Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to i...Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.展开更多
The electrochemical nitrogen reduction reaction(NRR)to directly produce NH3 from N_(2) and H_(2)O under ambient conditions has attracted significant attention due to its ecofriendliness.Nevertheless,the electrochemica...The electrochemical nitrogen reduction reaction(NRR)to directly produce NH3 from N_(2) and H_(2)O under ambient conditions has attracted significant attention due to its ecofriendliness.Nevertheless,the electrochemical NRR presents several practical challenges,including sluggish reaction and low selectivity.Here,bi-atom catalysts have been proposed to achieve excellent activity and high selectivity toward the electrochemical NRR by Ma and his co-workers.It could accelerate the kinetics of N_(2)-to-NH_(3) electrochemical conversion and possess better electrochemical NRR selectivity.This work sheds light on the introduction of bi-atom catalysts to enhance the performance of the electrochemical NRR.展开更多
Gas-involved electrochemical reactions provide feasible solutions to the worldwide energy crisis and environmental pollution.It has been recognized that various elements of the reaction system,including catalysts,inte...Gas-involved electrochemical reactions provide feasible solutions to the worldwide energy crisis and environmental pollution.It has been recognized that various elements of the reaction system,including catalysts,intermediates,and products,will undergo real-time variations during the reaction process,which are of significant meaning to the in-depth understanding of reaction mechanisms,material structure,and active sites.As judicious tools for real-time monitoring of the changes in these complex elements,in situ techniques have been exposed to the spotlight in recent years.This review aims to highlight significant progress of various advanced in situ characterization techniques,such as in situ X-ray based technologies,in situ spectrum technologies,and in situ scanning probe technologies,that enhance our understanding of heterogeneous electrocatalytic carbon dioxide reduction reaction,nitrogen reduction reaction,and hydrogen evolution reaction.We provide a summary of recent advances in the development and applications of these in situ characterization techniques,from the working principle and detection modes to detailed applications in different reactions,along with key questions that need to be addressed.Finally,in view of the unique application and limitation of different in situ characterization techniques,we conclude by putting forward some insights and perspectives on the development direction and emerging combinations in the future.展开更多
The nitrogen cycle plays an important role in nature,but N-containing products cannot meet human needs.The electrochemical synthesis of ammonia under ambient conditions has attracted the interest of many researchers b...The nitrogen cycle plays an important role in nature,but N-containing products cannot meet human needs.The electrochemical synthesis of ammonia under ambient conditions has attracted the interest of many researchers because it provides a clean and pollution-free synthesis method;however,it has certain difficulties,including a high activation energy,multiple electron transfer,and hydrogenation.Thermodynamic factors limit the selectivity and activity of ammonia synthesis techniques.This review summarizes progress in the electrochemical synthesis of ammonia from theory and experiment.Theoretically,the reduction of nitrogen molecules is analyzed using orbit theory and the thermodynamic reaction pathways.Experimentally,we first discuss the effect of the experimental setup on the nitrogen reduction reaction,and then the four critical of catalysts,including size,electronic,coordination,and orientation effects.These issues must be considered to produce highly-efficient catalysts for electrochemical nitrogen reduction(eNRR).This review provides an overview of the eNRR to enable future researchers to design rational catalysts.展开更多
Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is...Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is vital to improve the kinetics of ammonia synthesis and obtain a less energy-intensive process.Herein,carbon-encapsulated mixed-valence Fe_(7)(PO_(4))_(6) was prepared and applied as an electrocatalyst for high-efficiency NRR.A dramatic faradaic efficiency(FE)of 36.93%and an NH_(3) production rate of 13.1μg h^(-1) mg_(cat)^(-1) were obtained at-0.3 V versus RHE,superior to nearly all Fe-based catalysts.Experiments and DFT calculations revealed that the superior performance was ascribed to the synergistic effect of mixed-valence iron pair,which braked the linear correlations to improve the kinetics of ammonia from collaborative hydrogenation and*NH_(3) separation.This work proves the feasibility of mixedvalence catalysts for nitrogen reduction and thus opening a new avenue towards artificial nitrogenfixation catalysts.展开更多
Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacanc...Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.展开更多
Single atom catalysts(SACs)are constituted by isolated active metal centers,which are heterogenized on inert supports such as graphene,porous carbon,and amorphous carbon.The thermal stability,electronic properties,and...Single atom catalysts(SACs)are constituted by isolated active metal centers,which are heterogenized on inert supports such as graphene,porous carbon,and amorphous carbon.The thermal stability,electronic properties,and catalytic activities of the metal center can be controlled via manipulating the neighboring heteroatoms such as nitrogen,oxygen,and sulfur.Due to the atomical dispersion of the active catalytic centers,the amount of metal required for catalysis can be decreased.Furthermore,new possibilities are offered to easily control the selectivity of a given transformation process as well as to improve turnover frequencies and turnover numbers of target reactions.Among them,Fe–N–C single atom catalysts own special electronic structure,and have been widely used in many fields of electrocatalysis.This review aims to summarize the synthesis of Fe–N–C based on anchoring individual iron atoms on carbon/graphene.The spin-related properties of Fe–N–C catalysts are described,including the relation between spin and electron structure of Fe–N x as well as the coupling between electronic structure of Fe–N x and electronic(orbit)of CO_(2),N_(2)and O_(2).Next,mechanistic investigations conducted to un-derstand the specific behavior of Fe–N–C catalysts are highlighted,including C,N,O electro-reduction.Finally,some issues related to the future developments of Fe–N–C are put forward and corresponding feasible solutions are offered.展开更多
Ammonia is the most basic raw material in industrial and agricultural production.The current industrial production of ammonia relies on the Haber-Bosch process with high energy consumption.To overcome this shortcoming...Ammonia is the most basic raw material in industrial and agricultural production.The current industrial production of ammonia relies on the Haber-Bosch process with high energy consumption.To overcome this shortcoming,the development of electrocatalytic ammonia synthesis under moderate conditions is considered as a potential alternative technology.The two-dimensional(2D)MXenes family has been proved promising as electrocatalysts,but from the currently available literature,it is hard to find a systematic review on MXenes-catalyzed ammonia synthesis.So in the present review,we summarize the key perspectives on that topic in recent years as well as outline,from a prospective view,strategies of catalyst design.We analyze in detail the methods for preparing high performance MXenes-based catalysts and the corresponding underlying mechanisms,and also discuss the criteria and potential challenges,expecting to provide inspiration for the development of efficient MXenes-based route to electrochemical ammonia fixation.展开更多
Electrochemical nitrogen reduction reaction(NRR)paves a new way to cost-efficient production of ammonia,but is still challenging in the sluggish kinetics caused by hydrogen evolution reaction competition and chemical ...Electrochemical nitrogen reduction reaction(NRR)paves a new way to cost-efficient production of ammonia,but is still challenging in the sluggish kinetics caused by hydrogen evolution reaction competition and chemical inertness of N≡N bond.Herein,we report a“dual-site”strategy for boosting NRR performance.A high-performance catalyst is successfully constructed by anchoring isolated Fe and Mo atoms on hierarchical N doped carbon nanotubes through a facile self-sacrificing template route,which exhibits a remarkably improved NH3 yield rate of 26.8μg·h^(−1)·mg with 11.8%Faradaic efficiency,which is 2.5 and 1.6 times larger than those of Fe/NC and Mo/NC.The enhancement can be attributed to the unique hierarchical structure that profits from the contact of electrode and electrolyte,thus improving the mass and electron transport.More importantly,the in situ Fourier transform infrared spectroscopy(in situ FTIR)result firmly demonstrates the crucial role of the coupling of Fe and Mo atoms,which can efficiently boost the generation and transmission of*N2Hy intermediates,leading to an accelerated reaction rate.展开更多
