N2 Reduction Reaction Activity Research Articles

Tuning Surface Potential Polarization to Enhance N2 Affinity for Ammonia Electrosynthesis.

Electrocatalytic N2 reduction reaction (NRR) to synthesize ammonia is a sustainable reaction that is expected to replace Haber Bosch process. Laminated Bi2WO6 has great potential as an NRR electrocatalyst, however, the effective activity requires that the inert substrate is fully activated. Here, for the first time, success is achieved in activating the Bi2WO6 basal planes with NRR activity through Ti doping. The introduction of Ti successfully tunes the surface potential distribution and enhances the N2 adsorption. The subsequently strong hybrid coupling of d(Ti)-p(N) orbitals fills the electronic state of N2 antibonding molecular orbital, which greatly weakens the bonding strength of N≡N bonds. Further, in situ synchrotron radiation-based Fourier transform infrared(SR-FTIR) spectrum and theoretical calculations show that surface potential polarization enhances the adsorption of HNN* by Bi-Ti dual-metal sites, which is beneficial for the subsequent activation hydrogenation process. The Ti-Bi2WO6 nanosheets achieve 11.44% Faradaic efficiency (-0.2V vs. RHE), a NH3 yield rate of 23.14µgmg-1h-1 (15N calibration), and satisfactory stability in 0.1M HCl environment. The mutual assistance of theory and experiment can help understand and develop of excellent two-dimensional (2D) materials for the NRR.

Bi2WO6 Incorporation of g‐C3N4 to Enhance the Photocatalytic N2 Reduction Reaction and Antibiotic Pollutants Removal

Synthesis of ammonia from photocatalytic N2 reduction is challenging due to the fast recombination of electron–hole pairs and the low selectivity of N2 on catalysts. This can be addressed by creating heterojunctions to separate the photogenerated carriers adequately. In this regard, BW/g‐C3N4 is synthesized and the weight percentage of g‐C3N4 is varied. The best photocatalytic activity for N2 reduction reaction (N2RR) is achieved with a ratio of BW/gC3N4 in 3.5:2 ratio, deemed to be the optimized heterojunction. N2‐temperature programmed desorption analysis shows outstanding chemisorption of N2 adsorbed on the BW/g‐C3N4 surface compared to pristine g‐C3N4 and BW. Additionally, forming a heterojunction enhances the charge transfer process and well‐separated electron–hole pairs, significantly boosting the water oxidation process on the catalytic surface. Photoelectrochemical analysis reveals that BW/g‐C3N4 exhibits the shortest hole relaxation lifetime and higher current density than its pristine counterparts. The robust contact between g‐C3N4 and BW reduces the work function of BW/g‐C3N4 based on ultraviolet photoelectron spectroscopy data. Ammonia production with the optimized BW/gC3N4‐3.5:2 is 5.3 and 2.1 times higher than pure g‐C3N4 and Bi2WO6, respectively. Meanwhile, BW/g‐C3N4 demonstrates excellent photocatalytic activity toward antibiotic pollutant degradation as well. After 150 min of visible light irradiation, the removal of 94% ciprofloxacin (CIP) is observed. Finally, a possible mechanism is proposed for photocatalytic N2RR and CIP degradation.

Nitrogen-vacancy-rich molybdenum nitride nanosheets as highly efficient electrocatalysts for nitrogen reduction reaction.

The development of low-cost earth-abundant electrocatalysts to produce ammonia (NH3) with high efficiency for the nitrogen (N2) reduction reaction (NRR) remains challenging. Herein, we propose the development of highly efficient ultrathin nitrogen-vacancy-rich molybdenum nitride nanosheets (MoN-NV) for NRR using basic electrolytes under ambient conditions. In 0.1 M KOH, this catalyst attained a high faradaic efficiency (FE) of ∼14% with an NH3 yield of 22.5 μg h-1 mg-1cat at -0.3 V vs. a reversible hydrogen electrode under ambient conditions. The characterization results and electrochemical studies disclosed that nitrogen vacancies in the MoN-NV nanosheets played a critical role in the enhanced electrocatalytic activity for NRR. Furthermore, the recycling tests confirmed the stability of the catalyst during NRR electrolysis.

