Electrocatalytic Reduction Research Articles

In situ Raman investigation to electrochemical synthesis of ammonia on Pd nanocrystals.

Nitrate and nitrite are widely present in industrial wastewater and domestic sewage, so electrocatalytic reduction of both nitrate and nitrite to ammonia synthesis is considered to be a sustainable development approach. Pd nanostructures have attracted much attention because of their high activity in catalyzing the nitrate electrochemical reduction reaction. Here we prepare Pd nanocube and octahedron for the electrochemical reduction of nitrate and nitrite. It is found that Pd octahedron shows slightly higher activity toward nitrate reduction than Pd nanocube, while for nitrite reduction, Pd octahedron shows much higher activity than Pd nanocube. The ammonia yield rate is more potential-dependent. In situ Raman characterization further confirms the existence of adsorbed ammonia on the surface of nanocube and octahedron, indicating similar reduction pathways on (111)-facet octahedron and (100)-facet nanocube.

Tandem electrocatalysis for CO2 reduction to multi-carbons

Tandem electrocatalysis for CO2 reduction to multi-carbons

Regulating Fe Intermediate Spin States via FeN4‐Cl‐Ti Structure for Enhanced Oxygen Reduction

AbstractModulating the spin states of FeN4 moieties is critical for enhancing the electrocatalytic oxygen reduction reaction (ORR). In this study, Ti4N3Clx and Ti4N3Ox MXenes are synthesized and functionalized with iron phthalocyanine (FePc) to form model catalysts with well‐defined FeN4‐Cl‐Ti and FeN4‐O‐Ti structures, respectively. The FeN4‐Cl‐Ti structure, formed within the Ti4N3Clx/FePc composite, enables precise modulation of FeN4 spin states from low to intermediate spin, significantly enhancing ORR performance. In contrast, the FeN4‐O‐Ti structure in Ti4N3Ox/FePc shows less effective spin state modulation, leading to comparatively lower ORR activity. Compared to FePc and Ti4N3Ox/FePc, Ti4N3Clx/FePc demonstrates superior electrochemical performance, with an ORR half‐wave potential of +0.91 V versus RHE and doubled power densities in Zn–air batteries (214.5 mW cm−2). Theoretical studies confirm that the intermediate spin states induced by the weak‐field ligand‐modified FeN4‐Cl‐Ti structure in Ti4N3Clx/FePc facilitate electron filling in the antibonding orbital composed of Fe 3dz2 and O2 π* orbitals, greatly enhancing O₂ activation and ORR activity. These findings underscore the superior catalytic properties of FeN4‐Cl‐Ti compared to FeN4‐O‐Ti, advancing the understanding of spin state‐related catalytic mechanisms and guiding the design of high‐performance ORR catalysts.

Unveiling F-coordination tuning of dense Fe-N4 active sites via nitrogen fixation over advanced electrocatalysts

The manuscript presents a significant advancement in the field of electrocatalytic nitrogen fixation by unveiling the role of fluorine coordination in tuning the activity of atomically dispersed iron-nitrogen (Fe-N4) active sites within porous carbon (PC). The innovative approach employs chemical vapor deposition (CVD) to fabricate F-Fe-NC active sites, which, upon fluorination, modulate the electronic configuration of iron, enhancing nitrogen adsorption and activation. The F-Fe-NC catalyst demonstrated a remarkable enhancement in electrocatalytic nitrogen reduction reaction (NRR) performance, achieving an ammonia yield rate (RNH3) of 125.49 μg h−1 mgcat.−1 and a Faradaic efficiency (FE) of 25.19 %. In-situ electrochemical mass spectrometry and Density Functional Theory (DFT) calculations were utilized to dissect the NRR kinetics and elucidate the underlying reaction mechanism, identifying the potential-determining step. The study introduces a novel, high-performance catalyst for electrocatalytic NRR and provides a practical strategy for optimizing the active-site microenvironment, laying the groundwork for the future commercial application of electrocatalytic NRR processes.

Heterometallic Transition Metal Oxides Containing Lewis Acids as Molecular Catalysts for the Reduction of Carbon Dioxide to Carbon Monoxide with Bimodal Activity.