The Haber-Bosch process is the most widely used synthetic ammonia technology at present.Since its invention,it has provided an important guarantee for global food security.However,the traditional Haber-Bosch ammonia s...The Haber-Bosch process is the most widely used synthetic ammonia technology at present.Since its invention,it has provided an important guarantee for global food security.However,the traditional Haber-Bosch ammonia synthesis process consumes a lot of energy and causes serious environmental pollution.Under the serious pressure of energy and environment,a green,clean,and sustainable ammonia synthesis route is urgently needed.Electrochemical synthesis of ammonia is a green and mild new method for preparing ammonia,which can directly convert nitrogen or nitrate into ammonia using electricity driven by solar,wind,or water energy,without greenhouse gas and toxic gas emissions.Herein,the basic mechanism of the nitrogen reduction reaction(NRR)to ammonia and nitrate reduction reaction(NO_(3)^(-))to ammonia were discussed.The representative approaches and major technologies,such as lithium mediated electrolysis and solid oxide electrolysis cell(SOEC)electrolysis for NRR,high activity catalyst and advanced electrochemical device fabrication for(NO_(3)^(-))RR and electrochemical ammonia synthesis were summarized.Based on the above discussion and analysis,the main challenges and development directions for electrochemical ammonia synthesis were further proposed.展开更多
Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been p...Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been proposed for green ammonia synthesis from renewable electricity, air and water, where well-known defect-laden WO_(3) is used as the working electrode, and a commercially available PV panel supplies renewable electricity. In this demonstrator, defect-laden WO_(3) exhibits the optimum electrochemical NH_(3) formation rate(4.51 × 10^(-12)mol s^(-1)cm^(-2)) in 0.1 M K_(2)SO_(4)in a photovoltaic electrochemical(PV-EC) system. A system-level energy and cost analysis was conducted to investigate its economic viability and a general evaluation tool for system performance and cost estimation was proposed. This advance enables the possibility of integrating the small-scale green ammonia demonstrator into a stand-alone farm system.展开更多
Electrochemical fixation of nitrogen to ammonia with highly active,highly selective and low cost electrocatalysts is a sustainable alternative to the extremely energy-and capital-intensive Haber-Bosch process.Herein,w...Electrochemical fixation of nitrogen to ammonia with highly active,highly selective and low cost electrocatalysts is a sustainable alternative to the extremely energy-and capital-intensive Haber-Bosch process.Herein,we demonstrate a near electroneutral WO3 nanobelt catalyst to be a promising electrocatalyst for selective and efficient nitrogen reduction.The concept of near electroneutral interface is demonstrated by fabricating WO3 nanobelts with small zeta potential value on carbon fiber paper,which ensures a loose double layer structure of the electrode/electrolyte interface and allows nitrogen molecules access the active sites more easily and regulates proton transfer to increase the catalytic selectivity.The WO3/CFP electrode with optimal surface charge achieves a NH3 yield rate of 4.3μg·h-1·mg-1 and a faradaic efficiency of 37.3%at-0.3 V vs.RHE,rivalling the performance of the state-of-the-art nitrogen reduction reaction electrocatalysts.The result reveals that an unobstructed gas-diffusion pathway for continually supplying enough nitrogen to the active catalytic sites is of great importance to the overall catalytic performance.展开更多
Ammonia(NH3)is a cornerstone widely used in the modern agriculture and industry,the annual global production gradually increases to almost 200 million tons.Nearly 80%of the produced NH3 is used in the fertilizer indus...Ammonia(NH3)is a cornerstone widely used in the modern agriculture and industry,the annual global production gradually increases to almost 200 million tons.Nearly 80%of the produced NH3 is used in the fertilizer industry and is essential for the development of global agriculture and consequently for maintaining population growth.Furthermore,NH3 can power hydrogen(H2)fueled devices,such as H2 fuel cells(FC),to use the interconversion between chemical energy and electric energy of nitrogen(N2)cycle,which can effectively alleviate the intermittent problems of renewable energy.However,the problems faced by NH3 in storage and release still restrict its development.Herein,this review introduces the latest research and development of electrochemical NH3 synthesis and direct NH3 FC,as well as outlines the technical challenges,possible improvement measures and development perspectives.N2 reduction reaction(NRR)and nitrate reduction reaction(NO3RR)are two potential approaches for electrochemical NH3 synthesis.However,the existing research foundation still faces challenges in achieving high selectivity and efficiency.Direct NH3 FC are easy to transport and are expected to be widely used in mobile energy consuming equipment,but also limited by the lack of highly active and stable NH3 oxidation electrocatalysts.The perspectives of ammonia fuel cells as an alternative green energy are discussed.展开更多
