A review on the synthesis of transition metal nitride nanostructures and their energy related applications

Transition metal nitrides(TMN)have recently grabbed immensely appealing as ideal active materials in energy storage and catalysis fields on account of their remarkable electrical conductivity,excellent chemical stability,wide band gap and tunable morphology.Both pure TMN and TMN-based materials have been extensively studied concerned with their preparation approaches,nanostructures,and favored performance in various applications.However,the processes towards synthesis of TMN are numerous and complex.Choosing appropriate method to obtain target TMN with desired structure is crucial,which further affects its practical application performance.Herein,this review offers a timely and comprehensive summary of the synthetic ways to TMN and their application in energy related domains.The synthesis section is categorized into in-situ and ex-situ based on where the N element in TMN origins from.Then,overviews on the energy related applications including energy storage,electrocatalysis and photocatalysis are discussed.In the end,the problems to be solved and the development trend of the synthesis and application of transition metal nitrides are prospected.

Preparation and properties of transition metal nitrides caged in N-doped hollow porous carbon sphere for oxygen reduction reaction

A series of transition metal nitrides(MxNy,M=Fe,Co,Ni)nanoparticle(NP)composites caged in N-doped hollow porous carbon sphere(NHPCS)were prepared by impregnation and heat treatment methods.These composites combine the high catalytic activity of nitrides and the high-efficiency mass transfer characteristics of NHPCS.The oxygen reduction reaction results indicate that Fe2N/NHPCS has the synergistic catalytic performance of higher onset potential(0.96 V),higher electron transfer number(~4)and higher limited current density(1.4 times as high as that of commercial Pt/C).In addition,this material is implemented as the air catalyst for zinc−air battery that exhibits considerable specific capacity(795.1 mA·h/g)comparable to that of Pt/C,higher durability and maximum power density(173.1 mW/cm2).

Regulating non-precious transition metal nitrides bifunctional electrocatalysts through surface/interface nanoengineering for air-cathodes of Zn-air batteries

Zn-air batteries(ZABs),especially the secondary batteries,have engrossed a great interest because of its high specific energy,economical and high safety.However,due to the insufficient activity and stability of bifunctional electrocatalysts for air-cathode oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)processes,the practical application of rechargeable ZABs is seriously hindered.In the effort of developing high active,stable and cost-effective electrocatalysts,transition metal nitrides(TMNs)have been regarded as the candidates due to their high conductivity,strong corrosion-resistance,and bifunctional catalytic performance.In this paper,the research progress in TMNs-based material as ORR and OER electrocatalysts for ZABs is discussed with respect to their synthesis,chemical/physical characterization,and performance validation/optimization.The surface/interface nanoengineering strategies such as defect engineering,support binding,heteroatom introduction,crystal plane orientation,interface construction and small size effect,the physical and chemical properties of TMNs-based electrocatalysts are emphasized with respect to their structures/morphologies,composition,electrical conductivity,specific surface area,chemical stability and corrosion resistance.The challenges of TMNs-based materials as bifunctional air-cathode electrocatalysts in practical application are evaluated,and numerous research guidelines to solve these problems are put forward for facilitating further research and development.

The highly selective catalytic hydrogenation of CO_(2)to CO over transition metal nitrides

Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600℃,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400℃,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway.

Origin of superior pseudocapacitive mechanism of transition metal nitrides

Large-scale deployment of Internet of Things (IoT),a revolutionary innovation for a better world,is hampered by the limitation of energy self-sufficiency.Constructing transition metal nitride (TMN)-based micro-supercapacitors is a possible solution by taking advantage of the high conductivity,large specific capacitance,and large tap density of the materials.However,the pseudocapacitive storage mechanism of TMNs is still unclear consequently impeding the design of microdevices.Herein,the functions and mechanism of TMNs with different metal oxynitride (TMNO_(x)) concentrations in pseudocapacitive electrodes are investigated systematically by in situ Raman scattering,ex situ X-ray photoelectron spectroscopy,as well as ion isolation and substitution cyclic voltammetry.It is found that the specific capacitances of TMNs depend on the TMNO_(x) concentrations and the N–M–O site is responsible for the large pseudocapacitance via the Faradic reaction between TMNO_(x) and OH^(-).Our study elucidates the mechanism pertaining to pseudocapacitive charge storage of TMNs and provides insights into the design and optimization of TMNO_(x) as well as other electrode materials for pseudocapacitors.