Electrocatalytic CO2 reduction (e-CO2RR) to CO is replete with challenges including the need to carry out e-CO2RR at low overpotentials. Previously, a tricopper-substituted polyoxometalate was shown to reduce CO2 to CO with a very high faradaic efficiency albeit at -2.5 V versus Fc/Fc+. It is now demonstrated that introducing a nonredox metal Lewis acid, preferably GaIII, as a binding site for CO2 in the first coordination sphere of the polyoxometalate, forming heterometallic polyoxometalates, e.g., [SiCuIIFeIIIGaIII(H2O)3W9O37]8-, leads to bimodal activity optimal both at -2.5 and -1.5 V versus Fc/Fc+; reactivity at -1.5 V being at an overpotential of ∼150 mV. These results were observed by cyclic voltammetry and quantitative controlled potential electrolysis where high faradaic efficiency and chemoselectivity were obtained at -2.5 and -1.5 V. A reaction with 13CO2 revealed that CO2 disproportionation did not occur at -1.5 V. EPR spectroscopy showed reduction, first of CuII to CuI and FeIII to FeII and then reduction of a tungsten atom (WVI to WV) in the polyoxometalate framework. IR spectroscopy showed that CO2 binds to [SiCuIIFeIIIGaIII(H2O)3W9O37]8- before reduction. In situ electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) with pulsed potential modulated excitation revealed different observable intermediate species at -2.5 and -1.5 V. DFT calculations explained the CV, the formation of possible activated CO2 species at both -2.5 and -1.5 V through series of electron transfer, proton-coupled electron transfer, protonation and CO2 binding steps, the active site for reduction, and the role of protons in facilitating the reactions.

Alkali Metal Cations Induce Structural Evolution on Au(111) During Cathodic Polarization.

The activity of the electrocatalytic CO2 reduction reaction (CO2RR) is substantially affected by alkali metal cations (AM+) in electrolytes, yet the underlying mechanism is still controversial. Here, we employed electrochemical scanning tunneling microscopy and in situ observed Au(111) surface roughening in AM+ electrolytes during cathodic polarization. The roughened surface is highly active for catalyzing the CO2RR due to the formation of surface low-coordinated Au atoms. The critical potential for surface roughening follows the order Cs+ > Rb+ > K+ > Na+ > Li+, and the surface proportion of roughened area decreases in the order of Cs+ > Rb+ > K+ > Na+ > Li+. Electrochemical CO2RR measurements demonstrate that the catalytic activity strongly correlates with the surface roughness. Furthermore, we found that AM+ is critical for surface roughening to occur. The results unveil the unrecognized effect of AM+ on the surface structural evolution and elucidate that the AM+-induced formation of surface high-activity sites contributes to the enhanced CO2RR in large AM+ electrolytes.

Atomically dispersed Co-based species containing electron withdrawing groups for electrocatalytic oxygen reduction reactions.

Single-atom-based catalysts are a promising catalytic system with advantages of molecular catalysts and conductive supports. In this work, a new hybrid material (CoF/NG) is produced using a low-temperature reaction between an organometallic complex (Co(C5HF6O2)2) (CoF) and N-doped reduced graphene oxide (NG). CoF contains electron-withdrawing CF3 groups in the ligand around a Co atom. Microscopic and chemical characterization studies reveal that Co-based species are coordinated to N sites of NG and molecularly dispersed on the surface of NG. The CoF/NG hybrid shows improved electrocatalytic properties, such as onset (0.91 V) and half-wave (0.80 V) potentials, for the electrochemical oxygen reduction reaction (ORR) relative to the NG material. Control experiments reveal that Co-(N)graphene acts as a major active species for ORR. CoF/NG shows moderate cycling durability and microscopy measurements of CoF/NG-after-cycle indicate the formation of nanoparticles after electrocatalytic measurements. All experimental data support that the incorporation of Co-based organometallic species containing electron-withdrawing groups around the metal center onto the graphene-based networks improves the electrocatalytic ORR performance but diminishes the electrocatalytic stability of the active species.

