex

A highly efficient and sustainable water treatment system was developed herein by combining Mn(II), peroxymonosulfate (PMS), and biodegradable picolinic acid (PICA). The micropollutant elimination process underwent two phases: an initial slow degradation phase (0-10 min) followed by a rapid phase (10-20 min). Multiple evidence demonstrated that a PICA-Mn(IV) complex (PICA-Mn(IV)*) was generated, acting as a conductive bridge facilitating the electron transfer between PMS and micropollutants. Quantum chemical calculations revealed that PMS readily oxidized the PICA-Mn(II)* to PICA-Mn(IV)*. This intermediate then complexed with PMS to produce PICA-Mn(IV)-PMS*, elongating the O-O bond of PMS and increasing its oxidation capacity. The primary transformation mechanisms of typical micropollutants mediated by PICA-Mn(IV)-PMS* include oxidation, ring-opening, bond cleavage, and epoxidation reactions. The toxicity assessment results showed that most products were less toxic than the parent compounds. Moreover, the Mn(II)/PICA/PMS system showed resilience to water matrices and high efficiency in real water environments. Notably, PICA-Mn(IV)* exhibited greater stability and a longer lifespan than traditional reactive oxygen species, enabling repeated utilization. Overall, this study developed an innovative, sustainable, and selective oxidation system, i.e., Mn(II)/PICA/PMS, for rapid water decontamination, highlighting the critical role of in situ generated Mn(IV).

Atomically Dispersed Cu on In2O3 for Relay Electrocatalytic Conversion of Nitrate and CO2 to Urea

Urea electrosynthesis from coelectrolysis of NO3- and CO2 (UENC) holds a significant prospect to achieve efficient and sustainable urea production. Herein, atomically dispersed Cu on In2O3 (Cu1/In2O3) is designed as an effective and robust catalyst for the UENC. Combined theoretical calculations and in situ spectroscopic analysis reveal the synergistic effect of the Cu1-O2-In site and the In site to boost the UENC energetics via a relay catalysis pathway, where the Cu1-O2-In site drives *NO3 → *NH2 and the In site catalyzes *CO2 → *CO. The generated *CO is then migrated from the In site to the Cu1-O2-In site, followed by C-N coupling with *NH2 on the Cu1-O2-In site to generate urea. Consequently, Cu1/In2O3 assembled within a flow cell exhibits an impressive urea yield rate of 28.97 mmol h-1 g-1 with a urea-Faradaic efficiency (FEurea) of 50.88%.

Long-range interactions driving neighboring Fe-N4 sites in Fenton-like reactions for sustainable water decontamination

Actualizing efficient and sustainable environmental catalysis is essential in global water pollution control. The single-atom Fenton-like process, as a promising technique, suffers from reducing potential environmental impacts of single-atom catalysts (SACs) synthesis and modulating functionalized species beyond the first coordination shell. Herein, we devised a high-performance SAC possessing impressive Fenton-like reactivity and extended stability by constructing abundant intrinsic topological defects within carbon planes anchored with Fe-N4 sites. Coupling atomic Fe-N4 moieties and adjacent intrinsic defects provides potent synergistic interaction. Density functional theory calculations reveal that the intrinsic defects optimize the d-band electronic structure of neighboring Fe centers through long-range interactions, consequently boosting the intrinsic activity of Fe-N4 sites. Life cycle assessment and long-term steady operation at the device level indicate promising industrial-scale treatment capability for actual wastewater. This work emphasizes the feasibility of synergistic defect engineering for refining single-atom Fenton-like chemistry and inspires rational materials design toward sustainable environmental remediation.