Electric Field Induced Permanent Superconductivity in Layered Metal Nitride Chlorides HfNCl and ZrNCl

Devices of electric double-layer transistors （EDLTs） with ionic liquid have been employed as an effective way to dope carriers over a wide range. However, the induced electronic states can hardly survive in the materials after releasing the gate voltage VG at temperatures higher than the melting point of the selected ionic liquid. Here we show that a permanent superconductivity with transition temperature Tc of 24 and 15K is realized hi single crystals and polycrystalline samples of HfNCI and ZrNCI upon applying proper VG＇s at different temperatures. Reversible change between insulating and superconducting states can be obtained by applying positive and negative VG at low temperature such as 220K, whereas VG ＇s applied at 250K induce the irreversible superconducting transition. The upper critical field He2 of the superconducting states obtained at different gating temperatures shows similar temperature dependence. We propose a reasonable scenario that partial vacancy of Cl ions could be caused by applying proper VG＇s at slightly higher processing temperatures, which consequently results in a permanent electron doping in the system. Such a technique shows great potential to systematically tune the bulk electronic state in the similar two-dimensional systems.

General synthesis of transition metal nitride arrays by ultrafast flash Joule heating within 500 ms

Transition metal nitrides(TMNs)are considered as viable alternatives to noble metal catalysts owing to their versatile electronic structure and favorable catalytic performance.However,the conventional synthetic processes for TMNs suffer from high energy consumption and low production yield.In this study,a range of TMNs and their hetero-composite arrays were successfully synthesized via an ultrafast flash Joule heating technology within 0.5 s.As a proof concept,the nitrides and hetero-composites were applied for the electrocatalytic hydrazine oxidation reaction(HzOR),in which the Co_(4)N/Mo_(16)N_(7)arrays shows the best performance with a geometric current density of 100 mA cm^(-2)at 23 mV(vs.reversible hydrogen electrode(RHE)).This work paves a new way for the ultrafast synthesis of TMNs which could meet the ever-increased energy crisis.

Oxygen-modulated metal nitride clusters with moderate binding ability to insoluble Li_(2)S_(x) for reversible polysulfide electrocatalysis

Multiphase sulfur redox reactions with advanced homogeneous and heterogeneous electrochemical processes in lithium–sulfur(Li–S)batteries possess sluggish kinetics.The slow kinetics leads to significant capacity decay during charge/discharge processes.Therefore,electrocatalysts with adequate sulfurredox properties are required to accelerate reversible polysulfide conversion in cathodes.In this study,we have fabricated an oxygen-modulated metal nitride cluster(C-MoN_(x)-O)that has a moderate binding ability to the insoluble Li_(2)S_(x)for reversible polysulfide electrocatalysis.A Li–S battery equipped with CMoN_(x)-O electrocatalyst displayed a high discharge capacity of 875 mAh g^(-1)at 0.5 C.The capacity decay rate of each cycle was only 0.10%after 280 cycles,which is much lower than the control groups(C-MoO_(x):0.16%;C-MoN_(x):0.21%).Kinetic studies and theoretical calculations suggest that C-MoN_(x)-O electrocatalyst presents a moderate binding ability to the insoluble Li_(2)S_(2)and Li_(2)S when compared to the C-MoO_(x)and C-MoN_(x)surfaces.Thus,the C-MoN_(x)-O can effectively immobilize and reversibly catalyze the solid–solid conversion of Li_(2)S_(2)–Li_(2)S during charge–discharge cycling,thus promoting reaction kinetics and eliminating the shuttle effect.This study to design oxygen-doped metal nitrides provides innovative structures and reversible solid–solid conversions to overcome the sluggish redox chemistry of polysulfides.

Efficient Visible Light Hydrogen Evolution Catalyst Composed of Non-noble Metal Nitride (Ni_(3)N) Cocatalyst and Zn_(0.5)Cd_(0.5)S Solid Solution

In recent years,many effective photocatalysts have been developed to solve the problem of environmental pollution and clean energy shortage.In this paper,non-noble metal cocatalyst Ni_(3)N nanoparticles supported Zn_(0.5)Cd_(0.5)S(ZCS)nanorods(Ni_(3)N/ZCS)composites were successfully synthesized by ultrasonic method.The hydrogen production efficiencies of the photocatalysts were tested under visible light,which was found that when the loading of Ni_(3)N was 2%of the mass of ZCS,and the Ni_(3)N/ZCS composite had the best hydrogen evolution performance,which could reach 70.3 mmol·h^(-1)·g^(-1).In addition,the quantum efficiency under 420 nm monochromatic light irradiation was 27.2%.Through different characterization analyses,such as X-ray diffraction(XRD),scanning electron microscopy(SEM),and UV-Vis diffuse reflectance spectra(DRS),a possible photocatalytic mechanism was proposed,providing some reference values for non-precious metals as cocatalysts.