Thiacalix[4]arene-Stabilized Sb/Ag Bimetallic Nanoclusters: Elucidating the Effects of Sb Doping on Electrocatalytic CO2 Reduction in Ag Clusters.

Accurately identifying the metal doping effects within heterogeneous catalysts presents a formidable challenge due to the complex nature of controlling the interfacial chemistry at the molecular level. Herein, we use two sets of atomically precise nanoclusters to demonstrate the impact of Sb doping on the electrocatalytic CO2 reduction activity in Ag nanoclusters. Leveraging the unique properties of the thiacalix[4]arene, we have pioneered a methodology for incorporating catalytic Ag1+ and Sb3+ sites, culminating in the synthesis of the pioneering Sb-Ag bimetallic cluster, Sb2Ag11. We refined this structure by replacing the two Sb3+ sites with Na+ sites, resulting in a Na2Ag10 cluster. Broadening our investigative scope, we isolated the core components from both Sb2Ag11 and Na2Ag10 and obtained two clusters: Sb2Ag4 and Ag4. The subtle compositional variations between two pairs of structurally analogous clusters, Sb2Ag11 and Na2Ag10, as well as Sb2Ag4 and Ag4, create opportunities to investigate how the Sb doping impacts the catalytic activity of Ag clusters. Clearly, compared to the undoped clusters, those doped with Sb exhibit higher catalytic current densities and enhanced CO selectivity. The theoretical calculations suggest that Sb doping can enhance the adsorption barrier of *H, thereby inhibiting hydrogen evolution activity and conversely promoting eCO2RR to CO activity.

F‐π* Back Bonding Orbital Induced by Lutetium‐Based Conducting MOF Promotes Highly Selective CO 2 to CH 4 at Low Potential

The research on electrocatalytic carbon dioxide reduction (ECR) catalysts using renewable energy is particularly crucial in energy conversion studies, especially for viable hydrocarbon production. This study employs density functional theory calculations to screen a series of non‐radioactive lanthanide two‐dimensional metal‐organic frameworks (MOFs) for product selectivity in ECR. Based on theoretical screening, our focus is on a lutetium (Lu)‐based conducting MOF (Lu‐HHTP), which exhibits a Faradaic efficiency of approximately 77% for methane (CH4) production and maintains a stable current density of ‐280 mA/cm2 at ‐1.1 V vs. RHE. In situ electrochemical experiments and material characterization demonstrate that the Lu sites possess high coordination stability and structural recoverability during catalytic CO2 reduction, attributed to the overlap between Lu's f‐orbitals and the π*‐orbitals of the ligand O, and the formation of back bonding orbitals between the f‐orbitals of Lu and the π* orbitals of CO contribute increasing CH₄ selectivity and lowering the potential. This study leverages rare‐earth MOF‐type materials, offering a novel approach to addressing low conductivity and stabilizing rare‐earth materials, thereby establishing a theoretical framework for the conversion of linearly adsorbed *CO into hydrocarbons.

F-π* Back Bonding Orbital Induced by Lutetium-Based Conducting MOF Promotes Highly Selective CO 2 to CH 4 at Low Potential.

The research on electrocatalytic carbon dioxide reduction (ECR) catalysts using renewable energy is particularly crucial in energy conversion studies, especially for viable hydrocarbon production. This study employs density functional theory calculations to screen a series of non-radioactive lanthanide two-dimensional metal-organic frameworks (MOFs) for product selectivity in ECR. Based on theoretical screening, our focus is on a lutetium (Lu)-based conducting MOF (Lu-HHTP), which exhibits a Faradaicefficiency of approximately 77% for methane (CH4) production and maintains a stable current density of -280 mA/cm2at -1.1 V vs. RHE. In situ electrochemical experiments and material characterization demonstrate that the Lu sites possess high coordination stability and structural recoverability during catalytic CO2reduction, attributed to the overlap between Lu's f-orbitalsand the π*-orbitals of the ligand O, and the formation of back bonding orbitals between the f-orbitals of Lu and the π* orbitals of CO contribute increasing CH₄selectivity and lowering the potential. This study leverages rare-earth MOF-type materials, offering a novel approach to addressing low conductivity and stabilizing rare-earth materials, thereby establishing a theoretical framework for the conversion of linearly adsorbed *CO into hydrocarbons.

