Chemisorption Of N2 Research Articles

Modulating Nitrogen Adsorption Mode and Microenvironment of Active Sites for Boosting Electrochemical Nitrogen Reduction.

Electrochemical reduction of N2(NRR) offers a sustainable approach for ammonia (NH3) synthesis, serving as a complementary to the traditional emission- and energy-intensive Haber-Bosch process. However, it faces challenges in N2 activation and competing with pronounced hydrogen evolution reaction (HER). Herein an efficient electrocatalyst comprised of ultrafine Ru nanoclusters (NCs) confined by a hydrophobic molecular layer is developed on the surface of 2D Ti3C2Tx for NRR. These experimental and theoretical calculation results demonstrate that 1) ultrafine Ru NCs dispersed on the Ti3C2Tx surface form paired active sites for N2 chemisorption in a unique tilted configuration with low-energy activation 2) the hydrophobic molecular layer modulates the local microenvironment surrounding catalytically active sites, enabling efficient N2 accumulation while repelling H2O diffusion to the active sites on the Ti3C2Tx surface, thereby leading to an increased N2 concentration and suppressed HER. As a result, an exceptionally high NH3 yield rate of 33.5µg h-1mg-1cat and Faradaic efficiency of 65.3% are obtained at -0.25V versus reversible hydrogen electrode (RHE) in 0.1m Na2SO4, outperforming those previously reported Ti3C2Tx-derived electrocatalysts. This work provides a valuable strategy for the rational design of advanced electrocatalysts by manipulating active sites and local microenvironments for efficient electrocatalysis.

Triggering Heteroatom Ensemble Effect over RuFe Alloy to Promote Nitrogen Chemisorption for Efficient Ammonia Electrosynthesis at Ambient Conditions.

Ammonia (NH3) electrosynthesis from nitrogen (N2) provides a promising strategy for carbon neutrality, circumventing the energy-intensive and carbon-emitting Haber-Bosch process. However, the current system still presents unsatisfactory performance, and the bottleneck lies in the rational synthesis of catalytic centers with efficient N2 chemisorption ability. Herein, a heteroatom ensemble effect is deliberately triggered over RuFe alloy with spatial proximity of metal sites to promote electrocatalytic nitrogen reduction. The heteronuclear RuFe ensemble with increased surface polarization and modulated electronic structure offers the feasibility to optimize the adsorption configuration of electroactive substances and facilitate chemical bond scission. The promotion of N2 chemisorption and the following hydrogenation are demonstrated by the in situ Fourier transform infrared spectroscopy characterizations. The catalyst thus permits significantly enhanced conversion of N2 to NH3 in a 0.1 M HCl environment, with a maximum ammonia yield rate of 75.45 μg h-1 mg-1 and a high Faradaic efficiency of 35.49%.

Defect modulation of MIL-68(Fe) MOFs by Cu doping for boosting photocatalytic N2 fixation

Photocatalytic N2 fixation is a green process for ammonia synthesis by converting N2 and H2O to NH3 and O2 directly using solar energy. Its efficiency is largely limited by the chemisorption and activation of N2. This work adopts defect engineering strategy to develop a series of MIL-68(Fe) MOFs with varying concentrations of defects by doping Cu2+ on the metal nodes of MOFs. Upon Cu2+ doping, a larger number of oxygen vacancy defects are created due to the induced crystal distortion to form coordinatively unsaturated Fe2+ sites, which can serve as the active sites for promoting the chemisorption and activation of N2. The photogenerated holes oxidize H2O to O2 and H+, and the photogenerated electrons combine with formed H+ to reduce the activated N2 to NH3. It was found that the sample with 10 mol% Cu2+ doping shows the highest NH3 production rate (21.0 μmol·g−1·h−1), which is 8.4 times higher than that (2.50 μmol·g−1·h−1) of the pristine MIL-68(Fe). The excellent performance is ascribed to the adequate Fe2+ active sites to chemisorb and activate N2 and the optimal mobility of photogenerated charges. Finally, a mechanism is proposed to illustrate how the number of defects affects the photocatalytic N2 fixation performance at the molecular level.

Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply.

Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.

In-MOF derived In2S3-X@ZnS heterojunction with rich sulfur vacancies for enhanced performance in photocatalytic nitrogen fixation

Photocatalytic nitrogen fixation has the characteristics of green, energy-saving and environment-friendly. Herein, the hollow microtube-flower In2S3-X@ZnS with rich sulfur vacancies was synthesized by the one-step solvothermal method of sulfurization from the precursor MIL-68(In). In-MOF derived sulfur-vacancy modulation and the construction of the In2S3-X@ZnS heterojunction had been proved to be the desirable strategies to dramatically enhance the ammonia production rate. One the one hand, the characterizations of HRTEM, ESR and the transient photocurrent responses (TPR) in N2, Air and Ar saturated solution directly and indirectly proved the existence of rich sulfur-vacancy, which could be the active sites for the chemisorption and activation of N2. On the other hand, the results of EIS, PL and band analysis demonstrated that the established Type-п heterojunction promoted the photogenerated carriers to separate and clarified the enhanced photocatalytic mechanism, the corresponding nitrogen fixation performance had been greatly improved with a high yield rate of 58.988 µmol∙gcat−1∙h−1, which was evidently much higher than that of pristine In2S3-X and pure ZnS. This work provided a new insight for developing functional photocatalysts with the synergy effect of sulfur-vacancy and heterojunction for highly efficient nitrogen fixation.

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.

Synergistic Spatial Confining Effect and O Vacancy in WO3 Hollow Sphere for Enhanced N2 Reduction.

Visible-light-driven N2 reduction into NH3 in pure H2O provides an energy-saving alternative to the Haber-Bosch process for ammonia synthesizing. However, the thermodynamic stability of N≡N and low water solubility of N2 remain the key bottlenecks. Here, we propose a solution by developing a WO3-x hollow sphere with oxygen vacancies. Experimental analysis reveals that the hollow sphere structure greatly promotes the enrichment of N2 molecules in the inner cavity and facilitates the chemisorption of N2 onto WO3-x-HS. The outer layer's thin shell facilitates the photogenerated charge transfer and the full exposure of O vacancies as active sites. O vacancies exposed on the surface accelerate the activation of N≡N triple bonds. As such, the optimized catalyst shows a NH3 generation rate of 140.08 μmol g-1 h-1, which is 7.94 times higher than the counterpart WO3-bulk.

Unraveling Synergistic Effect of Defects and Piezoelectric Field in Breakthrough Piezo-Photocatalytic N2 Reduction.

Piezo-photocatalysis is a frontier technology for converting mechanical and solar energies into crucial chemical substances and has emerged as a promising and sustainable strategy for N2 fixation. Here, for the first time, defects and piezoelectric field are synergized to achieve unprecedented piezo-photocatalytic nitrogen reduction reaction (NRR) activity and their collaborative catalytic mechanism is unraveled over BaTiO3 with tunable oxygen vacancies (OVs). The introduced OVs change the local dipole state to strengthen the piezoelectric polarization of BaTiO3 , resulting in a more efficient separation of photogenerated carrier. Ti3+ sites adjacent to OVs promote N2 chemisorption and activation through d-π back-donation with the help of the unpaired d-orbital electron. Furthermore, a piezoelectric polarization field could modulate the electronic structure of Ti3+ to facilitate the activation and dissociation of N2 , thereby substantially reducing the reaction barrier of the rate-limiting step. Benefitting from the synergistic reinforcement mechanism and optimized surface dynamics processes, an exceptional piezo-photocatalytic NH3 evolution rate of 106.7µmolg-1 h-1 is delivered by BaTiO3 with moderate OVs, far surpassing that of previously reported piezocatalysts/piezo-photocatalysts. New perspectives are provided here for the rational design of an efficient piezo-photocatalytic system for the NRR.