Constructing High-Performance Cobalt-Based Environmental Catalysts from Spent Lithium-Ion Batteries: Unveiling Overlooked Roles of Copper and Aluminum from Current Collectors

Converting spent lithium-ion batteries (LIBs) cathode materials into environmental catalysts has drawn more and more attention. Herein, we fabricated a Co3O4-based catalyst from spent LiCoO2 LIBs (Co3O4-LIBs) and found that the role of Al and Cu from current collectors on its performance is nonnegligible. The density functional theory calculations confirmed that the doping of Al and/or Cu upshifts the d-band center of Co. A Fenton-like reaction based on peroxymonosulfate (PMS) activation was adopted to evaluate its activity. Interestingly, Al doping strengthened chemisorption for PMS (from -2.615 eV to -2.623 eV) and shortened Co-O bond length (from 2.540 Å to 2.344 Å) between them, whereas Cu doping reduced interfacial charge-transfer resistance (from 28.347 kΩ to 6.689 kΩ) excepting for the enhancement of the above characteristics. As expected, the degradation activity toward bisphenol A of Co3O4-LIBs (0.523 min-1) was superior to that of Co3O4 prepared from commercial CoC2O4 (0.287 min-1). Simultaneously, the reasons for improved activity were further verified by comparing activity with catalysts doped Al and/or Cu into Co3O4. This work reveals the role of elements from current collectors on the performance of functional materials from spent LIBs, which is beneficial to the sustainable utilization of spent LIBs.

Anchored Cobalt Nanoparticles on Layered Perovskites for Rapid Peroxymonosulfate Activation in Antibiotic Degradation

In the Fenton-like reaction, revealing the dynamic evolution of the active sites is crucial to achieve the activity improvement and stability of the catalyst. This study reports a perovskite oxide in which atomic (Co0) in situ embedded exsolution occurs during the high-temperature phase transition. This unique anchoring strategy significantly improves the Co3+/Co2+ cycling efficiency at the interface and inhibits metal leaching during peroxymonosulfate (PMS) activation. The Co@L-PBMC catalyst exhibits superior PMS activation ability and could achieve 99% degradation of tetracycline within 5 min. The combination of experimental characterization and density functional theory (DFT) calculations elucidates that the electron-deficient oxygen vacancy accepts an electron from the Co 3d-orbital, resulting in a significant electron delocalization of the Co site, thereby facilitating the adsorption of the *HSO5/*OH intermediate onto the "metal-VO bridge" structure. This work provides insights into the PMS activation mechanism at the atomic level, which will guide the rational design of next-generation catalysts for environmental remediation.

Construction of Co-Se-W at Interfaces of Phase-Mixed Cobalt Selenide via Spontaneous Phase Transition for Platinum-Like Hydrogen Evolution Activity and Long-Term Durability in Alkaline and Acidic Media

Cost-effective transition metal chalcogenides are highly promising electrocatalysts for both alkaline and acidic hydrogen evolution reactions (HER). However, unsatisfactory HER kinetics and stability have severely hindered their applications in industrial water electrolysis. Herein, a nanoflowers-shaped W-doped cubic/orthorhombic phase-mixed CoSe2 catalyst ((c/o)-CoSe2-W) is reported. The W doping induces spontaneous phase transition from stable phase cubic CoSe2 (c-CoSe2) to metastable phase orthorhombic CoSe2, which not only enables precise regulation of the ratio of two phases but also realizes W doping at the interfaces of two phases. The (c/o)-CoSe2-W catalyst exhibits a Pt-like HER activity in both alkaline and acidic media, with record-low HER overpotentials of 29.8 mV (alkaline) and 35.9 mV (acidic) at 10 mA cm-2, respectively, surpassing the vast majority of previously reported non-precious metal electrocatalysts for both alkaline and acidic HER. The Pt-like HER activities originate from the formation of Co-Se-W active species on the c-CoSe2 side at the phase interface, which effectively modulates electron structures of active sites, not only enhancing H2O adsorption and dissociation at Co sites but also optimizing H* adsorption to ΔGH* ≈ 0 at W sites. Benefiting from the abundant phase interfaces, the catalyst also displays outstanding long-term durability in both acidic and alkaline media.

