Enhancing electrocatalytic nitrogen fixation over core-shell P-Sb2S3/MoS2 heterojunction by vacancy and interface modulation.

Electrochemical synthesis of ammonia is a green and sustainable way for nitrogen fixation, but the development of efficient electrocatalysts still faces challenges. The modulation of electronic structure through interface engineering and vacancy engineering is a new approach to enhance the performance of electrocatalysts. In this work, a phosphorus-doped core-shell heterojunction P-Sb2S3/MoS2 was designed and synthesized by combining antimony, which is inert to H+ adsorption, with molybdenum, which has good affinity and reducibility with nitrogen. The synthesis involved both interfacial engineering and vacancy engineering strategies.DFT calculations demonstrate that the formationofSb2S3/MoS2 heterojunction enhances the creation of a built-in electric field, thereby expediting electron flow.Additionally, phosphorus doping induced the formation of abundant sulfur vacancies, significantly enhancing nitrogen adsorption performance in this material.As a result, our designed structure exhibited excellent NRR performance with an ammonia production rate of 41.22 µg·h-1·mg-1cat and a Faraday efficiency of 15.70 %.The unique structural of this catalyst contribute to a more optimal balance between the rate of ammonia production and the Faraday efficiency. The successful preparation of the highly efficient P-Sb2S3/MoS2 heterojunctionsprovidesanew strategyfor catalyst design in electrocatalytic nitrogen reduction.

La doped-Fe2(MoO4)3 with the synergistic effect between Fe2+/Fe3+ cycling and oxygen vacancies enhances the electrocatalytic synthesizing NH3.

The electrocatalytic nitrogen reduction reaction (NRR) is a crucial process in addressing energy shortages and environmental concerns by synthesizing the NH3. However, the difficulty of N2 activation and fewer NRR active sites limit the application of NRR. Therefore, the NRR performance can be improved by rapid electron transport paths to participate in multi-electron reactions and N2 activation. Doping with transition metal element is a viable strategy to provide electrons and electronic channels in the NRR. This study focuses on the synthesis of Fe2(MoO4)3 (FeMo) and x%La-doped FeMo (x = 3, 5, 7, and 10) using the hydrothermal method. La-doping creates electron transport channels Fe2+-O2--Fe3+ and oxygen vacancies, achieving an equal molar ratio of Fe2+/Fe3+. This strategy enables the super-exchange in Fe2+-O2--Fe3+, and then enhances electron transport speed for a rapid hydrogenation reaction. Therefore, the synergistic effect of Fe2+/Fe3+ cycling and oxygen vacancies improves the NRR performance. Notably, 5%La-FeMo demonstrates the superior NRR performance (NH3 yield rate: 29.6 µg h-1 mgcat-1, Faradaic efficiency: 5.8%) at -0.8 V (vs. RHE). This work analyzes the influence of the catalyst electronic environment on the NRR performance based on the effect on different valence states of ions on electron transport.

Au-Added CuS Hollow Spheres to Regulate the Strength and Active Area of N2 Adsorption Sites for Electrochemical NH3 Production.

Ammonia is a chemical compound in considerable global demand and plays a crucial role as an environmentally friendly energy carrier for hydrogen energy storage. The electrochemical nitrogen reduction reaction (eNRR) using copper sulfide catalysts is being extensively studied as an environmentally sustainable approach to the energy-intensive Haber-Bosch process for ammonia production. In this study, we aimed to prepare CuS hollow spheres modified with Au nanoparticles using an antisolvent crystallization-based method to be used as the catalysts for eNRR. During the addition of Au to the CuS catalysts, the nitrogen adsorption strength and surface area of the CuS catalysts are significantly regulated and expanded, leading to a noticeable enhancement in electrocatalytic performance for eNRR. Specifically, the ammonia production rate of 2.4 µmol cm-2 h or jNH3 = 0.2 mA cm-2 is achieved at a selectivity of 52% in neutral aqueous electrolyte, which is more than a 2-fold increase compared to the unmodified CuS catalyst. The findings of this study can contribute to the development of sustainable and environmentally friendly ammonia production in the future.

Diatomic Active Sites Embedded Graphyne as Electrocatalysts for Ammonia Synthesis.