Boosting Photocatalytic Nitrogen Fixation via Nanoarchitectonics Using Oxygen Vacancy Regulation in W-Doped Bi2MoO6 Nanosheets.

Ammonia and nitrates are key raw materials for various chemical and pharmaceutical industries. The conventional methods like Haber-Bosch and Ostwald methods used in the synthesis of ammonia and nitrates, respectively, result in harmful emission of gases. In recent years, the photocatalytic fixation of N2 into NH3 and nitrates has become a hot topic since it is a green and cost-effective approach. However, the simultaneous production of ammonia and nitrates has not been studied much. In this regard, we have synthesized W-doped Bi2MoO6 nanosheets in various molar ratios and demonstrated their potential as efficient photocatalysts for the simultaneous production of NH3 and NO3- ions under visible light irradiation. It was found that one of the catalysts (BMWO0.4) having an optimal molar ratio of doped tungsten showed the best photocatalytic NH3 production (56 μmol h-1) without using any sacrificial agents along with the simultaneous production of NO3- ions at a rate of 7 μmol h-1. The enhanced photocatalytic activity of the synthesized photocatalysts could be ascribed to oxygen vacancy defects caused by Mo substitution by a more electronegative W atom. Furthermore, density functional theory calculations verified the alteration in the band gap after doping of W atoms and also showed a strong chemisorption of N2 over the photocatalyst surface leading to its activation and thereby enhancing the photocatalytic activity. Thus, the present work provides insights into the effect of structural distortions on tailoring the efficiency of materials used in photocatalytic N2 fixation.

Frustrated Lewis pairs-engineered boron-doped 3D carbon nitride for improved electrocatalytic nitrogen reduction

It is of great importance to explore metal-free electrocatalysts with high electrocatalytic nitrogen reduction reaction (NRR) activity for ammonia (NH3) production. This work for the first time reports a three-dimensional (3D) boron (B) doped carbon nitride with frustrated Lewis pairs and deficiencies for efficient NRR via a facile copolymerization of sodium borohydride and urea precursors. The texture and the amount of B dopants in the resultant 3D carbon nitride can be finely tuned by varying the dosage of sodium borohydride. With the optimal B-doping content, the formed honeycomb-like 3D catalyst has a high NH3 yield rate of 17.8 μg h−1 mg−1 and Faradaic efficiency of 9.85% in 0.1 M Na2SO4 and 0.05 M H2SO4 electrolyte at −1.4 V vs RHE, which is considerably better than the undoped 3D carbon nitride. Comprehensive characterizations reveal that for the B-doped 3D carbon nitride, the unique 3D structure makes more introduced cyano groups and exposed nitrogen defects, favoring the contact between the electrolyte and the active sites. The abundant unsaturated B and N atoms function as frustrated Lewis pairs to strengthen N2 chemisorption and activation, lowing the barrier of NRR and meanwhile suppressing hydrogen evolution reaction. Moreover, in-situ UV–vis spectroscopy elucidates that the optimal potential at −1.4 V vs RHE benefits free electrons to participate in the NRR reaction because it matches the conduction potential of B-UCN-15. This study provides a new avenue for the rational design of nonmetal-based catalysts for NRR.

