Transition metal nitrides have been suggested to have both high hardness and good thermal stability with large potential application value, but so far stable superhard transition metal nitrides have not been synthesiz...Transition metal nitrides have been suggested to have both high hardness and good thermal stability with large potential application value, but so far stable superhard transition metal nitrides have not been synthesized. Here, with our newly developed machine-learning accelerated crystal structure searching method, we designed a superhard tungsten nitride, h-WN6, which can be synthesized at pressure around 65 GPa and quenchable to ambient pressure. This h-WN6 is constructed with single-bonded armchair-like N6 rings and presents ionic-like features, which can be formulated as W^2.4＋N^2.4-. It has a band gap of 1.6 eV at 0GPa and exhibits an abnormal gap broadening behavior under pressure. Excitingly, this h-WN6 is found to be the hardest among transition metal nitrides known so far （Vickers hardness around 57 GPa） and also has a very high melting temperature （around 1,900 K）. Additionally, the good gravimet- ric （3.1 kJ/g/and volumetric （28.0 kJ/cm3） energy densities make this nitrogen-rich compound a potential high-energy-density material, These predictions support the designing rules and may stimulate future experiments to synthesize superhard and high-energy-density material.展开更多
A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the amm...A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.展开更多
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 affec...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.展开更多
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 proces...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.展开更多
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 optim...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.展开更多
Metal nitrides are widely studied due to their outstanding physical properties, including high hardness,high thermal and chemical stability, low electrical resistivity etc. Generally, metal nitrides can be obtained fr...Metal nitrides are widely studied due to their outstanding physical properties, including high hardness,high thermal and chemical stability, low electrical resistivity etc. Generally, metal nitrides can be obtained from the direct reaction of metal and ammonia/nitrogen. However, some of the metal nitrides,such as Ta_3N_5, cannot be synthesized by direct nitridation of metals. To achieve Ta_3N_5, high-oxidationstate Ta precursors like Ta_2O_5, NaTaO_3, TaS_3, K_6Ta_(10.8)O_(30), Ta(N(CH_3)_2)_5 and TaCl_5 have to be employed,which is a time-consuming and laborious process with the possibility of introducing undesirable impurities. Here taking Ta_3N_5 as an example, a facile carbonate-assisted one-step nitridation method is proposed, which enables the direct synthesis of high-oxidation-state metal nitride films from metal precursors under ammonia flow. The mechanism of the nitridation process has been studied, which carbon dioxide released from carbonates decomposition reacts with metallic Ta and assists the one-step conversion of metallic Ta to Ta_3N_5. The as-prepared Ta_3N_5 film, after modified with NiFe layered double hydroxide, exhibits promising water splitting performance and stability. This method avoids the preoxidation process of metal precursors in high-oxidation-state metal nitride synthesis, and may facilitate the direct fabrication of other important metal nitrides besides Ta_3N_5.展开更多
Ni-based transition metal nitrides(TMNs)have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction(HER)due to their low cost,excellent chemical stability,high ...Ni-based transition metal nitrides(TMNs)have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction(HER)due to their low cost,excellent chemical stability,high electronic conductivity,and unique electronic structure.However,facile green synthesis and rational microstructure design of Ni-based TMNs electrocatalysts with high HER activity remain challenging.In this work,we report the fabrication of Ni/Ni_(3)N heterostructure nanoarrays on carbon paper via a one-step magnetron sputtering method under low temperature and N2 atmosphere.The Ni/Ni_(3)N hierarchical nanoarrays exhibit an excellent HER catalytic activity with a low overpotential of 37 mV at 10 mA·cm^(−2)and robust long-term durability over 100 h.Furthermore,the Ni/Ni_(3)N||NiFeOH(NiFeOH=NiFe bimetallic hydroxide)electrolyzer requires a small voltage of 1.54 V to obtain 10 mA·cm^(−2)for water electrolysis.Density functional theory(DFT)calculations reveal that the heterointerface between Ni and Ni_(3)N could directly induce electron redistribution to optimize the electronic structure,which accelerates the dissociation of water molecules and the subsequent hydrogen desorption,and thus boosting the HER kinetics.展开更多