Tuning Coordination Structures of Zn Sites Through Symmetry-Breaking Accelerates Electrocatalysis.

Manipulating the coordination environment of individual active sites in a precise manner remains an important challenge in electrocatalytic reactions. Herein, inspired by theoretical predictions, a facile procedure to synthesize a series of symmetry-breaking zinc metal-organic framework (Zn-MOF) catalysts with well-defined structures is presented. Benefiting from the optimized coordination microenvironment regulated by symmetry-breaking, Zn-N2 S2 -MOF exhibits the best performance of nitrogen (N2 ) reduction reaction (NRR) with NH3 yield rate of 25.07±1.57µgh-1 cm-2 and Faradaic efficiency of 44.57±2.79% compared with reported Zn-based NRR catalysts. X-ray absorption near-edge structure shows that the symmetry-breaking distorts the coordination environment and modulates the delocalized electrons around the Zn sites, which favors the formation of unpaired low-valence Znδ+ , thereby facilitating the adsorption/activation of N2 . Theoretical calculations elucidate that low-valence Znδ+ in Zn-N2 S2 -MOF can effectively lower the energy barrier of potential determining step, promoting the kinetics and boosting the NRR activity. This work highlights the relationship between the precise coordination environment of metal sites and the catalytic activity, which offers insightful guidance for rationally designing high-efficiency electrocatalysts.

Unveiling the competitive behavior by the orientated regulation of S-vacancy over MoS2 for highly effective N2 fixation

The electrochemical N2 reduction reaction (NRR) renders great potential for sustainable ammonia generation but still suffers from serious challenges, which limit the effective enhancement of catalytic performances. Herein, we skillfully utilize the asynchronous NRR and hydrogen evolution reaction (HER) activities as a function of S-vacancy (Vs) concentrations to enhance the NRR activity but sacrifice the HER activity, thus achieving the tradeoff between activity and selectivity towards the NRR. Inspired by the theoretical guidance, the optimized catalyst (FL-MoS2-20) with a suitable Vs concentration (16.30 %) renders a high NH3 yield rate of 92.95 ± 2.10 µg h−1 mg−1 and a Faradic efficiency (FE) of 20.80 ± 0.18 %, exceeding virtually all previously published MoS2-based NRR catalysts and the overwhelming majority of state-of-the-art NRR catalysts. This work broadens the potential of vacancy engineering to manage the competitive reaction on a single active site and enlightens the catalyst design in the NRR field and beyond.

Impurity tuning for enhanced electrocatalytic reduction of N2 to NH3 over Fe/Co Co-doped MoS2 nanosheets

The electrochemical N2 reduction reaction (NRR) has attracted much attention for its use in the production of fertilizers and other chemicals. Herein, we demonstrate that the NRR can be enhanced when using Fe/Co co-doped MoS2 (FeCo–MoS2) nanosheets as the electrocatalyst. At the optimal doping concentration, the FeCo–MoS2 nanosheets provided a NH3 yield rate of 3.27 μg/h/cm2 at −0.55 V [vs reversible hydrogen electrode (RHE)], a value superior to those of undoped MoS2, Fe-doped MoS2, and Co-doped MoS2 samples by 191, 176, and 116%, respectively. Moreover, the Faradaic efficiency of 6.28% at −0.35 V (vs RHE) exceeded those of the undoped MoS2, Fe-doped MoS2, and Co-doped MoS2 samples by 217, 186, and 132%, respectively. Density functional theory calculations revealed that the preferred reaction mediated by the FeCo–MoS2 electrocatalyst followed a distal pathway, with its potential-determining step having an energy barrier (0.54 eV) lower than that of undoped MoS2 (1.13 eV), suggesting that the FeCo–MoS2 nanosheets possessed superior electrocatalytic activity. We conclude that Fe and Co are efficient dopants for boosting the NRR activity of MoS2 catalysts.

