Fe Active Sites Research Articles

Triethylamine regulated MOFs-derived peroxidase-like nanozymes for colorimetric analysis of glyphosate with boosted catalytic activity

Developing accurate and rapid methods for analyzing organophosphorus pesticides is essential to ensure water quality and food safety due to their significant chemical and biological toxicity. This study presents a novel colorimetric sensor for glyphosate based on inhibiting Fe/ZnO nanozyme activity. By doping with iron and modulating the growth process of Fe/Zn MOFs precursors with triethylamine (TEA), Fe/ZnO nanozymes with substantial active surfaces and abundant Fe active sites were derived. The Fe/ZnO possessed excellent peroxidase-like activities, measuring 15.3 and 7.5 times higher than those of the materials synthesized without iron doping (ZnO) and the use of TEA (Fe/ZnO-w), respectively. Glyphosate inhibited the enzyme-like activity of Fe/ZnO by adsorbing on its surface through electrostatic interaction and occupying its catalytic active site. Based on this mechanism, a colorimetric sensing assay was created to directly and selectively detect glyphosate. The linear range for glyphosate detection was 0.02 to 10 mg L−1, with a detection limit (3σ) of 15.6 μg L−1. The proposed method has been successfully applied to the analysis of real samples. Metal oxides derived from well-designed MOFs provide a simple and effective strategy for creating high-performing pesticide detection platforms.

Ni/Fe Fluorides (Hydroxide) Nanocomposite as Efficient OER Catalyst.

The synthesis of efficient oxygen evolution reaction (OER) catalysts that markedly reduce the overpotential over an extended period is crucial for electrolytic water splitting toward hydrogen production. A kind of Ni/Fe fluoride (hydroxide) nanocomposite OER catalyst is designed and prepared by a two-step method for the first time. The nanocomposite with the optimal OER performance (Ni:Fe precursor ratio of 9:1) is observed to possess a nanoparticle morphology with size of about 100 nm. Each nanoparticle hosts extensive nanoregions of Ni4OHF7, NiFeF5∙2H2O and Fe1.9F4.75∙0.95H2O phases. The optimal nanocomposite (Ni:Fe precursor ratio of 9:1) exhibits OER overpotential of merely 208 mV and 349 mV at 10 mA cm-2 and 100 mA cm-2 respectively, tafel slope of 53.1, and outstanding stability for 10 h duration at 100 mA cm-2. The superior OER catalytic performance of the optimal nanocomposite after CV activation is mainly ascribed to the comprehensive catalytic effect of multiple Ni, Fe active sites from three phases, the smaller charge transfer resistance achieved at this particular Ni:Fe precursor ratio. The abundant resources of Ni, Fe, F elements and the superior OER properties of the Ni/Fe fluorides (hydroxide) nanocomposite, makes it a good OER catalyst candidate for electrolytic water splitting toward hydrogen production.

Ultralow Dose Iron-Copper Bimetallic Single-Atom Nanozymes for Efficient Photothermal-Chemodynamic Antibacterial and Wound Healing.

The combination of photothermal and chemodynamic therapy (PTT-CDT) using single-atom nanozymes (SAzymes) shows great promise in combating pathogenic and drug-resistant bacteria. However, the photothermal conversion efficiency and catalytic activity of SAzymes with solely metal sites remain inadequate, often requiring high doses for effectiveness. Herein, a bimetallic single-atomic nanozymes with Fe and Cu active sites (FeCu BSNs) designed is reported for efficient treatment of bacterial infections through hyperthermia-amplified nanozyme catalysis strategy. The FeCu BSNs demonstrate remarkable peroxidase (POD) activity with a specific activity (SA) of 752.25 U mg-1, which is 2.3 folds larger than that of Fe SAzymes (323.45 U mg-1). Additionally, their photothermal effect achieve a photothermal conversion efficiency up to 56.26%, which is two times higher that of Fe SAzymes (29.69%) and Cu SAzymes (25.55%). These enhancements can be attributed to the hybridization of Fe and Cu sites. The FeCu BSNs-mediated PTT-CDT combination therapy demonstrates potent antibacterial effects in both in vitro and in vivo models, attributed to high levels of reactive oxygen species (ROS)generation and hyperthermia. This study effectively validates the application of ultralow-dose bimetallic single-atom nanozymes in PTT-CDT for wound healing, offering a promising approach for enhanced wound recovery.

Catalytic Fe2+ Cation Pair Site for Base-free N-Alkylation of Aromatic Amines with Alcohols.