Mo2P Monolayer as a Superior Electrocatalyst for Urea Synthesis from Nitrogen and Carbon Dioxide Fixation: A Computational Study

Urea synthesis through the simultaneous electrocatalytic reduction of N2 and CO2 molecules under ambient conditions holds great promises as a sustainable alternative to its industrial production, in which the development of stable, highly efficient, and highly selective catalysts to boost the chemisorption, activation, and coupling of inert N2 and CO2 molecules remains rather challenging. Herein, by means of density functional theory computations, we proposed a new class of two‐dimensional nanomaterials, namely, transition‐metal phosphide monolayers (TM2P, TM = Ti, Fe, Zr, Mo, and W), as the potential electrocatalysts for urea production. Our results showed that these TM2P materials exhibit outstanding stability and excellent metallic properties. Interestingly, the Mo2P monolayer was screened out as the best catalyst for urea synthesis due to its small kinetic energy barrier (0.35 eV) for C–N coupling, low limiting potential (−0.39 V), and significant suppressing effects on the competing side reactions. The outstanding catalytic activity of the Mo2P monolayer can be ascribed to its optimal adsorption strength with the key *NCON species due to its moderate positive charges on the Mo active sites. Our findings not only propose a novel catalyst with high‐efficiency and high‐selectivity for urea production but also further widen the potential applications of metal phosphides in electrocatalysis.

Disordered Au Nanoclusters for Efficient Ammonia Electrosynthesis.

The electrochemical nitrogen (N2 ) reduction reaction (N2 RR) under mild conditions is a promising and environmentally friendly alternative to the traditional Haber-Bosch process with high energy consumption and greenhouse emission for the synthesis of ammonia (NH3 ), but high-yielding production is rendered challenging by the strong nonpolar N≡N bond in N2 molecules, which hinders their dissociation or activation. In this study, disordered Au nanoclusters anchored on two-dimensional ultrathin Ti3 C2 Tx MXene nanosheets are explored as highly active and selective electrocatalysts for efficient N2 -to-NH3 conversion, exhibiting exceptional activity with an NH3 yield rate of 88.3±1.7 μg h-1 mgcat. -1 and a faradaic efficiency of 9.3±0.4 %. A combination of in situ near-ambient pressure X-ray photoelectron spectroscopy and operando X-ray absorption fine structure spectroscopy is employed to unveil the uniqueness of this catalyst for N2 RR. The disordered structure is found to serve as the active site for N2 chemisorption and activation during the N2 RR process.

Comparative study on CuO–La2O3/ZrO2 catalysts prepared by amino acid complexing‐combustion in CO2 hydrogenation

AbstractFor preparation of functional materials, the facile and efficient complexing‐combustion method has many advantages such as the easily operating, no washing and filtration process, a slight loss of the products obtained, material saving, and so on. Here, CuO–La2O3/ZrO2 catalysts were prepared by using various amino acids as complexing‐combustion agents for CO2 hydrogenation to methanol. Based on the results of characterization by N2 physical adsorption, SEM, XRD, XPS, and chemisorption, along with the experimental data, it was found that the structure and catalytic activity of as‐obtained catalysts depended on the group type and carbon chain length of amino acids. Among them, L‐glutamic acid had two carboxyl hydrophilic groups and a moderately long carbon chain, which was conducive to the formation of a larger specific surface area along with abundant pores and a smaller grain size of CuO. Moreover, the prepared catalyst showed a higher Cu dispersion and the abundant surface acidic/basic sites. As a result, the larger Cu+/Cu0 surface area contributed to the active adsorption of H2 and CO2 molecules, which greatly improved the hydrogenation of CO2, while the methanol production increased with the increase of surface basicity/acidity. For example, the selectivity to methanol of 87.9%, which corresponded to a methanol yield of 120 mg/(h gcatalyst), was obtained along with a stable online performance (life span more than 144 h) at 2.2 MPa, 220°C, H2/CO2 = 2, and GHSV = 3000 h−1.