Transition metal doped and strain engineered VS−MoS2 as electrocatalysts for N2 electroreduction: A DFT study

S vacancy activated MoS2 (VS−MoS2) materials are greatly attractive as electrocatalysts in electrocatalytic N2 reduction reaction (NRR). Herein, we investigate the electrocatalytic NRR performance of transition metal (Cr, Mn, V, W) doped and strain engineered VS−MoS2 using first-principles calculations. For all the designed MoS2s, VS is easy to form due to the small defect formation energy (≤3.48 eV) and determined as active site for N2 adsorption and electrocatalytic NRR. Calculation results show that doping and strain regulate the electrocatalytic activity of VS−MoS2 by altering its electronic properties. When strain is absent, Cr-, Mn-, and V-VS−MoS2 exhibit better electrocatalytic NRR activity than undoped VS−MoS2, while W-VS−MoS2 shows slightly worse activity. However, the above situation changes with applying strain. Moreover, the catalytic activity of all the catalysts firstly decreases and then increases with increasing strain. Further comprehensive considering limiting potential (UL) and Faraday efficiency (FE), Cr-VS−MoS2 under 7 % strain is identified as the best NRR electrocatalyst with both excellent activity (UL = -0.18 V) and high selectivity (FE = 99.44 %). In addition, 5 % and 6 % strained Mn-VS−MoS2 are also good electrocatalysts for NRR with low UL and (-0.45 V and -0.23 V, respectively) and substantial FE (37.69 % and 19.29 %, respectively). Therefore, the electrocatalytic NRR performance of VS−MoS2 could be optimized through transition metal doping and strain engineering. Relevant experimental explores will be encouraged based on our theoretical findings.

Insights of active sites separation mechanism for highly efficient electrocatalytic N2 reduction to ammonia over glucose-induced metallic MoS2

Substituting the Haber-Bosch process with electrocatalytic N2 reduction reaction (NRR) is expected to be realized by optimizing the active sites to boost the sluggish N2 adsorption and the hydrogenation process without interference by the thermodynamically favored hydrogen evolution reaction (HER). Herein, a phase engineering strategy for MoS2 toward NRR is reported. The 1T phase are found to enhance the NRR activity with strong N2 adsorption. Then, the active site separation can weaken the competitive adsorption between H+ and N2 reactant on the Mo-edge, improving the NRR selectivity. More importantly, the HER selective basal plane can serve as an H-provider to further accelerate the hydrogenation process of NRR. The optimal MoS2/C-0.4 possesses a high ammonia yield rate of 80.38 μg h–1 mg–1cat. and Faradaic efficiency (FE) of 23.76%, outperforming almost all MoS2-based electrocatalysts and beyond. This work sheds light on synchronizing the catalytic activity and selectivity for catalytic reactions.

Cooperative electrocatalytic N2 reduction based on WS2-covered Co9S8 hexagonal heterostructures derived from ZIF-67@POMs

Electrochemical N2 reduction reaction (NRR) to produce NH3 at ambient conditions is a promising route to replace the energy-intensive Haber–Bosch process, but electrochemical NRR with satisfied efficiency remains challenging. Therefore, a number of efforts have been committed to develop high-performance NRR electrocatalysts for highly efficient NH3 synthesis. Herein, Co9S8 nanosheets with a WS2 outer layer (Co9S8@WS2) are designed and prepared from ZIF-67@polyoxometalates (polyoxometalates , H3PW12O40·xH2O) and used for NRR at ambient temperature and pressure. The successful introduction of S-vacancies can adjust the electronic structure of the material by forming a electron-deficient environment, can make N2 molecules easily adsorbed and activated on the W active site of the catalyst surface, and thus, can promote the electrocatalytic NRR activity of the catalyst. In 0.1 M KOH, the optimized Co9S8@WS2-900 exhibits enhanced Faradaic efficiency (46.81%) and good NH3 yield (50.25 μg h−1 mgcat.−1) at −0.4 V vs. a reversible hydrogen electrode, exceeding many recently reported cobalt- or tungsten-based materials. The superior electrocatalytic activity is attributed to the unique composite structures and synergistic effect of electronic couplings between Co9S8 and sulfur-rich vacancies WS2. A density functional theory calculation indicates that the inert N2 can be activated by bare W atoms on the rim of the S-vacancies in Co9S8@WS2. The protonation of N2 to form N–NH∗ species is the potential-limiting step (ΔG = 1.05 eV). Therefore, the unique bimetallic sulfide clad architecture and rich S vacancies of Co9S8@WS2 provide the reference and inspiration for better designing of high-efficiency nitrogen-fixing catalysts.