The development of heterogeneous Fe catalysts is very attractive due to the ubiquitous, abundant, and inexpensive nature of Fe as a resource. However, Fe oxides are commonly inert as catalysts and hence, the design and fabrication of active Fe sites are essential. Herein, the fabrication of an active Fe cation pair site by simple reduction treatment of SiO2-supported FeOx (FeOx/SiO2) is presented. The active Fe cation pair site was formed by the removal of the oxygen atom between Fe cations of the FeOx on SiO2, namely oxygen vacancy formation, which is induced by temperature-controlled reduction treatment. 773 K reduction maximized the Fe cation pair sites without the decomposition of FeOx species, which was an effective catalytic one for the N-alkylation of amines mainly proceeded through Meerwein-Ponndorf-Verley (MPV) type reduction, which is achieved by the stabilization of six-membered ring transition state derived from imines and alcohols over the open active site of the Fe cation pair site.

Eu A-site partial substitution of BiFeO3 as a catalyst for enhanced ofloxacin degradation via singlet oxygen-dominated peroxymonosulfate activation

In this study, the as-synthesized europium (Eu) doped BiFeO3 (EBFO-3) catalyst was employed to activate peroxymonosulfate (PMS) and achieved marked improvement (26.7 %) compared to the BiFeO3 (BFO) catalyst in the degradation of target pollutant ofloxacin (OFL) under identical conditions. The substitution of BiⅢ (ionic radius 1.03 Å) with smaller EuⅢ (ionic radius 0.95 Å) caused larger lattice distortions to promote the formation of more oxygen vacancies and tremendously enhance the production of singlet oxygen (1O2) up to 67.44 % of total reactive oxygen species (ROS). Density functional theory (DFT) calculations further revealed that the electronic structure of iron active sites was effectively modulated to induce reduced covalency of Fe-O bonds, an increase in exposed Fe active sites, and the introduction of additional Eu active sites by partially A-site substituting the more electronegative BiⅢ (2.02) with less electronegative EuⅢ (1.19). The activation of PMS into dominantly selective 1O2 through the substitution of BFO with A-site Eu could improve the applicability of catalysts in treating pollutants in complex water environments, significantly reduce the toxicity of intermediates/products, and provide good insights for the field of water treatment.

Regulating N-doped biochar with Fe-Mo heterojunctions as cathode in long-life zinc-air battery

Carbonaceous electrode loaded nano Mo2C-Fe3N@NCF was synthesized by solvothermal and pyrolysis from soybean straw for high-performance zinc-air batteries (ZABs). The empowered ZAB achieved 1.51 V open-circuit voltage, 88.40 mW cm−2 power density and over 1150 h cycle life. Density functional theory analysis indicates that charge transfer from Mo2C-Fe3N heterogeneous structure to N-doped biochar can significantly reduce the reaction barrier for oxygen reduction/evolution reactions, enhancing the adsorption of oxygen intermediates. Cellulose-derived carbon provides a large specific surface area, and N-doping enhances the conductivity of the resultant biochar, which both play a crucial role in the efficient loading of Fe and Mo active sites. This work inspires the design and application of interfacial engineering on low-cost biochar carriers.

Fe-MOF-based catalysts for oxygen evolution reaction: Microenvironment regulated by organic ligands, metals and carbonization synergistically

In this work, novel catalysts towards oxygen evolution reaction were designed based on Fe-MOF materials. The issues concerning the microenvironment of active sites, such as organic ligands and metal sites, were investigated in detail. Fe-BDC derived from terephthalic acid (H2BDC) displayed better performance compared with Fe-FDCA generated by 2,5-furanedicarboxylic acid (FDCA) due to the difference in electron cloud density of Fe active sites. The additional introduction of metal sites improved the catalytic activity of Co-Fe-BDC and Ni-Fe-BDC with faster reaction kinetics, but its relatively few active sites resulted in oxygen evolution reaction (OER) performance similar to that of the initial Fe-BDC. The pyrolysis of Co/Ni-Fe-BDC afforded carbon-based catalyst Co-Fe-C, possessing an extremely low overpotential (208 mV) at 10 mA/cm2 and high electrocatalytic stability after 36 h of continuous operation, relative to Fe-BDC (249 mV). The high catalytic performance was attributed to the compact and efficient microenvironment of active sites. This study provided a new strategy for the development of efficient and durable electrocatalysts for OER.