Ammonia (NH3) is a vital chemical compound in industry and agriculture, and the electrochemical nitrogen reduction reaction (eNRR) is considered a promising approach for NH3 synthesis. However, the development of eNRR faces the challenge of high overpotential and low Faradaic efficiency. In this work, graphyne (GY) is anchored by 3d, 4d, and 5d dual transition metal atoms to form diatomic catalysts (DACs) and is roundly investigated as an electrocatalyst for eNRR via density functional theory calculations. Due to the protrusion of anchored metal atoms, the active sites of GY are better exposed compared to other substrates, exhibiting higher activity. Through four-step hierarchical high-throughput screening (ΔG*N2 < 0 eV, ΔG*N2 â†’ *N2H < 0.4 eV, ΔG*NH2 â†’ *NH3 < 0.4 eV, and ΔG*N2 < ΔG*H), the number of selected catalysts in each step is 325, 240, 145, and 20, respectively. Considering a series of factors, including stability, initial potential, and selectivity, 13 kinds of eligible catalysts are identified. Optimal eNRR paths studies show that the best catalyst Mn2@GY features no onset potential. For the three catalysts (Mn2@GY, Ir2@GY, and RhOs@GY), the onset potentials of the most favorable eNRR pathways are -0.07, -0.12, and -0.17 V, respectively. The excellent catalytic activity can be credited to the effective charge transfer and orbital interaction between the active site and adsorbed N2. Our work demonstrates the significance of DACs for ammonia synthesis and provides a paradigm for the study of DACs even for other important reactions.

Two-dimensional Boridene Nanosheets for Efficient Electrochemical Nitrogen Fixation under Ambient Conditions.

The carbon-free electrocatalytic nitrogen reduction reaction (NRR) is an alternative technology to the current Haber-Bosch method, that can be conducted under ambient conditions, and directly converting water and nitrogen (N2) into ammonia (NH3). However, the limited activity and selectivity of NH3 electrosynthesis hinder the practical applications of NRR. In this study, we present a novel type of electrocatalyst called boridene nanosheets enriched with metal vacancies that are specifically designed for efficient electrocatalytic NRR under ambient conditions. Electrochemical testing in a 0.1 M phosphate-buffered saline (PBS) electrolyte demonstrates that boridene exhibits a high Faradaic efficiency of 66.7% for NH3 production at -0.2 V vs. RHE, with a maximum NH3 yield rate of 23.6 µg h-1 mg cat-1 at -0.4 V vs. RHE. Durability tests show that boridene maintains significant stability throughout multiple cycles of NRR. Mechanistic insights are obtained through in situ FTIR spectroscopy, revealing that boridene exhibits a preference for the distal pathway during the process of NRR. These findings highlight the potential of boridene as an efficient and stable catalyst for sustainable NH3 synthesis.

Machine Learning-Enhanced Screening of Single-Atom Alloy Clusters for Nitrogen Reduction Reaction.

The electrochemical nitrogen reduction reaction (eNRR) under ambient conditions is a promising method to generate ammonia (NH3), a crucial precursor for fertilizers and chemicals, without carbon emissions. Single-atom alloy catalysts (SAACs) have reinvigorated catalytic processes due to their high activity, selectivity, and efficient use of active atoms. Here, we employed density functional theory (DFT) calculations integrated with machine learning (ML) to investigate dodecahedral nanocluster-based SAACs for analyzing structure-activity relationships in eNRR. Over 300 nanocluster-based SAACs were screened with all the transition metals as dopants to develop an ML model predicting stability and catalytic performance. Facet sites were identified as optimal doping positions, particularly with late group transition metals showing superior stability and activity. Utilizing DFT+ML, we identified 8 highly suitable SAACs for eNRR. Interestingly, the number of valence d-electrons in dopants proved crucial in screening for eNRR activity. These catalysts exhibited low activity in hydrogen evolution reaction, further enhancing their suitability for eNRR. This successful ML-driven approach accelerates catalyst design and discovery, holding significant practical implications.

Effect of Surface Anions Adsorbed by Rutile TiO2 (001) on Photocatalytic Nitrogen Reduction Reaction: A Density Functional Theory Calculation.

The adsorption of common anions found in water can have a considerable impact on the surface state and optical characteristics of titanium dioxide (TiO2), which has an important impact on the photocatalytic nitrogen reduction reaction (NRR). This work utilizes density functional theory (DFT) computations to examine the electronic and optical characteristics of the TiO2 (001) surface under various anion adsorptions in order to clarify their influence on the photocatalytic NRR of TiO2. The modifications in the structure, optical, and electronic properties of TiO2 before and after anion adsorption are investigated. In addition, the routes of Gibbs free energy for the NRR are also evaluated. The results indicate that the adsorption of anions modifies the surface characteristics of TiO2 to a certain degree, hence impacting the separating and recombining charge carriers by affecting the energy gap of TiO2. More importantly, the adsorption of anions can increase the energy barriers for the NRR, thereby exerting a detrimental effect on its photocatalytic activity. These findings provide a valuable theoretical contribution to understanding the photocatalytic reaction process of TiO2 and its potential application of NRR in the actual complex water phase.