Electrochemical nitrogen reduction reaction(NRR)is a promising method for the synthesis of ammonia(NH3).However,the electrochemical NRR process remains a great challenge in achieving a high NH3 yield rate and a high F...Electrochemical nitrogen reduction reaction(NRR)is a promising method for the synthesis of ammonia(NH3).However,the electrochemical NRR process remains a great challenge in achieving a high NH3 yield rate and a high Faradaic efficiency(FE)due to the extremely strong N≡N bonds and the competing hydrogen evolution reaction(HER).Recently,bismuth telluride(Bi_(2)Te_(3))with two-dimensional layered structure has been reported as a promising catalyst for N_(2)fixation.Herein,to further enhance its NRR activity,a general doping strategy is developed to introduce and modulate the crystal defects of Bi_(2)Te_(3)nanosheets by adjusting the amount of Ce dopant(denoted as Ce_(x)-Bi_(2)Te_(3),where x represents the designed molar ratio of Ce/Bi).Meanwhile,the crystal defects can be designed and controlled by means of ion substitution and charge compensation.At−0.60 V versus the reversible hydrogen electrode(RHE),Ce_(0.3)-Bi_(2)Te_(3)exhibits a high NH_(3) yield(78.2μg·h^(−1)·mgcat^(−1)),a high FE(19.3%),excellent structural and electrochemical stability.Its outstanding catalytic activity is attributed to the tunable crystal defects by Ce doping.This work not only contributes to enhancing the NRR activity of Bi_(2)Te_(3)nanosheets,but also provides a reliable approach to prepare high-performance electrocatalysts by controlling the type and concentration of crystal defects for artificial N_(2)fixation.展开更多
Electrochemical nitrogen reduction reaction(NRR)is considered as an alternative to the industrial Haber-Bosch process for NH3 production due to both low energy consumption and environment friendliness.However,the majo...Electrochemical nitrogen reduction reaction(NRR)is considered as an alternative to the industrial Haber-Bosch process for NH3 production due to both low energy consumption and environment friendliness.However,the major problem of electrochemical NRR is the unsatisfied efficiency and selectivity of electrocatalyst.As one group of the cheapest and most abundant transition metals,iron-group(Fe,Co,Ni and Cu)electrocatalysts show promising potential on cost and performance advantages as ideal substitute for traditional noble-metal catalysts.In this minireview,we summarize recent advances of iron-group-based materials(including their oxides,hydroxides,nitrides,sulfides and phosphides,etc.)as non-noble metal electrocatalysts towards ambient N2-to-NH3 conversion in aqueous media.Strategies to boost NRR performances and perspectives for future developments are discussed to provide guidance for the field of NRR studies.展开更多
To perform the electrochemical nitrogen reduction reaction(NRR)under milder conditions for sustainable ammonia production,electrocatalysts should exhibit high selectivity,activity,and durability.However,the key restri...To perform the electrochemical nitrogen reduction reaction(NRR)under milder conditions for sustainable ammonia production,electrocatalysts should exhibit high selectivity,activity,and durability.However,the key restrictions are the highly stable N≡N triple bond and the competitive hydrogen evolution reaction(HER),which make it difficult to adsorb and activate N2 on the surface of electrocatalysts,leading to a low ammonia yield and Faraday efficiency.Inspired by the enzymatic nitrogenase process and using the Fe-Mo as the active center,here we report supported Fe_(2)Mo_(3)O_(8)/XC-72 as an effective and durable electrocatalyst for the NRR.Fe_(2)Mo_(3)O_(8)/XC-72 exhibited NRR activity with an NH3 yield of 30.4μg·h^(−1)·mg^(−1)(−0.3 V)and a Faraday efficiency of 8.2%(−0.3 V).Theoretical calculations demonstrated that the electrocatalytic nitrogen fixation mechanism involved the Fe atom in the Fe_(2)Mo_(3)O_(8)/XC-72 electrocatalyst acting as the main active site in the enzymatic pathway(*NH2→*NH3),which activated nitrogen molecules and promoted the NRR performance.展开更多
基金supported by the Climate Change Response Project (NRF-2019M1A2A2065612)the Brainlink Project (NRF2022H1D3A3A01081140)+3 种基金the NRF-2021R1A4A3027878 and the No. RS-2023-00212273 funded by the Ministry of Science and ICT of Korea via National Research Foundationresearch funds from Hanhwa Solutions Chemicals (1.220029.01)UNIST (1.190013.01)supported by the Institute for Basic Science (IBS-R019-D1)。
文摘Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.