Interfacial bonding of Co3O4 and oxygen vacancies engineering on ZnO induced efficient peroxymonosulfate activation and pollutants degradation

A heterojunction of trace Co3O4 bonded on oxygen vacancies (OVs)-rich ZnO (OVs-ZnO/Co3O4) was synthesized via defect-assisted method to promote peroxymonosulfate (PMS) activation and pollutants degradation. Experiments and theoretical calculations demonstrated that electrons could efficiently transfer from OVs-ZnO to Co3O4. OVs-ZnO and Co3O4 played different roles in activating PMS. PMS was easily adsorbed on the OVs-ZnO to form PMS* complex and mediated electron transfer to oxide ciprofloxacin (CIP), whereas, Co3O4 facilitated breakup of peroxide bond to produce radicals. The optimal OVs-ZnO/Co3O4 with Co content of 1.34% exhibited good PMS decomposition ability (94.2% in 30 min) compared to unmodified ZnO (24.2%), stability and anti-interference feature in removing CIP, 96.9% CIP (10 ppm) and 79.6% of total organic carbon were removed in 30 min. Moreover, the OVs-ZnO/Co3O4 achieved 91.2% CIP removal ratio with 1.0 mM PMS via a flow-through device in 180 min. This study proposes a new strategy to enhance PMS activation of ZnO and provides new viewpoint in PMS activation way.

Co single atom coupled oxygen vacancy on W18O49 nanowires surface to construct asymmetric active site enhanced peroxymonosulfate activation

Enhancing the activation of peroxymonosulfate (PMS) is essential for generating more reactive oxygen species in advanced oxidation process (AOPs). Nevertheless, improving PMS adsorption and expediting interfacial electron transfer to enhance reaction kinetics pose significant challenges. Herein, we construct confined W18O49 nanowires with asymmetric active centers containing Co-Vo-W (Vo: oxygen vacancy). The design incorporates surface-rich Vo and single-atom Co, and the resulting material is employed for PMS activation in water purification. By coupling unsaturated coordinated electrons in Vo with low-valence Co single atoms to construct an the "electron fountainhead", the adsorption and activation of PMS are enhanced. This results in the generation of more active free radicals (SO4•-, •OH, •O2-) and non-free radicals (1O2) for the decomposition of micropollutants. Thereinto, the degradation rate of bisphenol A (BPA) by Co-W18O49 is 32.6 times faster that of W18O49 monomer, which is also much higher than those of other transition-metal-doped W18O49 composites. This work is expected to help to elucidate the rational design and efficient PMS activation of catalysts with asymmetric active centers.

The "4 + 1" strategy fabrication of iron single-atom catalysts with selective high-valent iron-oxo species generation

Single-atom catalysts (SACs) with atomic dispersion active sites have exhibited huge potentials in peroxymonosulfate (PMS)-based Fenton-like chemistry in water purification. However, four-N coordination metal (MN4) moieties often suffer from such problems as low selectivity and narrow workable pH. How to construct SACs in a controllable strategy with optimized electronic structures is of great challenge. Herein, an innovative strategy (i.e., the "4 + 1" fabrication) was devised to precisely modulate the first-shell coordinated microenvironment of FeN4 SAC using an additional N (SA-FeN5). This leads to almost 100% selective formation of high-valent iron-oxo [Fe(IV)═O] (steady-state concentration: 2.00 × 10-8 M) in the SA-FeN5/PMS system. In-depth theoretical calculations unveil that FeN5 configuration optimizes the electron distribution of monatomic Fe sites, which thus fosters PMS adsorption and reduces the energy barrier for Fe(IV)═O generation. SA-FeN5 was then attached to polyvinylidene difluoride membrane for a continuous flow device, showing long-term abatement of the microcontaminant. This work furnishes a general strategy for effective PMS activation and selective high-valent metal-oxo species generation by high N-coordination number regulation in SACs, which would provide guidance in the rational design of superior environmental catalysts for water purification.

Molecular level removal of antibiotic resistant bacteria and genes: A review of interfacial chemical in advanced oxidation processes

As a kind of novel and persistent environmental pollutants, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been frequently detected in different aquatic environment, posing potential risks to public health and ecosystems, resulting in a biosecurity issue that cannot be ignored. Therefore, in order to control the spread of antibiotic resistance in the environment, advanced oxidation technology (such as Fenton-like, photocatalysis, electrocatalysis) has become an effective weapon for inactivating and eliminating ARB and ARGs. However, in the process of advanced oxidation technology, studying and regulating catalytic active sites at the molecular level and studying the adsorption and surface oxidation reactions between catalysts and ARGs can achieve in-depth exploration of the mechanism of ARGs removal. This review systematically reveals the catalytic sites and related mechanisms of catalytic antagonistic genes in different advanced oxidation processes (AOPs) systems. We also summarize the removal mechanism of ARGs and how to reduce the spread of ARGs in the environment through combining a variety of characterization methods. Importantly, the potential of various catalysts for removing ARGs in practical applications has also been recognized, providing a promising approach for the deep purification of wastewater treatment plants.