Flotation separation of ilmenite and titanaugite modified by Fe2+-assisted peroxymonosulfate oxidation: Performance and activation mechanism

Efficient separation of ilmenite and titanaugite has always been recognized challenge in modern mineral processing. The use of a heterogeneous Fenton-like oxidation process composed of peroxymonosulfate (PMS) and Fe2+ is promising to address this issue. Flotation findings indicated that effective recovery of ilmenite could be achieved under weak acidic conditions, and a TiO2 recovery of 81.56 % and a grade of 32.16 % concentrate was collected. A series of characterization analyses confirmed that the PMS-Fe2+-mediated Fenton-like reaction in the ilmenite system generated more •OH and SO4•- radicals, which oxidized Fe2+ to Fe3+ on its surface, thus improving the active sites on ilmenite surface. Moreover, PMS-Fe2+ promoted the positive shift of surface charge on ilmenite, facilitating NaOL adsorption and making the surface more hydrophobic. NaOL primarily interacted with Fe active sites on the ilmenite surface and Mg2+ and Ca2+ active sites on the titanaugite surface in the formation as chemisorption. Thus, PMS-Fe2+ activated ilmenite mainly via augmenting the quantity and reactivity of Fe active sites on the surface. In summary, these findings provide the innovative pathways to implement the advanced oxidation processes in mineral flotation.

Iron–molybdenum bimetals incorporated montmorillonite-based catalytic ceramic membrane for heterogenous Fenton reaction towards the degradation of micropollutants in water

This study developed an innovative material approach that integrated Fenton catalysis with membrane filtration in a single system using iron–molybdenum bimetal oxides (FeMoO) incorporated montmorillonite (MMT)-based ceramic membrane (FeMoMMTCM) to achieve continuous Fenton reaction for water purification. The embedded bimetallic FeMoO catalyst created abundant active Fe(II) sites on the external and internal surfaces of the ceramic membrane (CM) for H2O2 activation. Using naproxen (NPX) as a model micropollutant in water, the FeMoMMTCM/H2O2 system achieved a 98.6 % removal of NPX (10 mg/L) within a filtration period of 3.4 min through the membrane, in comparison to a 17.5 % removal by FeMoMMTCM filtration with no H2O2 dosing and a 21.1 % removal by the FeMoO-less MMTCM/H2O2 system. The catalytic membrane demonstrated its high NPX removal efficiency over multiple cycles, retaining its effectiveness even in the presence of co-existing ions and organic matter in the water matrix. Furthermore, the FeMoMMTCM/H2O2 system was able to remove nearly 70 % of residual organic pollutants from the actual secondary wastewater effluent. The quenching tests and electro-paramagnetic resonance (EPR) detection confirmed the generation of hydroxyl (OH) and superoxide (O2−) radicals from H2O2. The excellent catalytic performance can be attributed to the Fe-Mo bimetallic catalyst, in which the active Mo(VI)/Mo(IV) cycle can facilitate the Fe(II)/Fe(III) cycle for continuous Fenton reaction. The cost analysis indicates that the low-cost MMT and its low sintering temperature for ceramics would greatly decrease the cost of MMTCM (243.1 US$/m2 vs. 541.5 US$/m2 of alumina-based CM). Overall, the research presents a technical strategy for the fabrication of highly cost-effective catalytic membranes with Fenton reaction for removing micropollutants from water.

Phosphorus‐Enhanced Bimetallic Single‐Atom Catalysts for Hydrogen Evolution

AbstractSingle‐atom catalysts (SACs), where individual metal atoms are anchored on support, hold great promise for electrocatalytic hydrogen evolution reactions (HERs). The inherent simplicity of the single‐atom center restricts opportunities for further enhancement. Binuclear SACs, incorporating two different metal sites, can further improve HER kinetics. However, the underlying mechanisms of the HER at the binuclear sites are complex and not fully understood, hampering the design of new efficient catalyst structures. Here, a comprehensive investigation is presented into phosphorus‐doped iron and cobalt bimetallic SACs supported on nitrogen‐doped graphitic carbon (P/FeCo‐NC), focusing on the potential mechanisms underpinning their enhanced HER activity. P/FeCo‐NC exhibits overpotentials of 38 and 95 mV at 10 mA cm2 in 0.5 m H2SO4 and 1 m KOH, respectively, nearing the acidic performance of commercial Pt/C (33 mV). Theoretical studies reveal that the phosphorus bridge significantly alters the electronic properties of the Fe active sites, while the adjacent Co atoms modulate the electronic environment, further optimizing the hydrogen adsorption‐free energy toward more favorable kinetics. This work highlights the structure‐activity relationships of bimetallic SACs and opens perspectives for future applications.