文摘The electrochemical nitrogen reduction reaction(NRR)to directly produce NH3 from N_(2) and H_(2)O under ambient conditions has attracted significant attention due to its ecofriendliness.Nevertheless,the electrochemical NRR presents several practical challenges,including sluggish reaction and low selectivity.Here,bi-atom catalysts have been proposed to achieve excellent activity and high selectivity toward the electrochemical NRR by Ma and his co-workers.It could accelerate the kinetics of N_(2)-to-NH_(3) electrochemical conversion and possess better electrochemical NRR selectivity.This work sheds light on the introduction of bi-atom catalysts to enhance the performance of the electrochemical NRR.
基金supported by The National Natural Science Foundation of China(Nos.U21A20332,52103226,and 52071226)The Outstanding Youth Foundation of Jiangsu Province(No.BK20220061)+2 种基金The Natural Science Foundation of Jiangsu Province(No.BK20201171)The Key Research and Development Plan of Jiangsu Province(No.BE2020003-3)The Fellowship of China Postdoctoral Science Foundation(No.2021M702382).
文摘Gas-involved electrochemical reactions provide feasible solutions to the worldwide energy crisis and environmental pollution.It has been recognized that various elements of the reaction system,including catalysts,intermediates,and products,will undergo real-time variations during the reaction process,which are of significant meaning to the in-depth understanding of reaction mechanisms,material structure,and active sites.As judicious tools for real-time monitoring of the changes in these complex elements,in situ techniques have been exposed to the spotlight in recent years.This review aims to highlight significant progress of various advanced in situ characterization techniques,such as in situ X-ray based technologies,in situ spectrum technologies,and in situ scanning probe technologies,that enhance our understanding of heterogeneous electrocatalytic carbon dioxide reduction reaction,nitrogen reduction reaction,and hydrogen evolution reaction.We provide a summary of recent advances in the development and applications of these in situ characterization techniques,from the working principle and detection modes to detailed applications in different reactions,along with key questions that need to be addressed.Finally,in view of the unique application and limitation of different in situ characterization techniques,we conclude by putting forward some insights and perspectives on the development direction and emerging combinations in the future.
基金financially supported by the Beijing Municipal High Level Innovative Team Building Program(No.IDHT20180504)the Beijing Outstanding Young Scientist Program(BJJWZYJH01201910005017)+5 种基金the National Natural Science Foundation of China(No.51801006,21805004,21671011 and 21872001)the Beijing Natural Science Foundation(No.KZ201710005002 and 2192005)the Beijing Municipal Science and Natural Science Fund Project(No.KM201910005016)the China Postdoctoral Science Foundation(No.2018M641133)the Beijing Postdoctoral Research Foundation(No.2018-ZZ-021)the Chaoyang District Postdoctoral Research Foundation(No.2018-ZZ-026)。
文摘The nitrogen cycle plays an important role in nature,but N-containing products cannot meet human needs.The electrochemical synthesis of ammonia under ambient conditions has attracted the interest of many researchers because it provides a clean and pollution-free synthesis method;however,it has certain difficulties,including a high activation energy,multiple electron transfer,and hydrogenation.Thermodynamic factors limit the selectivity and activity of ammonia synthesis techniques.This review summarizes progress in the electrochemical synthesis of ammonia from theory and experiment.Theoretically,the reduction of nitrogen molecules is analyzed using orbit theory and the thermodynamic reaction pathways.Experimentally,we first discuss the effect of the experimental setup on the nitrogen reduction reaction,and then the four critical of catalysts,including size,electronic,coordination,and orientation effects.These issues must be considered to produce highly-efficient catalysts for electrochemical nitrogen reduction(eNRR).This review provides an overview of the eNRR to enable future researchers to design rational catalysts.