Designing C9N10 Anchored Single Mo Atom as an Efficient Electrocatalyst for Nitrogen Fixation.

Electrochemical nitrogen reduction reaction (NRR) is a promising route for realizing green and sustainable ammonia synthesis under ambient conditions. However, one of the major challenges of currently available Single-atom catalysts (SACs) is poor catalytic activity and low catalytic selectivity, which is far away from the requirements of industrial applications. Herein, first-principle calculations within the density functional theory were performed to evaluate the feasibility of a single Mo atom anchored on a g-C9N10 monolayer (Mo@g-C9N10) as NRR electrocatalysts. The results demonstrated that the gas phase N2 molecule can be sufficiently activated on Mo@g-C9N10, and N2 reduction dominantly occurs on the active Mo atom via the preferred enzymatic mechanism, with a low limiting potential of -0.48 V. In addition, Mo@g-C9N10 possesses a good prohibition ability for the competitive hydrogen evolution reaction. More impressively, good electronic conductivity and high electron transport efficiency endow Mo SACs with excellent activity for electrocatalytic N2 reduction. This theoretical research not only accelerates the development of NRR electrocatalysts but also increases our insights into optimizing the catalytic performance of SACs.

Plasmon-Promoted Interatomic Hot Carriers Regulation Enhanced Electrocatalytic Nitrogen Reduction Reaction.

Utilizing hot carriers for efficient plasmon-mediated chemical reactions (PMCRs) to convert solar energy into secondary energy is one of the most feasible solutions to the global environmental and energy crisis. Finding a plasmonic heterogeneous nanostructure with a more efficient and reasonable hot carrier transport path without affecting the intrinsic plasmonic properties is still a major challenge that urgently needs to be solved in this field. Herein, the mechanism by which plasmon-promoted interatomic hot electron redistribution on the surface of Au3Cu alloy nanoparticles promotes the electrocatalytic nitrogen reduction reaction (ENRR) is successfully clarified. The localized surface plasmon resonance (LSPR) effect can boost the transfer of plasmon hot electrons from Au atoms to Cu atoms, trigger the interatomic electron regulation of Au3Cu alloy nanoparticles, enhance the desorption of ammonia molecules, and increase the ammonia yield by approximately 93.9 %. This work provides an important reference for rationally designing and utilizing the LSPR effect to efficiently regulate the distribution and mechanism of plasmon hot carriers on the surface of heterogeneous alloy nanostructures.

Electron Sponge Effect by Dynamic-Regulated Electron Self-Flow toward Coupled Electrochemical Ammonia Synthesis.

A dynamic-regulated Pd-Fe-N electrocatalyst was effectively constructed with electron-donating and back-donating effects, which serves as an efficient engineering strategy to optimize the electrocatalytic activity. The designed PdFe3/FeN features a comprehensive electrocatalytic performance toward the nitrogen reduction reaction (NRR, yield rate of 29.94 µg h-1 mgcat-1 and FE of 38.43% at -0.2 V vs RHE) and oxygen evolution reaction (OER, 308 mV at 100 mA cm-2). Combining in situ ATR-FTIR, XAS, and DFT results, the role of the interstitial-N-dopant-induced electron sponge effect has been significantly elucidated in strengthening the electrocatalytic NRR process. Specifically, the introduction of a N dopant, an electron acceptor, initiates the generation of robust Lewis-acidic Fe sites, facilitating free N2 capture and bonding. Simultaneously, after NH3 adsorption, the N dopant can back-donate electrons to Fe sites, strengthening the NH3 deportation through weakening the Lewis acidity of Fe centers. Besides, the electron-deficient Fe sites contribute to the reconstruction of FeOOH, the real active species during the OER, which accelerates the four-electron reaction kinetics. This research offers a perspective on electrocatalyst design, potentially facilitating the evolution of advanced material engineering for efficient electrocatalytic synthesis and energy storage.