Boosting charge-transfer in tuned Au nanoparticles on defect-rich TiO2 nanosheets for enhancing nitrogen electroreduction to ammonia production

The electrocatalytic nitrogen reduction reaction (eNRR) to ammonia (NH3) has been recognized as an effective, carbon–neutral, and great-potential strategy for ammonia production. However, the conversion efficiency and selectivity of eNRR still face significant challenges due to the slow transfer kinetics and lack of effective N2 adsorption and activation sites in this process. Herein, we designed and fabricated defect-rich TiO2 nanosheets furnished with oxygen vacancies (OVs) and Au nanoparticles (Au/TiO2-x) as the electrocatalyst for efficient N2-fixing. The experimental results demonstrate that OVs act as active sites, which enable efficient chemisorption and activation of N2 molecules. The Au nanoparticles loaded on the OVs-rich TiO2 nanosheets not only accelerate charge transfer but also change the local electronic structure, thus enhancing N2 adsorption and activation. In this work, the optimal Au/TiO2-x electrocatalyst displays a considerable NH3 yield activity of 12.5 μg h−1 mgcat.-1 and a faradaic efficiency (FE) of 10.2 % at −0.40 V vs reversible hydrogen electrode (RHE). More importantly, the Au/TiO2-x exhibits a stable N2-fixing activity in cycling and it persists even after 80 h of consecutive electrolysis. Density functional theory (DFT) calculations reveal that the OVs serve as the active sites in TiO2, while Au nanoparticles are crucial for improving N2 chemisorption and lowering the reaction energy barrier by facilitating the charge transfer for eNRR with a distal hydrogenation pathway. This research offers a rational catalytic site design for modulating charge transfer of active sites on metal-supported defective catalysts to boost N2 electroreduction to NH3.

Recent Advances in NH3 Synthesis with Chemical Looping Technology

Ammonia economy is expected to provide a long-term solution without carbon emission to relieve environmental burdens and tackle traditional fossil fuel depletion. NH3 synthesis with chemical loop technology is a promising NH3 production alternative with independence from fossil fuels, high product selectivity, and simplified operation under milder conditions. Looped nitrogen carriers provide a chemical looping ammonia synthesis (CLAS) process with thermodynamic and/or kinetic advantages via decoupling scaling relations and circumventing competitive chemisorption of N2 and H2/H2O. The approach has great flexibility in material and process design, and individual steps can thus be optimized separately. This review summarizes the recent progress related to the CLAS process. Four routines (i.e., H2-TM CLAS, H2-AH CLAS, H2O-2step CLAS, and H2O-3step CLAS) are analyzed and compared as well as the plant configurations using chemical looping technology to generate feedstocks for Haber–Bosch NH3 synthesis. The corresponding challenges are also presented, and potential solutions are discussed.

Microenvironment Regulation of the Ti3C2Tx MXene Surface for Enhanced Electrochemical Nitrogen Reduction.

The overwhelmingly competitive hydrogen evolution reaction (HER) is a bottleneck challenge in the electrocatalytic nitrogen reduction reaction (eNRR) process. Herein, we develop a general and effective strategy to suppress the HER via covalent surface functionalization to modulate the local microenvironment of the electrocatalyst. A hydrophobic molecular layer with tunable coverage density was coated on the surface of Ti3C2Tx MXene, and the one with appropriate coverage density significantly improved the eNRR efficiency with an excellent faradaic efficiency (FE) of 38.01% at -0.35 V and a high NH3 yield rate of 17.81 μg h-1mgcat-1 at -0.55 V (vs RHE) in a Na2SO4 solution, which were 3.5-fold in FE and 6.5-fold in NH3 yield rate higher than those of the pristine Ti3C2Tx. Experimental results combined with molecular dynamics (MD) simulations reveal that the hydrophobic molecular layer on the surface greatly limits the proton transfer and benefits higher exposure of active sites with enhanced N2 chemisorption ability, which cumulatively contribute to the boosted eNRR efficiency.