基金supported by the National Natural Science Foundation of China(21908120 and 22109078)the Youth Innovation Team Project of Shandong Provincial Education Department(2019KJC023)。
文摘Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is vital to improve the kinetics of ammonia synthesis and obtain a less energy-intensive process.Herein,carbon-encapsulated mixed-valence Fe_(7)(PO_(4))_(6) was prepared and applied as an electrocatalyst for high-efficiency NRR.A dramatic faradaic efficiency(FE)of 36.93%and an NH_(3) production rate of 13.1μg h^(-1) mg_(cat)^(-1) were obtained at-0.3 V versus RHE,superior to nearly all Fe-based catalysts.Experiments and DFT calculations revealed that the superior performance was ascribed to the synergistic effect of mixed-valence iron pair,which braked the linear correlations to improve the kinetics of ammonia from collaborative hydrogenation and*NH_(3) separation.This work proves the feasibility of mixedvalence catalysts for nitrogen reduction and thus opening a new avenue towards artificial nitrogenfixation catalysts.
基金financially supported by the National Key Research and Development Program of China(2017YFA0206500)NSFC(Grant Nos.21673198,91934303,21621091)。
文摘Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.
基金We are grateful for the financial support from National Natural Sci-ence Foundation of China(No.21974103)and the start-up funds of Wuhan University.
文摘Single atom catalysts(SACs)are constituted by isolated active metal centers,which are heterogenized on inert supports such as graphene,porous carbon,and amorphous carbon.The thermal stability,electronic properties,and catalytic activities of the metal center can be controlled via manipulating the neighboring heteroatoms such as nitrogen,oxygen,and sulfur.Due to the atomical dispersion of the active catalytic centers,the amount of metal required for catalysis can be decreased.Furthermore,new possibilities are offered to easily control the selectivity of a given transformation process as well as to improve turnover frequencies and turnover numbers of target reactions.Among them,Fe–N–C single atom catalysts own special electronic structure,and have been widely used in many fields of electrocatalysis.This review aims to summarize the synthesis of Fe–N–C based on anchoring individual iron atoms on carbon/graphene.The spin-related properties of Fe–N–C catalysts are described,including the relation between spin and electron structure of Fe–N x as well as the coupling between electronic structure of Fe–N x and electronic(orbit)of CO_(2),N_(2)and O_(2).Next,mechanistic investigations conducted to un-derstand the specific behavior of Fe–N–C catalysts are highlighted,including C,N,O electro-reduction.Finally,some issues related to the future developments of Fe–N–C are put forward and corresponding feasible solutions are offered.
基金supports from ETH board,Empa internal research call 2019(IRC-2019-CupSupercap)and 2020(IRC-2020-NitfixMX)supports from Xi'an Jiaotong University,and China Scholarship Council(202106280247).
文摘Ammonia is the most basic raw material in industrial and agricultural production.The current industrial production of ammonia relies on the Haber-Bosch process with high energy consumption.To overcome this shortcoming,the development of electrocatalytic ammonia synthesis under moderate conditions is considered as a potential alternative technology.The two-dimensional(2D)MXenes family has been proved promising as electrocatalysts,but from the currently available literature,it is hard to find a systematic review on MXenes-catalyzed ammonia synthesis.So in the present review,we summarize the key perspectives on that topic in recent years as well as outline,from a prospective view,strategies of catalyst design.We analyze in detail the methods for preparing high performance MXenes-based catalysts and the corresponding underlying mechanisms,and also discuss the criteria and potential challenges,expecting to provide inspiration for the development of efficient MXenes-based route to electrochemical ammonia fixation.
基金supported by the financial aid from National Science and Technology Major Project of China(No.2021YFB3500700)National Natural Science Foundation of China(Nos.22020102003,22025506,and 22271274)+2 种基金Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-3-3)K.C.Wong Education Foundation(No.GJTD-2018-09)Innovation and Entrepreneurship Program of Jilin Province(No.E2390202).