Spin Manipulation of Co sites in Co9S8/Nb2CTx Mott-Schottky Heterojunction for Boosting the Electrocatalytic Nitrogen Reduction Reaction.

Regulating the adsorption of an intermediate on an electrocatalyst by manipulating the electron spin state of the transition metal is of great significance for promoting the activation of inert nitrogen molecules (N2) during the electrocatalytic nitrogen reduction reaction (eNRR). However, achieving this remains challenging. Herein, a novel 2D/2D Mott-Schottky heterojunction, Co9S8/Nb2CTx-P, is developed as an eNRR catalyst. This is achieved through the in situ growth of cobalt sulfide (Co9S8) nanosheets over a Nb2CTx MXene using a solution plasma modification method. Transformation of the Co spin state from low (t2g 6eg 1) to high (t2g 5eg 2) is achieved by adjusting the interface electronic structure and sulfur vacancy of Co9S8/Nb2CTx-P. The adsorption ability of N2 is optimized through high spin Co(II) with more unpaired electrons, significantly accelerating the *N2→*NNH kinetic process. The Co9S8/Nb2CTx-P exhibits a high NH3 yield of 62.62 µg h-1 mgcat. -1 and a Faradaic efficiency (FE) of 30.33% at -0.40 V versus the reversible hydrogen electrode (RHE) in 0.1 m HCl. Additionally, it achieves an NH3 yield of 41.47 µg h-1 mgcat. -1 and FE of 23.19% at -0.60 V versus RHE in 0.1 m Na2SO4. This work demonstrates a promising strategy for constructing heterojunction electrocatalysts for efficient eNRR.

Designing V single atom embedded carbon moiety for the electrocatalytic nitrogen reduction reaction by first principles study.

Development of an efficient electrocatalyst for the nitrogen reduction reaction (NRR) to serve as an sustainable alternative to the Haber-Bosch process has proven highly challenging. Single atom catalysts (SACs), which have the maximum atom utilization efficiency, are among the most promising candidates. Single atoms can be incorporated to a catalytic system by doping or substitution or by attaching a molecular coordination complex to a substrate and the different insertion modes allow the chemical environment to be varied. We have used DFT to investigate vanadium SACS for NRR activity with a focus on varying the coordination environment of the V atom. Phthalocyanine, porphyrin and graphene like coordination environments with varying N-coordination have been studied. Vanadium phthalocyanine (VphN4) is the most promising of the investigated systems. It features a high selectivity relative the HER reaction and relatively strong binding of N2 relatively H, which prevents poisoning of the surface by hydrogen. VphN4 also has the lowest overpotential among the studied systems. The electrocatalytic properties of VphN4 deposited as a monolayer on the Ag (111) surface have been investigated. This system, which already has been prepared, shows promising properties for use as a catalytic electrode for the NRR reaction.

Main-Group Metal-Nonmetal Dynamic Proton Bridges Enhance Ammonia Electrosynthesis.

The electrochemical nitrogen reduction reaction (eNRR) is a crucial process for the sustainable production of ammonia (NH3) for energy and agriculture applications. However, the reaction's efficiency is highly dependent on the activation of the inert N≡N bond, which is hindered by the electron back-donation to the π* orbitals of the N≡N bond, resulting in low eNRR capacity. Herein, we report a main-group metal-nonmetal (O-In-S) eNRR catalyst featuring a dynamic proton bridge, with In-S serving as the polarization pair and O functioning as the dynamic electron pool. In situ spectroscopic analysis and theoretical calculations reveal that the In-S polarization pair acts as asymmetric dual-sites, polarizing the N≡N bond by concurrently back-donating electrons to both the πx* and πy* orbitals of N2, thereby overcoming the significant band gap limitations, while inhibiting the competitive hydrogen evolution reaction. Meanwhile, the O dynamic electron pool acts as a "repository" for electron storage and donation to the In-S polarization pair. As a result, the O-In-S dynamic proton bridge exhibits exceptional NH3 yield rates and Faradaic efficiencies (FEs) across a wide potential window of 0.3 V, with an optimal NH3 yield rate of 80.07±4.25 µg h-1 mg-1 and an FE of 38.01±2.02 %, outperforming most previously reported catalysts.

In Situ Characterization Techniques for Electrochemical Nitrogen Reduction Reaction.