Transition metal modified 3DOM WO3 with activated N N bond triggering high-efficiency nitrogen photoreduction

Photocatalytic nitrogen fixation is a promising green strategy for ammonia synthesis, yet the high activation energy for nitrogen is the significant limitation to its practical application. Herein, a novel Fe-doped WO3 photocatalyst with three dimensional macroporous (3DOM) structure was designed and prepared. This special photocatalyst not only provides effective adsorption active sites to enhance the chemisorption and activation of N2, but also promotes the charge separation and transfer from catalyst to nitrogen. As a result, the optimized 5% Fe-3DOM WO3 sample achieves excellent ammonia production rate of 60 μmol g−1h−1, ∼30 times higher than that of pure 3DOM WO3. The in-situ DRIFTS results show the existence of several intermediates containing NH bonds during nitrogen reduction. Meanwhile, the density functional theory calculation results show that the presence of Fe promotes the adsorption and activation of nitrogen, and the reaction pathway is biased towards the alternate hydrogenation mechanism.

Doped 2D VX2 (X = S, Se, Te) monolayers as electrocatalysts for ammonia production: A DFT based study

Electrocatalytic nitrogen fixation under ambient conditions on vanadium dichalcogenides (VX2) with non-metal dopants has been explored herein. Understanding the interface chemistry, inherent electronic and acute synergistic nature of non-metal dopants on two unique phases of VX2 has been meticulously explored through a scrutiny of several non-metal atoms as catalytic centers. The efficacity of N2 chemisorption and NN bond activation has been implemented as crucial parameters to realize boron and carbon doped VX2 monolayers to be electrocatalytically active for nitrogen reduction reaction (NRR). Detailed investigation on the NRR mechanism brings out the pivotal role of thermodynamic favourability for product formation obtained from Gibbs free energy differences. The charge transfer on N and π-π* orbital hybridization and electron “donor–acceptor” mechanism between the non-metal and N2 has been found to modulate the electrocatalytic barrier for NRR on VX2 monolayers. This study proposes boron doped VS2 as an efficient chemically feasible, earth abundant sustainable electrocatalyst for NRR with an overpotential as low as 0.06 eV.

Effects of vibrational and rotational excitations on dissociative chemisorption dynamics of N2 on Fe(111)

The dissociative chemisorption of N2 is the rate-limiting step for ammonia synthesis in industry. Here, we investigated the role of initially vibrational excitation and rotational excitation of N2 for its reactivity on the Fe(111) surface, based on a recently developed six-dimensional potential energy surface. Six-dimensional quantum dynamics study was carried out to investigate the effect of vibrational excitation for incidence energy below 1.6 eV, due to significant quantum effects for this reaction. The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations. We found that raising the translational energy can enhance the dissociation probability to some extent, however, the vibrational excitation or rotational excitation can promote dissociation more efficiently than the same amount of translational energy. This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.

Modulating the Oxidation State of Titanium via Dual Anions Substitution for Efficient N2 Electroreduction.

The electrocatalytic nitrogen reduction reaction (NRR) is a promising approach for renewable ammonia synthesis but remains significantly challenging due to the low yield and poor selectivity. Herein, a facile N and S dual anions substitution strategy is developed to tune the Ti oxidation states of TiO2 nanohybrid catalyst (NS-TiO2 /C), in which anatase TiO2 nanoplates with dense Ti3+ active sites are uniformly dispersed on porous carbon derived from 2D Ti3 C2 Tx nanosheets. The catalyst NS-TiO2 /C exhibits a superior ambient NRR efficiency with an NH3 yield rate of 19.97µg h-1 mg-1cat and Faradaic efficiency of 25.49% and is coupled with a remarkable 50 h long-term stability at -0.25V versus RHE. Both experimental and theoretical results reveal that the N and S dual-substitution effectively regulate the Ti oxidation state and electronical properties of the NS-TiO2 /C via simultaneously forming interstitial and substitutional TiS and TiN bonds in the anatase TiO2 lattice, inducing oxygen vacancies and dense Ti3+ active species as well as better electronic conductivity, which substantially facilitates N2 chemisorption and activation, and reduces the energy barrier of the rate-determining step, thereby essentially boosting NRR efficiency. This work provides a valuable approach to the rational design of advanced materials by modulating oxidation states for efficient electrocatalysis.