One stone, three birds: The enhanced electrocatalytic sensing for 4-nitrophenol derived from the triple-strategies regulated interface of Co-ZIF-L/NCS/CP

4-nitrophenol (4-NP) is one of the most toxic organic pollutants, which causes severe damages to organism and environment. The electrochemical analysis for 4-NP proceeded slowly due to the hard electrocatalytic reduction of 4-NP, the limited catalytic sites and poor stability of the electrodes. In this paper, by the “one stone with three birds” strategy, a series of three-phase interfaces n-Co-ZIF-L/NCS-X/CP were constructed for the enhanced electrocatalytic sensing for 4-NP. By the dual in-situ strategy, NiCo2S4 (NCS) was first electrodepositing on carbon paper (CP) and then Co-based metal-organic framework (Co-ZIF-L) was grown on the NiCo2S4, which not only introduced abundant metal active sites, but also improved the interfacial stability due to the strong bond interactions; By the dual-regulation strategy, the structures and composites of NiCo2S4 and Co-ZIF-L were precisely regulated. The heterogeneous structure of lamellar and nanoflower-like NiCo2S4, as well as the two-dimensional leaf-like Co-ZIF-L, made more catalytic sites be exposed and improved the electrocatalytic activity; The triple synergistic effect among Co-ZIF-L, NiCo2S4 and CP effectively optimized the electronic structure of the interfacial active sites and widen the electron transport channels, thus accelerated the electrochemical sensing process. In addition, the three-phase interface of 0.3-Co-ZIF-L/NCS-20/CP was successfully applied for 4-NP detection in the practical samples of lake water, seawater and industrial wastewater.

Electrocatalytic Conversion of CO2 to Formic Acid: A Journey from 3d-Transition Metal-Based Molecular Catalyst Design to Electrolyzer Assembly.

ConspectusElectrochemical CO2 reduction to obtain formate or formic acid is receiving significant attention as a method to combat the global warming crisis. Significant efforts have been devoted to the advancement of CO2 reduction techniques over the past few decades. This Account provides a unified discussion on various electrochemical methodologies for CO2 to formate conversion, with a particular focus on recent advancements in utilizing 3d-transition-metal-based molecular catalysts. This Account primarily focuses on understanding molecular functions and mechanisms under homogeneous conditions, which is essential for assessing the optimized reaction conditions for molecular catalysts. The unique architectural features of the formate dehydrogenase (FDH) enzyme provide insight into the key role of the surrounding protein scaffold in modulating the active site dynamics for stabilizing the key metal-bound CO2 intermediate. Additionally, the protein moiety also triggers a facile proton relay around the active site to drive electrocatalytic CO2 reduction forward. The fine-tuning of FDH machinery also ensures that the electrocatalytic CO2 reduction leads to the production of formic acid as the major yield without any other carbonaceous products, while limiting the competitive hydrogen evolution reaction. These lessons from the enzymes are key in designing biomimetic molecular catalysts, primarily based on multidentate ligand scaffolds containing peripheral proton relays. The subtle modifications of the ligand framework ensure the favored production of formic acid following electrocatalytic CO2 reduction in the solution phase. Next, the molecular catalysts are required to be mounted on robust electroactive surfaces to develop their corresponding heterogeneous versions. The surface-immobilization provides an edge to the molecular electrocatalysts as their reactivity can be scaled up with improved durability for long-term electrocatalysis. Despite challenges in developing high-performance, selective catalysts for the CO2 to formic acid transformation, significant progress is being made with the tactical use of graphene and carbon nanotube-based materials. To date, the majority of the research activity stops here, as the development of an operational CO2 to formic acid converting electrolyzer prototype still remains in its infancy. To elaborate on the potential future steps, this Account covers the design, scaling parameters, and existing challenges of assembling large-scale electrolyzers. A short glimpse at the utilization of electrolyzers for industrial-scale CO2 reduction is also provided here. The proper evaluation of the surface-immobilized electrocatalysts assembled in an electrolyzer is a key step for gauging their potential for practical viability. Here, the key electrochemical parameters and their expected values for industrial-scale electrolyzers have been discussed. Finally, the techno-economic aspects of the electrolyzer setup are summarized, completing the journey from tactical design of molecular catalysts to their appropriate application in a commercially viable electrolyzer setup for CO2 to formate electroreduction. Thus, this Account portrays the complete story of the evolution of a molecular catalyst to its sustainable application in CO2 utilization.