Hollow Ni Mo-based nitride heterojunction with super-hydrophilic/aerophobic surface for efficient urea-assisted hydrogen production

Hydrogen evolution reaction(HER)and urea oxidation reaction(UOR)are key reactions of the watercycling associated catalytic process/device.The design of catalysts with a super-hydrophilic/aerophobic structure and optimized electron distribution holds great promise.Here,we have designed a threedimensional(3D)hollow Ni/NiMoN hierarchical structure with arrayed-sheet surface based on a onepot hydrothermal route for efficient urea-assisted HER based on a simple hydrothermal process.The Ni/NiMoN catalyst exhibits super-hydrophilic/aerophobic properties with a small droplet contact angle of 6.07°and an underwater bubble contact angle of 155.7°,thus facilitating an escape of bubbles from the electrodes.Density functional theory calculations and X-ray photoelectron spectroscopy results indicate the optimized electronic structure at the interface of Ni and NiMoN,which can promote the adsorption/desorption of reactants and intermediates.The virtues combining with a large specific surface area endow Ni/NiMoN with efficient catalytic activity of low potentials of 25 mV for HER and 1.33 V for UOR at10 mA cm^(-2).The coupled HER and UOR system demonstrates a low cell voltage of 1.42 V at 10 mA cm^(-2),which is approximately 209 mV lower than water electrolysis.

Development of Transition Metal Nitrides as Oxygen and Hydrogen Electrocatalysts

With the increasing demand for energy, various emerging energy storage/conversion technologies have gradually penetrated human life, providing numerous conveniences. The practical application efficiency is often affected by the slow kinetics of hydrogen or oxygen electrocatalytic reactions(hydrogen evolution and oxidation reactions, oxygen evolution and reduction reactions) among the emerging devices. Therefore, the researchers devote to finding cost-effective electrocatalysts. Non-noble metal catalysts have low cost and good catalytic activity, but poor stability, agglomeration, dissolution, and other problems will occur after a long cycle, such as transition metal oxides and carbides. Transition metal nitrides(TMNs) stand out among all kinds of non-noble metal catalysts because of the intrinsic platinum-like electrocatalytic activities, relatively high conductivity, and wide range of tunability. In this review, the applications of TMNs in electrocatalytic fields are summarized based on the number of metals contained in TMNs. The practical application potentials of TMNs in fuel cell, water splitting, zinc-air battery and other electrochemical energy storage/conversion devices are also listed. Finally, the design strategies and viewpoints of TMNs-based electrocatalyst are summarized. The potential challenges of TMNs-based electrocatalyst in the development of electrocatalytic energy devices in the future are prospected.

Recent advances in pseudocapacitor electrode materials: Transition metal oxides and nitrides

Faraday pseudocapacitors take both advantages of secondary battery with high energy density and supercapacitors with high power density,and electrode material is the key to determine the performance of Faraday pseudocapacitors.Transition metal oxides and nitrides,as the two main kinds of pseudocapacitor electrode materials,can enhance energy density while maintaining high power capability.Recent advances in designing nanostructured architectures and preparing composites with high specific surface areas based on transition metal oxides and nitrides,including ruthenium oxides,nickel oxides,manganese oxides,vanadium oxides,cobalt oxides,iridium oxides,titanium nitrides,vanadium nitrides,molybdenum nitrides and niobium nitrides,are addressed,which would provide important significances for deep researches on pseudocapacitor electrode materials.