Heterocyclic effect boosted peroxidase-like activity of MIL(Fe) metal-organic framework for colorimetric assay and dye removal

Metal-organic frameworks (MOFs) have emerged as promising candidates for enzyme mimics due to their abundant pore structures and adjustable active sites. The catalytic activity particularly depends on the electronic character of the organic ligand. In this study, we report an iron-based MOF nanozyme FeTDC, created by replacing the 1,4-dicarboxybenzene ligand with five-membered 2,5-thiophenedicarboxylic acid (H2TDC). In comparison with the phenyl analogue, the sulfur-based heterocyclic ligand demonstrates high electron delocalization, and a low pKa value, which are beneficial for enhancing the metal/ligand interactions. Accordingly, FeTDC can facilitate the oxidation of the benzidine substrate in the presence of H2O2, thereby exhibiting remarkable peroxidase-like activity. The generation of hydroxyl radical (•OH) at the Fe active sites contributes to the catalytic process. Furthermore, the smartphone-assisted colorimetric assay of pyrophosphate was developed with high sensitivity, based on its inhibitory effect. When FeTDC was utilized for the removal of benzidine dye under high-salt condition, a 90 % of removal rate was achieved due to the synergistic effect of enzyme catalysis and physical adsorption. This work presents a novel perspective of heterocyclic effect on the design of MOF nanozymes, thereby expanding their applicability in the control of pollutants.

Efficient atomically dispersed Fe catalysts with robust three-phase interface for stable seawater-based zinc-air batteries

The use of seawater-based electrolytes in zinc-air batteries (S-ZABs) presents significant economic and social benefits and mitigates the demand for scarce freshwater resources. However, it is challenging to achieve a metal-nitrogen-carbon (M-N-C) catalyst that exhibits high resistance to corrosive Cl- in seawater-based electrolytes and possesses a strengthened binding affinity with O2, which enables catalysts with an optimized oxygen reduction reaction (ORR) and enhances the applicability of S-ZABs. Herein, we propose a combined wet chemistry-pyrolysis strategy to obtain atomically dispersed Fe-decorated nitrogen-doped mesoporous carbon spheres (N-MCS-Fe-900). Benefiting from the capacity of the Fe decorations to form the edge-hosted aerophilic FeN4-O2 sites at the optimized three-phase interface, N-MCS-Fe-900 affords the enhanced resistance of the active Fe sites to corrosive Cl-, as well as improved interaction with O2, thereby facilitating the ORR process. As expected, the N-MCS-Fe-900 delivers high half wave potential of 0.90V and kinetic current density of 18.61mAcm−2 at 0.85V in seawater-based 0.1M KOH. More importantly, the S-ZABs equipped with N-MCS-Fe-900 exhibited long-term stability under a high current density for over 140h without voltage decay. Theoretical calculations and electrochemical performance evaluations collectively revealed the superior catalytic efficacy and genesis of this activity in N-MCS-Fe-900, which features edge-hosted FeN4-O2 sites at the stable three-phase interface in seawater electrolytes. This study provides new insights for the advancement of ORR catalysts in sustainable energy conversion technologies for seawater-based electrolytes.

Recycle of Fe/Ca-rich fly ash in preparation of modified porous ceramsite for selective and efficient phosphate recovery

Although wastewater management has systematically developed globally, the removal efficiency of phosphates still posed a serious challenge and attracted worldwide concerns. On the other side, the discharge of fly ash (FA) from sludge incineration also caused serious environmental problems. In this study, Fe/Ca-rich FA was recycled to synthesize a porous ceramsite (modified CFA) through a non-sintered method. It could be an efficient adsorbent for phosphate recovery in virtue of abundant adsorption sites, accompanied by its low-cost and environmental friendliness. The phosphate adsorption capacity was 26.31 mg-P·g-1 for modified CFA, and its average adsorption rate could reach 1.344 mg-P·(g·day)-1 in the first 2 days. While it could also efficiently immobilize phosphate for a quite long period in the dynamic system effluent. According to electron microscopic and spectroscopic characterizations, modified CFA was indicated to chemisorb and immobilize phosphates via multiple interface interactions. Phosphates were firstly H-bonded with the surface Fe/Ca-OH of modified CFA and then rapidly coordinate with active Fe sites through a ligand exchange mechanism. When the exposed Fe sites had been saturated-adsorbed, inner-sphere Ca-O-P coordination would be further formed. In summary, this study provides a promising FA-derived adsorbent and realizes the efficient P pollution management with low cost and minimal environmental risks, which would be a potential waste-to-wealth strategy for further applications.