Atmosphere Induces Tunable Oxygen Vacancies to Stabilize Single‐Atom Copper in Ceria for Robust Electrocatalytic CO2 Reduction to CH4

Electrochemical carbon dioxide reduction (ECO2RR) shows great potential to create high‐value carbon‐based chemicals, while designing advanced catalysts at the atomic level remains challenging. The ECO2RR performance is largely dependent on the catalyst microelectronic structure that can be effectively modulated through surface defect engineering. Here, we provide an atmosphere‐assisted low‐temperature calcination strategy to prepare a series of single‐atomic Cu/ceria catalysts with varied oxygen vacancy concentrations for robust electrolytic reduction of CO2 to methane. The obtained Cu/ceria catalyst under H2 environment (Cu/ceria‐H2) exhibits a methane Faraday efficiency (FECH4) of 70.03% with a turnover frequency (TOFCH4) of 9946.7 h−1 at an industrial‐scale current density of 150 mA cm−2 in a flow cell. Detailed studies indicate the copious oxygen vacancies in the Cu/ceria‐H2 are conducive to regulating the surface microelectronic structure with stabilized Cu+ active center. Furthermore, density functional theory calculations and operando ATR‐SEIRAS demonstrate that the Cu/ceria‐H2 can markedly enhance the activation of CO2, facilitate the adsorption of pivotal intermediates *COOH and *CO, thus ultimately enabling the high selectivity for CH4 production. This study presents deep insights into designing effective electrocatalysts for CO2 to CH4 conversion by controlling the surface microstructure via the reaction atmosphere.

Atmosphere Induces Tunable Oxygen Vacancies to Stabilize Single‐Atom Copper in Ceria for Robust Electrocatalytic CO2 Reduction to CH4

Electrochemical carbon dioxide reduction (ECO2RR) shows great potential to create high‐value carbon‐based chemicals, while designing advanced catalysts at the atomic level remains challenging. The ECO2RR performance is largely dependent on the catalyst microelectronic structure that can be effectively modulated through surface defect engineering. Here, we provide an atmosphere‐assisted low‐temperature calcination strategy to prepare a series of single‐atomic Cu/ceria catalysts with varied oxygen vacancy concentrations for robust electrolytic reduction of CO2 to methane. The obtained Cu/ceria catalyst under H2 environment (Cu/ceria‐H2) exhibits a methane Faraday efficiency (FECH4) of 70.03% with a turnover frequency (TOFCH4) of 9946.7 h−1 at an industrial‐scale current density of 150 mA cm−2 in a flow cell. Detailed studies indicate the copious oxygen vacancies in the Cu/ceria‐H2 are conducive to regulating the surface microelectronic structure with stabilized Cu+ active center. Furthermore, density functional theory calculations and operando ATR‐SEIRAS demonstrate that the Cu/ceria‐H2 can markedly enhance the activation of CO2, facilitate the adsorption of pivotal intermediates *COOH and *CO, thus ultimately enabling the high selectivity for CH4 production. This study presents deep insights into designing effective electrocatalysts for CO2 to CH4 conversion by controlling the surface microstructure via the reaction atmosphere.