Iron 3D-Orbital Configuration Dependent Electron Transfer for Efficient Fenton-Like Catalysis

Transition metals are excellent active sites to activate peroxymonosulfate (PMS) for water treatment, but the favorable electronic structures governing  reaction mechanism still remain elusive. Herein, the authors construct typical d-orbital configurations on iron octahedral (FeOh ) and tetrahedral (FeTd ) sites in spinel ZnFe2 O4 and FeAl2 O4 , respectively. ZnFe2 O4 (136.58 min-1 F-1 cm2 ) presented higher specific activity than FeAl2 O4 (97.47 min-1 F-1 cm2 ) for tetracycline removal by PMS activation. Considering orbital features of charge amount, spin state, and orbital arrangement by magnetic spectroscopic analysis, ZnFe2 O4 has a larger bond order to decompose PMS. Using this descriptor, high-spin FeOh is assumed to activate PMS mainly to produce nonradical reactive oxygen species (ROS) while high-spin FeTd prefers to induce radical species. This hypothesis is confirmed by the selective predominant ROS of 1 O2 on ZnFe2 O4 and O2 •- on FeAl2 O4 via quenching experiments. Electrochemical determinations reveal that FeOh has superior capability than FeTd for feasible valence transformation of iron cations and fast interfacial electron transfer. DFT calculations further suggest octahedral d-orbital configuration of ZnFe2 O4 is beneficial to enhancing Fe-O covalence for electron exchange. This work attempts to understand the d-orbital configuration-dependent PMS activation to design efficient catalysts.

Efficient Removal of Antibiotic Resistance Genes through 4f-2p-3d Gradient Orbital Coupling Mediated Fenton-Like Redox Processes

Peroxymonosulfate (PMS) mediated radical and nonradical active substances can synergistically achieve the efficient elimination of antibiotic resistance genes (ARGs). However, enhancing interface electron cycling and optimizing the coupling of the oxygen-containing intermediates to improve PMS activation kinetics remains a major challenge. Here, Co doped CeVO4 catalyst (Co-CVO) with asymmetric sites was constructed based on Ce 4f-O 2p-Co 3d gradient orbital coupling. The catalyst achieved approximately 2.51×105 copies/mL of extracellular ARGs (eARGs) removal within 15 minutes, exhibited ultrahigh degradation rate (k=1.24 min-1 ). The effective gradient 4f-2p-3d orbital coupling precisely regulates the electron distribution of Ce-O-Co active center microenvironment, while optimizing the electronic structure of Co 3d states (especially the occupancy of eg ), promoting the adsorption of oxygen-containing intermediates. The generated radical and nonradical generated by interfacial electron cycling enhanced by the reduction reaction of PMS at the Ce site and the oxidation reaction at the Co site achieved a significant mineralization rate of ARGs (83.4 %). The efficient removal of ARGs by a continuous flow reactor for 10 hours significantly reduces the ecological risk of ARGs in actual wastewater treatment.

Self-carbon-thermal-reduction strategy for boosting the Fenton-like activity of single Fe-N4 sites by carbon-defect engineering

Carbon-defect engineering in metal single-atom catalysts by simple and robust strategy, boosting their catalytic activity, and revealing the carbon defect-catalytic activity relationship are meaningful but challenging. Herein, we report a facile self-carbon-thermal-reduction strategy for carbon-defect engineering of single Fe-N4 sites in ZnO-Carbon nano-reactor, as efficient catalyst in Fenton-like reaction for degradation of phenol. The carbon vacancies are easily constructed adjacent to single Fe-N4 sites during synthesis, facilitating the formation of C-O bonding and lowering the energy barrier of rate-determining-step during degradation of phenol. Consequently, the catalyst Fe-NCv-900 with carbon vacancies exhibits a much improved activity than the Fe-NC-900 without abundant carbon vacancies, with 13.5 times improvement in the first-order rate constant of phenol degradation. The Fe-NCv-900 shows high activity (97% removal ratio of phenol in only 5 min), good recyclability and the wide-ranging pH universality (pH range 3-9). This work not only provides a rational strategy for improving the Fenton-like activity of metal single-atom catalysts, but also deepens the fundamental understanding on how periphery carbon environment affects the property and performance of metal-N4 sites.