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 pseudoc...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.展开更多
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...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).展开更多
High-pressure solid-state metathesis(HPSSM)reaction is an effective route to novel metal nitrides.A recent advance in HPSSM reactions is presented for a number of examples,including 3d transition metal nitrides(ε-Fe_...High-pressure solid-state metathesis(HPSSM)reaction is an effective route to novel metal nitrides.A recent advance in HPSSM reactions is presented for a number of examples,including 3d transition metal nitrides(ε-Fe_(3)N,ε-Fe_(3-x)Co_(x)N,CrN,and Co_(4)N_(x)),4d transition metal nitrides(MoNx),and 5d transition metal nitrides(Re_(3)N,WN_(x)).Thermodynamic investigations based on density functional theory(DFT)calculations on several typical HPSSM reactions between metal oxides and boron nitride indicate that the pressure could reduce the reaction enthalpy △H.High-pressure confining environment thermodynamically favors an ion-exchange process between metal atom and boron atom,and successfully results in the formation of well-crystalized metal nitrides with potential applications.展开更多
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,f...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.展开更多
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 bifunc...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.展开更多
基金financially supported by the Ministry of Science and Technology of the People’s Republic of China (2016YFA0300404 and 2015CB921202)the National Natural Science Foundation of China (51372112 and 11574133)+2 种基金the NSF of Jiangsu Province (BK20150012)the Fundamental Research Funds for the Central Universities,the Science Challenge Project (TZ2016001)Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase) under Grant No.U1501501
文摘Transition metal nitrides have been suggested to have both high hardness and good thermal stability with large potential application value, but so far stable superhard transition metal nitrides have not been synthesized. Here, with our newly developed machine-learning accelerated crystal structure searching method, we designed a superhard tungsten nitride, h-WN6, which can be synthesized at pressure around 65 GPa and quenchable to ambient pressure. This h-WN6 is constructed with single-bonded armchair-like N6 rings and presents ionic-like features, which can be formulated as W^2.4＋N^2.4-. It has a band gap of 1.6 eV at 0GPa and exhibits an abnormal gap broadening behavior under pressure. Excitingly, this h-WN6 is found to be the hardest among transition metal nitrides known so far （Vickers hardness around 57 GPa） and also has a very high melting temperature （around 1,900 K）. Additionally, the good gravimet- ric （3.1 kJ/g/and volumetric （28.0 kJ/cm3） energy densities make this nitrogen-rich compound a potential high-energy-density material, These predictions support the designing rules and may stimulate future experiments to synthesize superhard and high-energy-density material.
文摘A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.
基金supported by the Natural Science Foundation of Jiangsu Province (No. BK20191430)Six Talent Peaks Project in Jiangsu Province (No. XNY-009)+2 种基金High-tech Research Key Laboratory of Zhenjiang (No. SS2018002)Jiangsu Province Key Laboratory of Intelligent Building Energy Efficiency (No. BEE201904)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘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.
基金supported by the National Natural Science Foundation of China(22375001)the Natural Science Foundation of Anhui Province(2208085Y03,2208085QB30)+2 种基金the University Synergy Innovation Program of Anhui Province(GXXT-2023-036)the Key Scientific Research Foundation of the Education Department of Anhui Province(2023AH050113)the Start-up Grant from Anhui University。
文摘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.
基金financially supported by the National Key R&D Program of China(2022YFA1503003)the National Natural Science Foundation of China(91961111,22271081)+3 种基金the Natural Science Foundation of Heilongjiang Province(ZD2021B003)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2020004)The Basic Research Fund of Heilongjiang University in Heilongjiang Province(2021-KYYWF-0039)the Heilongjiang University Excellent Youth Foundation。
文摘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.