Manganese Doped‐Nitrogenated Carbon as an Efficient Catalyst for Acidic Electrocatalytic Reduction of CO2

AbstractRenewable electricity‐driven CO2 electroreduction to value‐added chemicals is a feasible approach to alleviate both environmental and energy issues. However, CO2 reduction reaction (CO2RR) systems in alkaline electrolytes are constrained by intrinsic limitations such as salt accumulation that impede further industrialization. Herein, an atomically dispersed Mn doped‐nitrogen carbon (AD MnNC) catalyst is developed to electrochemically reduce CO2 to CO in both neutral and acidic media. Benefiting from well‐dispersed MnNx sites, the maximum CO Faradaic efficiency (FECO) reaches ≈100% at −0.73 V versus reversible hydrogen electrode (RHE) with CO current density (JCO) of 20.4 mA cm−2 in neutral 0.5 m KHCO3. Due to diminished *H adsorption, AD MnNC achieves a FECO of 85.3% at pH 2.0, effectively suppressing the hydrogen evolution reaction (HER) in an acidic electrolyte. The mechanistic study reveals that AD MnNC accelerates the production of *COOH intermediates through a proton‐coupled electron transfer (PCET) pathway and thus promotes CO formation.

Modulation of charge structure in Bi/Bi2O3-In2O3@C for efficient CO2 electroreduction to formate

Electrocatalytic CO2 reduction reaction (ECO2RR) to value-added chemicals is of significant importance to control CO2 emission and reach carbon neutrality. Herein, Bi/Bi2O3-In2O3@C electrocatalyst with nanosheet arrays is successfully fabricated by a facile solvothermal with subsequent calcination process. It is found that the electron structure of Bi/Bi2O3-In2O3@C can be adjusted by the synergistic effects of Bi-In hetero-diatoms, which can significantly enhance its inherent catalytic activity. As expected, it requires a maximum HCOOH faradaic efficiency (FEHCOOH) of 97.6 % at −1.1 V vs. Reversible Hydrogen Electrode (RHE), which further delivers over 90 % at a wide potential range of −0.8 to −1.4 V vs. RHE, and exhibits high stability of 90.1 % over 60-h long-term test. In-situ Raman analysis is performed to explore the mechanism of its excellent stability. Meanwhile, in-situ attenuated total reflection-Fourier-transform infrared (ATR-FTIR) analysis combined with theoretical calculations reveal that the hetero-bridging absorption of *OCHO and d-d orbital coupling effect can regulate d-band center of Bi/Bi2O3-In2O3@C and improve its density of states around Ef, moderating free energy of intermediates, thereby the improved formate production performance can be seen.

Advancements in Amorphous Oxides For Electrocatalytic Carbon Dioxide Reduction

Electrocatalytic CO2 reduction (ECR) is a crucial energy conversion technology that transforms CO2 into value-added chemicals, reducing reliance on fossil fuels and advancing energy transitions. Designing high-performance catalysts is pivotal for widespread adoption of CO2 reduction reactions, aiming for high activity, selectivity, and stability. Amorphous oxides represent a burgeoning frontier in this field, attracting attention due to their abundant active sites that refine the catalyst structure-performance relationship. This paper aims to provide an overview of recent advances in using amorphous oxides for ECR. We begin by introducing the basic theory of electrocatalytic CO2 reduction, followed by discussing current synthesis approaches for amorphous oxides in CO2 reduction, focusing on optimization strategies for these catalysts. Finally, we address challenges and future perspectives of amorphous oxides in ECR, aiming to foster the development of more efficient catalyst designs.

Transition metal atoms embedded into B/N co-doped graphene as electrocatalysts toward nitrogen reduction reaction: Search for the optimal combination

The catalytic performance of a series of single transition metal (TM = 3d, 4d, and 5d series) atoms anchored on B/N co-doped graphene (BxNy@Gra) toward electrocatalytic nitrogen reduction reaction (eNRR) was systematically investigated by first-principles calculations. Among 180 possible materials, four catalysts (Tc-B1N3@Gra, Os-B2N2α@Gra, Re-B2N2γ@Gra, Nb-B3N1@Gra) feature the highest activity with UL no higher than 0.31 V. Interestingly, a volcano curve between UL and ΔEads(*NNH) can be established, so ΔEads(*NNH) can be applied as a descriptor to unveil the structure-activity relationship and characterize the activity of catalysts. The properties, thermal stability, and selectivity for the four catalysts were analyzed. Os-B2N2α@Gra is identified as a promising catalyst in this work for catalyzing N2 electroreduction to NH3 owing to its potent catalytic activity (UL = −0.28 V), high stability and distinct selectivity. This work can give some meaningful guidance for rapid screening and the rational design of efficient single-atom catalysts for electrocatalytic ammonia synthesis and other related electrochemical reaction. We expect that the present study will inspire and promote the efforts from both experimental and theoretical in this direction.