The electrochemical reduction of nitrogen to produce ammonia is pivotal in modern society due to its environmental friendliness and the substantial influence that ammonia has on food, chemicals, and energy. However, the current electrochemical nitrogen reduction reaction (NRR) mechanism is still imperfect, which seriously impedes the development of NRR. In situ characterization techniques offer insight into the alterations taking place at the electrode/electrolyte interface throughout the NRR process, thereby helping us to explore the NRR mechanism in-depth and ultimately promote the development of efficient catalytic systems for NRR. Herein, we introduce the popular theories and mechanisms of the electrochemical NRR and provide an extensive overview on the application of various in situ characterization approaches for on-site detection of reaction intermediates and catalyst transformations during electrocatalytic NRR processes, including different optical techniques, X-ray-based techniques, electron microscopy, and scanning probe microscopy. Finally, some major challenges and future directions of these in situ techniques are proposed.

In Situ Fe/Co/B Codoped MoS2 Ultrathin Nanosheets Enable Efficient Electrocatalytic Nitrogen Reduction.

The development of sustainable and effective electrochemical nitrogen fixation catalysts is crucial for the mitigation of the terrible energy consumption resulting from the Haber-Bosch process. Molybdenum disulfide (MoS2) exhibits promise toward nitrogen reduction reaction (NRR) on account of its similar structure to natural nitrogenases MoFe-co but still undergoes serious challenges with unsatisfactory catalytic performance resulted from limited active sites, conductivity, and selectivity. In this work, Fe/Co/B codoped MoS2 ultrathin nanosheets are synthesized and verified as excellent NRR catalysts with high activity, selectivity, and durability. The FeCoB-MoS2 demonstrates a high ammonia yield of 36.99 µg h-1 mgcat-1 at -0.15 V vs RHE and Faraday efficiency (FE) of 30.65% at -0.10 V vs RHE in 0.1 M HCl. The experimental results and the density functional theory (DFT) calculations emphasize that codoping of Fe, Co, and B into MoS2 synergistically enhances its conductivity and optimizes the electronic structure of the catalyst, which significantly improves the electrocatalytic ammonia synthesis performance. This work broadens the potential and enlightens the strategy for designing efficient electrocatalysts in the NRR field.

Main-Group Elements Enhance Electrochemical Nitrogen Reduction Reaction of Vanadium-Based Single Atom Catalysts Through d-p Orbital Hybridization.

Developing active sites with flexibility and diversity is crucial for single atom catalysts (SACs) towards sustainable nitrogen fixation at ambient conditions. Herein, the effects of doping main group metal elements (MGM) on the stability, catalytic activity, and selectivity of vanadium-based SACs is systematically investigated based on density functional theory calculations. It is found that the catalytic activity of V site can be significantly enhanced by the synergistic effect between MGM and vanadium atoms. More importantly, a volcano curve between the catalytic activity and the adsorption free energy of NNH* can be established, in which V-Pb dimer embedded on N-coordinated graphene (VPb-NG) exhibits optimal NRR activity due to its location at the top of volcano. Further analysis of electronic structures reveals that the unoccupancy ratio (eg/t2g) of V site is dramatically increased by the strong d-p orbital hybridization between V and Pb atoms, subsequently, N2 is activated to a larger extent. These interesting findings may provide a new path for designing active sites in SACs with excellent performance.

Modulating the Leverage Relationship in Nitrogen Fixation Through Hydrogen-Bond-Regulated Proton Transfer.

In the electrochemical nitrogen reduction reaction (NRR), a leverage relationship exists between NH3-producing activity and selectivity because of the competing hydrogen evolution reaction (HER), which means that high activity with strong protons adsorption causes low product selectivity. Herein, we design a novel metal-organic hydrogen bonding framework (MOHBF) material to modulate this leverage relationship by a hydrogen-bond-regulated proton transfer pathway. The MOHBF material was composited with reduced graphene oxide (rGO) to form a Ni-N2O2 molecular catalyst (Ni-N2O2/rGO). The unique structure of O atoms in Ni-O-C and N-O-H could form hydrogen bonds with H2O molecules to interfere with protons being directly adsorbed onto Ni active sites, thus regulating the proton transfer mechanism and slowing the HER kinetics, thereby modulating the leverage relationship. Moreover, this catalyst has abundant Ni-single-atom sites enriched with Ni-N/O coordination, conducive to the adsorption and activation of N2. The Ni-N2O2/rGO exhibits simultaneously enhanced activity and selectivity of NH3 production with a maximum NH3 yield rate of 209.7 µg h-1 mgcat. -1 and a Faradaic efficiency of 45.7 %, outperforming other reported single-atom NRR catalysts.