基金supported by the National Natural Science Foundation of China (U1663228 and 21473090)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Metal nitrides are widely studied due to their outstanding physical properties, including high hardness,high thermal and chemical stability, low electrical resistivity etc. Generally, metal nitrides can be obtained from the direct reaction of metal and ammonia/nitrogen. However, some of the metal nitrides,such as Ta_3N_5, cannot be synthesized by direct nitridation of metals. To achieve Ta_3N_5, high-oxidationstate Ta precursors like Ta_2O_5, NaTaO_3, TaS_3, K_6Ta_(10.8)O_(30), Ta(N(CH_3)_2)_5 and TaCl_5 have to be employed,which is a time-consuming and laborious process with the possibility of introducing undesirable impurities. Here taking Ta_3N_5 as an example, a facile carbonate-assisted one-step nitridation method is proposed, which enables the direct synthesis of high-oxidation-state metal nitride films from metal precursors under ammonia flow. The mechanism of the nitridation process has been studied, which carbon dioxide released from carbonates decomposition reacts with metallic Ta and assists the one-step conversion of metallic Ta to Ta_3N_5. The as-prepared Ta_3N_5 film, after modified with NiFe layered double hydroxide, exhibits promising water splitting performance and stability. This method avoids the preoxidation process of metal precursors in high-oxidation-state metal nitride synthesis, and may facilitate the direct fabrication of other important metal nitrides besides Ta_3N_5.
基金supported by the National Natural Science Foundation of China(Nos.51601163,22001081,and 22075236)the Natural Science Foundation of Fujian Province(No.2021J011211)+1 种基金the Xiamen Municipal Bureau of Science and Technology(No.3502Z20206070)the Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications(No.fma2018012),and Xiamen University.
文摘Ni-based transition metal nitrides(TMNs)have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction(HER)due to their low cost,excellent chemical stability,high electronic conductivity,and unique electronic structure.However,facile green synthesis and rational microstructure design of Ni-based TMNs electrocatalysts with high HER activity remain challenging.In this work,we report the fabrication of Ni/Ni_(3)N heterostructure nanoarrays on carbon paper via a one-step magnetron sputtering method under low temperature and N2 atmosphere.The Ni/Ni_(3)N hierarchical nanoarrays exhibit an excellent HER catalytic activity with a low overpotential of 37 mV at 10 mA·cm^(−2)and robust long-term durability over 100 h.Furthermore,the Ni/Ni_(3)N||NiFeOH(NiFeOH=NiFe bimetallic hydroxide)electrolyzer requires a small voltage of 1.54 V to obtain 10 mA·cm^(−2)for water electrolysis.Density functional theory(DFT)calculations reveal that the heterointerface between Ni and Ni_(3)N could directly induce electron redistribution to optimize the electronic structure,which accelerates the dissociation of water molecules and the subsequent hydrogen desorption,and thus boosting the HER kinetics.
基金Project(51274248) supported by the National Natural Science Foundation of ChinaProjects(2015DFR50580,2013DFA31440) supported by the International Scientific and Technological Cooperation Projects of China
文摘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.
基金the National Natural Science Foundation of China(Nos.51702137,51802128)the Natural Science Foundation of Jiangsu Province,China(No.BK20181013)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(No.18KJB430013)the Foundation of State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering,China(No.2020-KF-20).
文摘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).
基金This work was supported by Research Foundation of Key Laboratory of Neutron Physics(Grant No.2015BB03)National Natural Science Foundation of China(Grant Nos.11774247 and 21301122)+2 种基金Science Foundation for Excellent Youth Scholars of Sichuan University(Grant No.2015SCU04A04)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20130181120116)Premier Research Institution for Ultrahigh-pressure Sciences(PRIUS).
文摘High-pressure solid-state metathesis(HPSSM)reaction is an effective route to novel metal nitrides.A recent advance in HPSSM reactions is presented for a number of examples,including 3d transition metal nitrides(ε-Fe_(3)N,ε-Fe_(3-x)Co_(x)N,CrN,and Co_(4)N_(x)),4d transition metal nitrides(MoNx),and 5d transition metal nitrides(Re_(3)N,WN_(x)).Thermodynamic investigations based on density functional theory(DFT)calculations on several typical HPSSM reactions between metal oxides and boron nitride indicate that the pressure could reduce the reaction enthalpy △H.High-pressure confining environment thermodynamically favors an ion-exchange process between metal atom and boron atom,and successfully results in the formation of well-crystalized metal nitrides with potential applications.
基金supported by the National Natural Science Foundation of China(22072107,21872105)the Science&Technology Commission of Shanghai Municipality(19DZ2271500)the Fundamental Research Funds for the Central Universities。
文摘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.
基金financial support from the National Key Research and Development Program of China(2017YFB0102900)
文摘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.