Stabilization of Cu2O catalyst via strong electronic interaction for selective electrocatalytic CO2 reduction to ethanol

While cuprous oxide (Cu2O) remains the most efficient and viable electrocatalyst for the electrochemical conversion of CO2 to ethanol, its reduction to Cu during the catalytic CO2RR process poses a barrier to its industrial application. To address this challenge, we have reported a highly stable Cu2O-based catalyst by introducing pseudo-capacitive NiCo2O4 intermediate layers. The current densities observed on the surface of the prepared NF@NiCo2O4@Cu2O remained consistent over a 15-hour stability test, demonstrating excellent durability that exceeds that of the NF@Cu2O electrode by more than 200 %. Experimental characterization and DFT analysis indicate that the exceptional stability is primarily attributed to the pseudo-capacitive NiCo2O4 interlayer with cyclic charge–discharge properties, where NiCo2O4 can capture and eliminate accumulated reduced electrons around Cu2O under strong electronic interactions and release electrons through catalytic reduction to produce hydrogen. Furthermore, the NiCo2O4@Cu2O (111) heterostructure significantly reduces the Gibbs free energy (ΔG) required for C-C coupling of *CO intermediates compared to Cu2O (111). This mechanism establishes a cyclic charge–discharge process in order to prevent reduction of Cu2O into copper monomers. As a result, NF@NiCo2O4@Cu2O demonstrates a C2H5OH faradaic efficiency of 56.9 % at −0.5 V vs. RHE, surpassing many other Cu-based catalytic electrodes. This work provides new insights into studying strong electronic interaction structures to eliminate electron enrichment at the catalytic site for stabilizing catalysts and also offers an effective strategy for designing catalysts that maintain long-term stability in industrial applications.

A high-throughput screening of catalyst for efficient nitrogen fixation: Transition metal single-atom anchored on an emerging synthesized biphenyl network

Synthesizing efficient and selective green ideal catalysts has been an increasingly critical, yet unsolved, issue for the ammonia synthesis industry, hindering the growing global demand for environmental protection and energy efficiency. Electrocatalytic nitrogen reduction reaction (eNRR) is a promising technology for low-energy ammonia synthesis. However, designing efficient electrocatalysts for NRR remains challenging. The emergence of graphene-like substrates offers exciting prospects for addressing this challenge and facilitating single-atom catalysts in eNRR. Here, we report the innovative selection of a recently synthesized two-dimensional biphenyl network (2D BPN) compound as a substrate. Its excellent conductivity and porosity enable stable transition metal atoms (TMs) support for constructing eNRR electrocatalysts. we evaluated the feasibility of 23 TMs anchored on BPN for eNRR by high-throughput first-principles calculations. Through a systematic five-step strategy, we identified several single-atom catalysts (SACs) with potential for eNRR, including Mo@BPN, V@BPN, W@BPN, and Re@BPN. Among them, Mo@BPN exhibited the best balance in the adsorption of key reaction intermediates (e.g., N2H and NH3) and demonstrated a low limiting potential (-0.37 V). In addition, the underlying mechanism of NRR activity was elucidated by analyzing the extrinsic patterns revealed through the screened catalysts. A triangular volcano diagram, incorporating the initial protonation step, adsorption free energy, and final protonation step, revealed the NRR activity trend. Overall, this study provides a solid theoretical foundation and valuable guidance for future experimental exploration of efficient electrocatalysts for ammonia synthesis on BPN. Crucial insights into the theoretical design of efficient electrocatalysts are also offered.