Heterogeneous metal trimer catalysts on Mo2TiC2O2 MXene for highly active N2 conversion to NH3

Activating the inert basal plane of functional-group-terminated MXenes is highly desirable for non-noble metal MXenes applied for the N2 reduction reaction (NRR) to value-added ammonia (NH3), but remains a significant challenge. Herein, we report the coupled interactions and catalytic mechanism of the supported trimeric metal M3 single-cluster catalysts (SCCs) on oxygen-vacancy-rich Mo2TiC2O2 (VO−Mo2TiC2O2) MXene materials for catalyzing this difficult reaction via spin-polarized density functional theory (DFT) calculations. Energy and electronic property analysis showed that the robust structural stability of the M3/VO−Mo2TiC2O2 catalysts stemmed from the vacancy defects, electronegativity difference, and significant charge redistribution. Based on the unique bidirectional electron transfer activation mechanism, the N2 adsorption strength can be well represented by a simple descriptor of the valence electrons in the d orbitals of M3 trimers. Remarkably, these confined Rh3, Ru3, Ni3 and Co3 SCCs on VO−Mo2TiC2O2 were capable of providing superior electrocatalytic activity and selectivity toward the NRR with ultra-low limiting potentials of −0.23, −0.32, −0.42 and −0.44 V, respectively. Finally, a mechanistic investigation illustrated that the valence electrons, charge transfer, and d-band center of the M3 active sites could collectively act as good descriptors to correlate the structure and NRR activity.

Boosting Electroreduction Kinetics of Nitrogen to Ammonia via Atomically Dispersed Sn Protuberance.

Atomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X-ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3 ) of 28.3 μg h-1 mgcat -1 (7447 μg h-1 mgSn -1 ) at -0.3 V. Furthermore, the enhanced N2 Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation.

Boosting Electroreduction Kinetics of Nitrogen to Ammonia via Atomically Dispersed Sn Protuberance

AbstractAtomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X‐ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3) of 28.3 μg h−1 mgcat−1 (7447 μg h−1 mgSn−1) at −0.3 V. Furthermore, the enhanced N2Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation.

Dual-phase B-doped FeCoNiCuPd high-entropy alloys for nitrogen electroreduction to ammonia.

Dual-phase B-doped FeCoNiCuPd high-entropy alloy (DP-B-HEA) nanoparticles were synthesized via a strategy involving thermodynamically driven solid-phase diffusion. The DP-B-HEA/CNFs showed an outstanding electrochemical N2 reduction reaction (NRR) performance with an ammonia yield of 24.8 μmol h-1 cm-2 and NH3 faradaic efficiency (FE) of 39.2%. The optimized electronic structures of the HEA resulting from B doping led to the enhanced NRR activity and selectivity.

Controlled etching to immobilize highly dispersed Fe in MXene for electrochemical ammonia production

AbstractElectrocatalytic N2 reduction reaction (NRR), as an efficient and low‐carbon NH3 production method, is highly desired to replace the traditional Haber–Bosch process under ambient conditions. Nevertheless, its industrial application remains hampered by the low Faradaic efficiency (FE) and an inferior ammonia yield mainly owing to the sluggish kinetics and the competing hydrogen evolution reaction (HER). Here, highly dispersed Fe immobilized in Ti3C2Tx MXene (HD‐Fe‐MXene) is for the first time developed by a controlled etching strategy to act as an efficient electrochemical ammonia production catalyst. In this process, the Al phase of MAX is firstly replaced by Fe through Lewis‐acidic‐melt selective etching, then the HD‐Fe‐MXene is obtained by etching with an HCl solution. The as‐prepared HD‐Fe‐MXene delivers outstanding NRR activity with an FE of 21.8% at −0.1 V versus reversible hydrogen electrode (RHE) and a favorable NH3 yield of 18.25 µg h−1 mg−1 (−0.25 V vs. RHE) in 0.1 M Na2SO4 electrolyte. Notably, HD‐Fe‐MXene exhibits superior stability during the six times recycling tests and the 24 h chronoamperometric test. This excellent NRR electrocatalytic activity is mainly ascribed to the highly dispersed Fe immobilized in the fluorine‐free Ti3C2Tx MXene, which inhibits Fe centers from aggregation for providing abundant active sites for NRR. Moreover, the two‐dimensional structure and the fluorine‐free property of Ti3C2Tx MXene benefit to provide abundant sites for N2 adsorption and promote the electron transfer thus boosting the NRR process. This study delivers a feasible strategy for adding transition metal into the MXene phase to enhance the electrocatalytic activity of MXene‐based catalysts for nitrogen electroreduction to ammonia.