Machine learning-driven shortening the screening process towards high-performance nitrogen reduction reaction electrocatalysts with four-step screening strategy.

The urgent need to prepare clean energy by environmentally friendly and efficient methods, which has led to widespread attention on electrocatalytic nitrogen reduction reaction (NRR) for ammonia production. At present, single atom catalytic nitrogen reduction has become the earliest promising method for industrial production due to its high atomic utilization rate, high selectivity, high controllability, and high stability. However, how to quickly screen catalysts with high catalytic efficiency and selectivity in single-atom catalysts (SACs) remains a challenge. Herein, the 29 SACs are constructed from C6N2 nanosheets doped with transition metals (TM@C6N2), which are analyzed for stability, adsorption performance, NRR catalytic activity, electronic properties, and competitiveness using first-principles calculations. The results show that Mo@C6N2 and Re@C6N2 exhibit the most outstanding catalytic performances, with limiting potentials (UL) of -0.29 and -0.31 V, respectively, in the solvent model. Machine learning is used to derive descriptors from the intrinsic features to predict the free energy changes for the potential-determining step. The importance of features is calculated, with the first ionisation energy (IE1) being the most significant influencing factor. Based on the guidance of machine learning and considering that IE1 is related to the ability of metal atoms to donate electrons, a four-step screening strategy using the Integrated Crystal Orbital Hamilton Populations (ICOHP) to screen catalysts instead of the traditional five-step screening not only improves the screening efficiency but also obtains completely consistent screening results. This work presents a new approach to predicting the catalytic performance of SACs and provides new insights into the influence of intrinsic properties on catalytic activity.

Electrocatalytic Dinitrogen Reduction to Ammonia Using Easily Reducible N-Fused Cobalt Porphyrins.

Single-site molecular electrocatalysts, especially those that perform catalytic conversion of N2 to NH3 under mild conditions, are highly desirable to derive fundamental structure-activity relations and as potential alternatives to the current energy-consuming Haber-Bosch ammonia production process. Combining theoretical calculations with experimental evidence, it has been shown that easily reducible cobalt porphyrins catalyze the six-electron, six-proton reduction of dinitrogen to NH3 at neutral pH and under ambient conditions. Two easily reducible N-fused cobalt porphyrins - CoNHF and CoNHF(Br)2 - reveal NRR activity with Faradic efficiencies between 6-7.5 % with ammonia yield rates of 300-340 µmol g-1 h-1. Contrary to this, much harder-to-reduce N-fused porphyrins - CoNHF(Ph)2 and CoNHF(PE)2 - reveal no NRR activity. The present study highlights the significance of tuning the redox and structural properties of single-site NRR electrocatalysts for improved NRR activity under mild conditions.

Density Functional Theory Study of Triple Transition Metal Cluster Anchored on the C2N Monolayer for Nitrogen Reduction Reactions.

The electrochemical nitrogen reduction reaction (NRR) is an attractive pathway for producing ammonia under ambient conditions. The development of efficient catalysts for nitrogen fixation in electrochemical NRRs has become increasingly important, but it remains challenging due to the need to address the issues of activity and selectivity. Herein, using density functional theory (DFT), we explore ten kinds of triple transition metal atoms (M3 = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) anchored on the C2N monolayer (M3-C2N) as NRR electrocatalysts. The negative binding energies of M3 clusters on C2N mean that the triple transition metal clusters can be stably anchored on the N6 cavity of the C2N structure. As the first step of the NRR, the adsorption configurations of N2 show that the N2 on M3-C2N catalysts can be stably adsorbed in a side-on mode, except for Zn3-C2N. Moreover, the extended N-N bond length and electronic structure indicate that the N2 molecule has been fully activated on the M3-C2N surface. The results of limiting potential screen out the four M3-C2N catalysts (Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N) that have a superior electrochemical NRR performance, and the corresponding values are -0.61 V, -0.67 V, -0.63 V, and -0.66 V, respectively, which are smaller than those on Ru(0001). In addition, the detailed NRR mechanism studied shows that the alternating and enzymatic mechanisms of association pathways on Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N are more energetically favorable. In the end, the catalytic selectivity for NRR on M3-C2N is investigated through the performance of a hydrogen evolution reaction (HER) on them. We find that Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N catalysts possess a high catalytic activity for NRR and exhibit a strong capability of suppressing the competitive HER. Our findings provide a new strategy for designing NRR catalysts with high catalytic activity and selectivity.