LDHs derived nanoparticle-stacked metal nitride as interlayer for long-life lithium sulfur batteries

Shuttle effect is one of the most serious disadvantages in lithium-sulfur battery which results in poor cycle performance and hinders the commercialization of Li-S battery.To reduce the dissolution of polysulfides into the electrolyte and prolong the cycling stability,nanoparticle-stacked metal nitride derived from layered double hydroxides(LDHs)as an interlayer was inserted between sulfur cathode and separator to confine polysulfides by physical and chemical interactions.Meanwhile,the surface of metal nitride will form an oxide passivation layer.The passivation layer possesses hydrophilic metal-O group and provides a polar surface for strong binding with polysulfide.What’s more,the nanoparticlesstacked structure could immerge and retain electrolyte well,which could enhance the ability of promoting the electron exchange rate.The sulfur electrode with nanoparticle-stacked metal nitride interlayer has an excellent cycle performance owing to the interactions between metal nitride and polysulfides.The battery delivered an initial capacity of 764.6 m Ahg^(-1) and still possesses a capacity of 477.5 mAhg^(-1) with the retention of 62.4% after 800 cycles.

Zirconium nitride as a highly efficient nitrogen source to synthesize the metal nitride clusterfullerenes

Metal nitride clusterfullerenes(NCFs)have significant applications in molecular electronics,biomedical imaging,and nonlinear optical devices due to their unique structures.However,their wide applications are limited by the production quantity.In this work,the yields of metal nitride clusterfullerenes M3N@C80(M=Y,Sc,Gd)were greatly enhanced by utilizing zirconium nitride(Zr N)as an efficient nitrogen source for the arc-discharge method.Compared with the traditional synthetic route using N2gas as nitrogen source,the Zr N inside graphite tube can be vaporized simultaneously with metal and graphite,and then afford the high concentration of nitrogen atoms in the arc region,which will promote the formation of metal nitride clusterfullerenes finally.The Zr N can promote the yields of Y3N@C80,Sc3N@C80and Gd3N@C80,revealing the universal applicability of Zr N as a highly efficient nitrogen source.Specifically,the yield of Sc3N@C80was greatly improved when adding Zr N,and it shows over double yield compared to traditional synthetic route using N2gas.In addition,Zr N can also enhance the yields of paramagnetic azametallofullerene M2@C79N due to the high concentration of nitrogen atoms in the arc region.This new method enhances the production quantity of metal nitride clusterfullerenes and azametallofullerenes,and it will greatly promote the research and application of these molecular carbon materials.

Calculation of Bulk Moduli of Carbon Nitride/metal Nitride Composites

ased on Marvin L. Cohen′s empirical approach, a simple model of calculation of bulk moduli of carbon nitride/metal nitride composites is shown. The calculated bulk modulus of the crystalline carbon nitride/TiN composite coating is comparable with that of cBN and diamond. This model predicts that the modulus of the composite is between the moduli of the two components.

Metal/antiperovskite metal nitride composites Ag/AgNNi_(3)as novel efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Searching for effective hydrogen evolution reaction(HER)electrocatalysts is crucial for water splitting.Transition metal nitrides(TMNs)are very attractive potential candidates since of high electrical conductivity,robust stability,element rich and high activity.Antiperovskite metal nitrides provide chemical flexibility since two different types of transition metal elements are contained,allowing partial substitution both for A-and M-sites.Herein,we report a novel antiperovskite metal nitride Ag_(x)Ni_(1-x)NNi_(3)(0≤x≤0.80)thin film used as highly effective HER electrocatalysts.Pure phase antiperovskite nitride can be successfully obtained for Ag_(x)Ni_(1-x)NNi_(3)with x less than 0.80.The Ag_(0.76)Ni_(0.24)NNi_(3) towards HER shows an overpotential of 122 mV at 10 mA cm^(-2)in alkaline media.Furthermore,considering the role of Ag for adsorbing hydroxyl groups,chemical engineering has been carried out for designing metal/antiperovskite nitride Ag/Ag_(x)Ni_(1-x)NNi_(3)composite electrocatalysts.The 0.18 Ag/Ag_(0.80)Ni_(0.20)NNi_(3)electrocatalyst shows a mere 13 and 81 mV of overpotential to reach 1 and 10 mA cm^(-2),respectively,showing high durability in alkaline media.These results will provide a novel type of HER catalysts based on antiperovskite metal nitrides and a strategic design for metal/antiperovskite metal nitride composite electrocatalysts for HER in alkaline media.