Rational design of highly efficient electrocatalytic single-atom catalysts for nitrogen reduction on nitrogen-doped graphene and g-C2N supports

Electrochemical N2 reduction reaction (NRR) is a very attractive route for ammonia production under ambient conditions. It is a challenging issue to develop efficient electrocatalysts in NRR process. Herein, we designed a series of NRR single-atom catalysts (SACs), namely, transition metal single-atom anchored on nitrogen-doped porous graphene with six-fold N6 cavity (TM@N6-G). Based on spin-polarized density functional theory (DFT) calculations, the stability and catalytic performance of TM@N6-G SACs were systemically investigated. Six promising catalysts (Nb, Mo, Tc, Ta, W, and Re@N6-G) are selected from 14 candidates by screening the free energy changes of the first and last electric chemical steps. Detailed NRR mechanism studies show that the six SACs have superior electrochemical NRR performance, especially W@N6-G, reaching low limiting potentials of −0.23 V. Furthermore, we extend the present study to another kind of graphitic carbon nitrides, g-C2N, which has a similar N6 cavity. Our calculations show that five TM@g-C2N SACs have good stability and high activity and selectivity for NRR. In addition, ΔG*NNH, dN-N, and ICOHP can be used as descriptors to understand the origin of NRR catalytic activity of these two kinds of catalysts. The present work may provide valuable clues for exploring promising and efficient NRR electrochemical catalysts.

MXene Quantum Dots/Copper Nanocomposites for Synergistically Enhanced N2 Electroreduction

Electrocatalytic N2 reduction reaction (NRR) represents an appealing solution for sustainable ammonia production, whereas exploring high‐efficiency NRR catalysts is highly desired but extremely challenging. Herein, we combine Ti3C2Tx‐MXene quantum dots (MQDs) with porous Cu nanosheets to design a novel heterostructured MQDs/Cu as an effective and durable NRR catalyst. Impressively, MQDs/Cu showed a synergistically enhanced NRR activity with an NH3 yield of 78.5 μg h−1 mg−1 (−0.5 V) and a Faradaic efficiency of 21.3% (−0.4 V), far superior to pure MQDs and Cu, and outperforming the majority of the state‐of‐the‐art NRR catalysts. Density function theory computations demonstrated that the synergy of MQDs and Cu enabled the creation of interfacial Cu‐Ti dimer as dual‐active‐centers to strongly activate the absorbed N2 and promote the *N2H formation, consequently resulting in the much reduced energy barriers and greatly enhanced NRR performance.

Engineering Reductive Iron on a Layered Double Hydroxide Electrocatalyst for Facilitating Nitrogen Reduction Reaction

AbstractAmmonia is an indispensable chemical, of which the industrial production is still dominated by Haber‐Bosch process operated at harsh conditions. The ecofriendly electrocatalytic N2 reduction reaction (NRR) emerges as an alternative, however, such technique currently suffers from tough dynamics on account of difficulties in the adsorption or protonation of N2 on catalysts. To eliminate the obstacle, a simple and valid strategy of ferrous iron replacing copper is proposed to regulate the electronic structure of layered double hydroxide (LDH) for boosting the NRR activity. Thanks to the ferrous iron, the Fe(II)Cu(II)Fe(III)‐LDH catalyst attains a NH3 yield rate of 33.1 ± 2.5 µg h−1 mgcat.−1 and a desirable Faradaic efficiency (FE) of 21.7 ± 1.8% in a neutral electrolyte of 0.1 m Na2SO4, outclassing the Cu(II)Fe(III)‐LDH catalyst without Fe(II). The introduction of ferrous iron can adjust the d‐band center position to improve the N2 adsorption and can reduce the energy barrier of the potential determining step (PDS) to facilitate the NRR process. This work provides a new insight on engineering efficient electrocatalysts for nitrogen fixation under ambient conditions.