Role of citric acid in selective flotation of limonite from quartz using sodium oleate as collector

The issue that eliminating the negative effects of inevitable ions in the pulp on mineral flotation separation has attracted widespread attention. To achieve the efficient flotation separation of limonite from quartz, citric acid was utilized as a depressant for quartz in this paper. The solubility of limonite was studied using inductively coupled plasma tests (ICP), and the effect of Fe3+ and citric acid on the separation of limonite from quartz under sodium oleate (NaOL) system was investigated using batch flotation tests. The underlying mechanisms were probed through zeta potential measurements, infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and contact angle detection. It was found that limonite could dissolve a certain number of Fe3+ in the pulp. These Fe3+ adsorbed onto quartz and acted as the active sites to promote the adsorption of NaOL, thereby enhancing quartz flotation evidently and deteriorating the separation of limonite from quartz. Fortunately, citric acid could depress the flotation of iron-activated quartz quite well by covering and desorbing the active sites of Fe3+ and causing the steric hindrance to prohibit the adsorption of NaOL. Meanwhile, the hydrophilic groups in citric acid could also increase the surface hydrophilicity of quartz and enhance the inhibitory effect. In comparison, Fe3+ and citric acid had little effect on the adsorption of NaOL onto limonite since its surface exposed enough Fe-active sites for the adsorption of NaOL. Thus, the difference in the floatability of limonite and quartz was enlarged, eventually achieving a better separation of them. This research sheds new light on the role of citric acid in the selective separation of quartz from soluble iron minerals.

Facile synthesis of graphitized carbon nanosheets from Chlorella with multiple Fe active sites to modify separator for efficient Li-S batteries

Li-S battery as an alternative to next-generation battery systems suffers from electrical insulating properties of sulfur, “shuttle effects” and slow kinetics of lithium polysulfides (LiPSs). Separator modification via catalysts with multiple scales of active sites are great potential; however, the preparation of such a kind of catalysts is still complex and tedious. Here, we developed a facile pyrolysis strategy to fabricate multiple Fe active sites on N-doped porous graphitized carbon nanosheets (Fe-NG) from Chlorella, including atomically dispersed Fe single atoms, Fe nanoclusters and carbon-coated Fe nanoparticles, which enhanced the affinity to LiPSs and accelerated their conversion kinetics. As Fe-NG was utilized to modify the separators, the resulting Li-S battery demonstrated an initial discharge capacity of 1062.1 mAh g−1 at 1 C and maintained at 678 mAh g−1 after 500 cycles with the average capacity decay rate of 0.072 % per cycle. This work provides a rational design and large-scale preparation routes for separator modifying catalysts with heterogeneous active species on biomass-derived carbons.

Strategy of constructing D-A structure and accurate active sites over graphitic carbon nitride nanowires for high efficient photocatalytic nitrogen fixation

Constructing photocatalysts for the stable and efficient production of NH3 is of excellent research significance and challenging. In this paper, the electron acceptor 5-amino-1,10-phenanthroline (AP) is introduced into the electron-donor graphitic carbon nitride (CN) framework by a simple heated copolymerization method to construct a donor–acceptor (D-A) structure. Subsequently, the phenanthroline unit is coordinated with transition metal Fe3+ ions to obtain the photocatalyst Fe(III)-0.5-AP-CN with better nitrogen fixation performance, and the average NH3 yield can reach 825.3 μmol g−1 h−1. Comprehensive experimental results and theoretical calculations show that the presence of the D-A structure can induce intramolecular charge transfer, effectively separating photogenerated electrons and holes. The Fe active sites can improve the chemisorption energy for N2, enhance the N-Fe bonding, and better activate the N2 molecule. Therefore, the synergistic effect between the construction of the D-A structure and the stably dispersed Fe active sites can enable CN to achieve high-performance N2 reduction to produce NH3.