Facilely Tuning the First-Shell Coordination Microenvironment in Iron Single-Atom for Fenton-like Chemistry toward Highly Efficient Wastewater Purification

Precisely identifying the atomic structures in single-atom sites and establishing authentic structure-activity relationships for single-atom catalyst (SAC) coordination are significant challenges. Here, theoretical calculations first predicted the underlying catalytic activity of Fe-NxC4-x sites with diverse first-shell coordination environments. Substituting N with C to coordinate with the central Fe atom induces an inferior Fenton-like catalytic efficiency. Then, Fe-SACs carrying three configurations (Fe-N2C2, Fe-N3C1, and Fe-N4) fabricate facilely and demonstrate that optimized coordination environments of Fe-NxC4-x significantly promote the Fenton-like catalytic activity. Specifically, the reaction rate constant increases from 0.064 to 0.318 min-1 as the coordination number of Fe-N increases from 2 to 4, slightly influencing the nonradical reaction mechanism dominated by 1O2. In-depth theoretical calculations unveil that the modulated coordination environments of Fe-SACs from Fe-N2C2 to Fe-N4 optimize the d-band electronic structures and regulate the binding strength of peroxymonosulfate on Fe-NxC4-x sites, resulting in a reduced energy barrier and enhanced Fenton-like catalytic activity. The catalytic stability and the actual hospital sewage treatment capacity also showed strong coordination dependency. This strategy of local coordination engineering offers a vivid example of modulating SACs with well-regulated coordination environments, ultimately maximizing their catalytic efficiency.

Single cobalt atoms anchored on Ti3C2Tx with dual reaction sites for efficient adsorption-degradation of antibiotic resistance genes

The assimilation of antibiotic resistance genes (ARGs) by pathogenic bacteria poses a severe threat to public health. Here, we reported a dual-reaction-site-modified CoSA/Ti3C2Tx (single cobalt atoms immobilized on Ti3C2Tx MXene) for effectively deactivating extracellular ARGs via peroxymonosulfate (PMS) activation. The enhanced removal of ARGs was attributed to the synergistic effect of adsorption (Ti sites) and degradation (Co-O3 sites). The Ti sites on CoSA/Ti3C2Tx nanosheets bound with PO43- on the phosphate skeletons of ARGs via Ti-O-P coordination interactions, achieving excellent adsorption capacity (10.21 × 1010 copies mg-1) for tetA, and the Co-O3 sites activated PMS into surface-bond hydroxyl radicals (•OHsurface), which can quickly attack the backbones and bases of the adsorbed ARGs, resulting in the efficient in situ degradation of ARGs into inactive small molecular organics and NO3. This dual-reaction-site Fenton-like system exhibited ultrahigh extracellular ARG degradation rate (k > 0.9 min-1) and showed the potential for practical wastewater treatment in a membrane filtration process, which provided insights for extracellular ARG removal via catalysts design.

Boosting charge separation in graphdiyne quantum dots/hollow tubular carbon nitride heterojunction for water pollutant degradation

Non-desirable solar energy absorption and poor charge transfer efficiency are two problems that limit the peroxymonosulfate (PMS) photocatalytic techniques. Herein, a metal-free boron-doped graphdiyne quantum dot (BGDs) modified hollow tubular g-C₃N₄ photocatalyst (BGD/TCN) was synthesized to activate PMS and achieved effective space separation of carriers for degradation of bisphenol A. With 0.5 mM PMS, the degradation rate of bisphenol A (20 ppm) was 0.0634 min^-1, 3.7-fold higher than that of TCN itself. The roles of BGDs in the distribution of electrons and photocatalytic property were well identified by experiments and density functional theory (DFT) calculations. The possible degradation intermediate products of bisphenol A were monitored by mass spectrometer and demonstrated to be nontoxic using ecological structure activity relationship modeling (ECOSAR). Finally, this newly-designed material was successfully applied in actual water bodies, which further renders its promising prospect for actual water remediation.