Vacancy engineering of oxidized Nb2CTx MXenes for a biased nitrogen fixation

The artificial nitrogen (N2) reduction reaction (NRR) via electrocatalysis is a newly developed methodology to produce ammonia (NH3) at ambient conditions, but faces the challenges in N2 activation and poor reaction selectivity. Herein, Nb-based MXenes are developed to remarkably enhance the NRR activity through the engineering of the stretched 3D structure and oxygen vacancies (VO). The theoretical studies indicate that N2 could be initially adsorbed on VO with an end-on configuration, and the potential determining step might be the first hydrogenation step. The catalysts achieve an NH3 production rate of 29.1 μg h−1 mgcat−1 and excellent Faradic efficiency of 11.5%, surpassing other Nb-based catalysts. The selectivity of NRR is assigned to the unique structure of the catalysts, including (1) the layered graphitic structure for fast electron transfer and active site distribution, (2) the reactive VO for N2 adsorption and activation, and (3) the expanded interlayer space for mass transfer.

Nitrogen Fixation at the Edges of Boron Nitride Nanomaterials: Synergy of Doping.

Synthesis of ammonia at ambient conditions is very demanding yet challenging to achieve due to the production of ammonia fuel, which is considered to be a future fuel for sustainable energy. In this context, computational studies on the catalytic activity of the edge sites of boron nitride nanomaterials for possible nitrogen reduction into ammonia have been investigated. Geometrical and electronic properties of zigzag and armchair B-open edges of BN sheet (BOE) models have been unraveled to substantiate their catalytic nature. Results reveal that BOE sites exhibit very high potential determining steps (PDS) of 2.0 eV. Doping of carbon (C) at the nitrogen center, which is vicinal to the BOE site reduces the PDS of the N2 reduction reaction (NRR) (to 1.18–1.33 eV) due to the regulation of charge distribution around the active BOE site. Further, the NRR at the C doped at various edge sites of a boron nitride sheet (BNS) has also been studied in detail. Among the 12 new C-doped defective BNS models, 9 model catalysts are useful for nitrogen activation through either chemisorption or physisorption. Among these, ZC N , AC N , and ZC BV models are efficient in catalyzing NRR with lower PDS of 0.86, 0.88, and 0.86 eV, respectively. The effect of carbon doping in tuning the potential requirements of NRR has been analyzed by comparing the relative stability of intermediates on the catalyst with and without carbon doping. Results reveal that C-doping destabilizes the intermediates compared to non-doped systems, thereby reducing the possibility of catalyst poisoning. However, their interactions with catalysts are good enough so that the NRR activity of the catalyst does not decrease due to C-doping.

Unveiling the Synergy of O‐Vacancy and Heterostructure over MoO3‐x/MXene for N2 Electroreduction to NH3

AbstractThe electrochemical N2 reduction reaction (NRR) offers a promising approach for sustainable NH3 production, and modulating the structural/electronic configurations of the catalyst materials with optimized electrocatalytic properties is pivotal for achieving high‐efficiency NRR electrocatalysis. Herein, vacancy and heterostructure engineering are rationally integrated to explore O‐vacancy‐rich MoO3‐x anchored on Ti3C2Tx‐MXene (MoO3‐x/MXene) as a highly active and selective NRR electrocatalyst, achieving an exceptional NRR activity with an NH3 yield of 95.8 µg h−1 mg−1 (−0.4 V) and a Faradaic efficiency of 22.3% (−0.3 V). A combination of in situ spectroscopy, molecular dynamics simulations and density functional theory computations is employed to unveil the synergistic effect of O‐vacancies and heterostructures for the NRR, which demonstrates that O‐vacancies on MoO3‐x serve as the active sites for N2 chemisorption and activation, while the MXene substrate can further regulate the O‐vacancy sites to break the scaling relation to effectively stabilize *N2/*N2H while destabilizing *NH2/*NH3, resulting in more optimized binding affinity of NRR intermediates toward reduced energy barriers and an enhanced NRR activity for MoO3‐x/MXene.