Modifying the second coordination spheres of Fe active sites for electrocatalytic nitric oxide reduction in realistic electrochemical environment

The first and second coordination spheres in the coordination microenvironment may regulate the electronic structure of single-metal atoms supported on carbon matrix, which in turn modulates the catalyst’s catalytic activity. Simulating the kinetic process of electrocatalytic nitric oxide reduction reaction (NORR) by the theoretical modeling of electrochemical microenvironments helps understand the theoretical structure–activity relationship and guides a more rational design of electrocatalysts. In this study, density functional theory calculations combined with a constant-potential/hybrid-solvent model and microkinetic modeling are employed to study NORR mechanism on the carbon-based FeN4, FeN4-O and FeN4-B catalysts with different electronegativity atoms in the second coordination spheres under −1.00 ∼ 0.40 V vs. RHE. The free energy changes of all elementary reactions for NORR on the catalysts reveal that the optimal pathways for NORR on FeN4 produce both ammonia and hydroxylamine, proceeding through the reaction intermediates *NHOH. Within −1.00 ∼ -0.37 V vs. RHE, the kinetic barriers of the rate-determining steps for NORR increase sequentially on FeN4, FeN4-O, and FeN4-B, corresponding to the sequentially decreasing reaction rate constants. At −6.00 mA∙cm−2, the electrode potential for ammonia production on FeN4 catalyst is the lowest among the catalysts at −0.70 V vs. RHE, indicating it has higher electrocatalytic activity.

Cation-induced interface electric field redistribution and molecular orbital coupling in Co-FeS/MoS2 for boosting electrocatalytic overall water splitting

A green hydrogen economy requires efficient bifunctional electrocatalysts for simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this study, a mild sulfuration strategy was used to create a Co-FeS/MoS2 catalyst from metal-organic frameworks (MOFs) on foam nickel. This catalyst exhibits exceptional activity in 1 M KOH, only requiring ultralow overpotentials of 63 mV and 230 mV to achieve current densities of 10 mA cm−2 and 100 mA cm−2 for the HER and OER processes. Additionally, it achieves a low cell voltage of 1.45 V at 10 mA cm−2, surpassing reported catalysts. DFT calculations and XPS tests show that Co introduction induces high-valence Fe active sites and facilitates interface electric field redistribution. Crystal orbital Hamilton population (COHP) calculations reveal d-p orbital hybridization, enhancing conductivity and charge transfer kinetics. This research sheds light on the catalytic impacts of metal cations on transition metal sulfides to design high efficient electrocatalysts.

Selective enhancement of degradation capacity of organic pollutants based on low-temperature plasma: The role of specificity of catalysts and reactive oxygen species

The use of low-temperature plasma systems to remove refractory organic pollutants in municipal sewage has achieved preliminary results. However, the relationships between the role of specificity of catalysts and reactive species need to be further clarified. Here, an electrostatic spinning strategy by doping energetic MOF and Fe-MOF to adjust the structure and components of catalysts, and achieve the selective synergies removal of contaminants including bisphenols A, tetracycline, atrazine, acid orange 7, and Congo red. This can be attributed to the doping of the energetic MOF, which results in more dispersed Fe active sites and a more developed pore structure, which in turn drastically increases the utilization of the active site. The frontier molecular orbital theory and the Fukui function elaborate the possible degradation pathways. This work illustrated the relationship between the selection of catalysts, the production of active species, and the specific removal of pollutants in DBD systems.

Electron Reservoir Effect of Adjacent Fe Nanoclusters Boosts Atomic Fe Active Sites on Porous Carbon for the Both Electrocatalytic Oxygen Reduction and CO2 Reduction Reaction.

Electrochemical oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR) are greatly significant in renewable energy-related devices and carbon-neutral closed cycle, while the development of robust and highly efficient electrocatalysts has remained challenges. Herein, a hybrid electrocatalyst, featuring axial N-coordinated Fe single atom sites on hierarchically N, P-codoped porous carbon support and Fe nanoclusters as electron reservoir (FeNCs/FeSAs-NPC), is fabricated via in situ thermal transformation of the precursor of a supramolecular polymer initiated by intermolecular hydrogen bonds co-assembly. The FeNCs/FeSAs-NPC catalyst manifests superior oxygen reduction activity with a half-wave potential of 0.91V in alkaline solution, as well as high CO2 to CO Faraday efficiency (FE) of surpassing 90% in a wide potential window from -0.40 to -0.85V, along with excellent electrochemical durability. Theoretical calculations indicate that the electron reservoir effect of Fe nanoclusters can trigger the electron redistribution of the atomic Fe moieties, facilitating the activation of O2 and CO2 molecules, lowering the energy barriers for rate-determining step, and thus contributing to the accelerated ORR and CO2RR kinetics. This work offers an effective design of electron coupling catalysts that have advanced single atoms coexisting with nanoclusters for efficient ORR and CO2RR.