Sabatier principle guiding the design of cathode catalysts for Li-CO_(2) batteries

The Sabatier principle has been widely used for designing electrocatalysts for energy conversion applications,but it is rarely mentioned in the research of cathode catalyst of Li-CO_(2) batteries.In our work,the"volcanic"relationship between the catalytic activity and the adsorption energy of the catalyst to the intermediates is first demonstrated based on the first-principles calculation,which meets the Sabatier principle and can be used to design the cathode catalysts.The increases in the number of nitrogenvacancy in WN shift the d-band center and increase the interaction with the reactants.The catalytic activity increases first and then decreases with the increase of adsorption energy,which was proved in the experiment.The optimal catalyst for moderate adsorption of intermediate makes the thin LiaCO_(3) distribute evenly.It exhibits a median voltage difference of 0.68 V and an energy efficiency of 84.33%at20μA cm^(-2)with a limited capacity of 200μA h cm^(-2).

Paired formate and H_(2) productions via efficient bifunctional Ni-Mo nitride nanowire electrocatalysts

Electrocatalytic water splitting provides a potentially sustainable approach for hydrogen production,but is typically restrained by kinetically slow anodic oxygen evolution reaction(OER)which is of lesser value.Here,free-standing,hetero-structured Ni_(3)N-Ni_(0.2)Mo_(0.8)N nanowire arrays are prepared on carbon cloth(CC)electrodes for hydrogen evolution reaction(HER)and glycerol oxidation reaction(GOR)to formate with a remarkably high Faradaic efficiency of 96%.A two-electrode electrolyzer for GOR-assisted hydrogen production operates with a current density of 10 mA cm^(-2)at an applied cell voltage of 1.40 V,220 mV lower than for alkaline water splitting.In-situ Raman measurements identify Ni(Ⅲ)as the active form of the catalyst for GOR rather than Ni(IV)and in-situ Fourier transform infrared(FTIR)spectroscopy measurements reveal pathways for GOR to formate.From density functional theory(DFT)calculations,the Ni_(3)N-Ni_(0.2)Mo_(0.8)N heterostructure is beneficial for optimizing adsorption energies of reagents and intermediates and for promoting HER and GOR activities by charge redistribution across the heterointerface.The same electrode also catalyzes conversion of ethylene glycol from polyethylene terephthalate(PET)plastic hydrolysate into formate.The combined results show that electrolytic H_(2) and formate production from alkaline glycerol and ethylene glycol solutions provide a promising strategy as a cost-effective energy supply.

^(15)N/^(14)N Isotopic Exchange in the Dissociative Adsorption of N_(2) on Tantalum Nitride Cluster Anions Ta_(3)N_(3)

Adsorption and activation of dinitrogen(N_(2)) is an indispensable process in nitrogen fixation.Metal nitride species continue to attract attention as a promsing catalyst for ammonia synthesis.However,the detailed mechanisms at a molecular level between reactive nitride species and N_(2) remain unclear at elevated temperature,which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase system.Herein,the ^(15)N/^(14)N isotopic exchange in the reaction between tantalum nitride cluster anions Ta_(3)^(14)N_(3)^(-) and ^(15)N_(2) leading to the regeneration of ^(14)N_(2)/^(14)N^(15)N was observed at elevated temperature(393-593 K)using mass spectrometry.With the aid of theoretical calculations,the exchange mechanism and the effect of temperature to promote the dissociation of N_(2) on Ta_(3)N_(3)^(-) were elucidated.A comparison experiment for Ta_(3)^(14)N_(4)^(-)/^(15)N_(2) couple indicated that only desorption of ^(15)N_(2) from Ta_(3)^(14)N_(4)^(15)N_(2)^(-) took place at elevated temperature.The different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride species.This study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.

Remarkable synergistic effect in cobalt-iron nitride/alloy nanosheets for robust electrochemical water splitting

Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable energy consumption.Herein,a simple three-step strategy is reported to construct cobalt-iron nitride/alloy nanosheets on nickel foam(CoFe-NA/NF)as a bifunctional catalyst for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The electrocatalyst with optimized composition(CoFe-NA2/NF)can achieve ultralow overpotentials of 73 mV and 250 mV for HER and OER,respectively,at a current density of 10 mA cm^(-2) in 1 M KOH.Notably,the electrolyzer based on this electrocatalyst is able to boost the overall water splitting with a cell voltage of 1.564 V to deliver 10 mA cm^(-2) for at least 50 h without obvious performance decay.Furthermore,our experiment and theoretical calculation demonstrate that the combination of cobalt-iron nitride and alloy can have low hydrogen adsorption energy and facilitate water dissociation during HER.In addition,the surface reconstruction introduces metal oxyhydroxides to optimize the OER process.Our work may pave a new pathway to design bifunctional catalysts for overall water splitting.