文摘Electrochemical nitrogen reduction reaction(NRR)paves a new way to cost-efficient production of ammonia,but is still challenging in the sluggish kinetics caused by hydrogen evolution reaction competition and chemical inertness of N≡N bond.Herein,we report a“dual-site”strategy for boosting NRR performance.A high-performance catalyst is successfully constructed by anchoring isolated Fe and Mo atoms on hierarchical N doped carbon nanotubes through a facile self-sacrificing template route,which exhibits a remarkably improved NH3 yield rate of 26.8μg·h^(−1)·mg with 11.8%Faradaic efficiency,which is 2.5 and 1.6 times larger than those of Fe/NC and Mo/NC.The enhancement can be attributed to the unique hierarchical structure that profits from the contact of electrode and electrolyte,thus improving the mass and electron transport.More importantly,the in situ Fourier transform infrared spectroscopy(in situ FTIR)result firmly demonstrates the crucial role of the coupling of Fe and Mo atoms,which can efficiently boost the generation and transmission of*N2Hy intermediates,leading to an accelerated reaction rate.
文摘The Haber-Bosch process is the most widely used synthetic ammonia technology at present.Since its invention,it has provided an important guarantee for global food security.However,the traditional Haber-Bosch ammonia synthesis process consumes a lot of energy and causes serious environmental pollution.Under the serious pressure of energy and environment,a green,clean,and sustainable ammonia synthesis route is urgently needed.Electrochemical synthesis of ammonia is a green and mild new method for preparing ammonia,which can directly convert nitrogen or nitrate into ammonia using electricity driven by solar,wind,or water energy,without greenhouse gas and toxic gas emissions.Herein,the basic mechanism of the nitrogen reduction reaction(NRR)to ammonia and nitrate reduction reaction(NO_(3)^(-))to ammonia were discussed.The representative approaches and major technologies,such as lithium mediated electrolysis and solid oxide electrolysis cell(SOEC)electrolysis for NRR,high activity catalyst and advanced electrochemical device fabrication for(NO_(3)^(-))RR and electrochemical ammonia synthesis were summarized.Based on the above discussion and analysis,the main challenges and development directions for electrochemical ammonia synthesis were further proposed.
基金grateful to the Natural Sciences and Engineering Council of Canada for supportthe Nation Natural Science Foundation of China (NSFC 21878162,21872102)+4 种基金support of the NSFC(52102311)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2019ZT08L101)the Special Fund for the Sci-tech Innovation Strategy of Guangdong Province(210629095860472)the Shenzhen Natural Science Foundation(GXWD20201231105722002-20200824163747001)the Shenzhen Key Laboratory of Eco-materials and Renewable Energy(ZDSYS20200922160400001)。
文摘Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been proposed for green ammonia synthesis from renewable electricity, air and water, where well-known defect-laden WO_(3) is used as the working electrode, and a commercially available PV panel supplies renewable electricity. In this demonstrator, defect-laden WO_(3) exhibits the optimum electrochemical NH_(3) formation rate(4.51 × 10^(-12)mol s^(-1)cm^(-2)) in 0.1 M K_(2)SO_(4)in a photovoltaic electrochemical(PV-EC) system. A system-level energy and cost analysis was conducted to investigate its economic viability and a general evaluation tool for system performance and cost estimation was proposed. This advance enables the possibility of integrating the small-scale green ammonia demonstrator into a stand-alone farm system.
基金supported by Shenzhen Science and Technology Research Grant(ZDSYS201707281026184)Natural Science Foundation of Shenzhen(JCYJ20190813110605381)。
文摘Electrochemical fixation of nitrogen to ammonia with highly active,highly selective and low cost electrocatalysts is a sustainable alternative to the extremely energy-and capital-intensive Haber-Bosch process.Herein,we demonstrate a near electroneutral WO3 nanobelt catalyst to be a promising electrocatalyst for selective and efficient nitrogen reduction.The concept of near electroneutral interface is demonstrated by fabricating WO3 nanobelts with small zeta potential value on carbon fiber paper,which ensures a loose double layer structure of the electrode/electrolyte interface and allows nitrogen molecules access the active sites more easily and regulates proton transfer to increase the catalytic selectivity.The WO3/CFP electrode with optimal surface charge achieves a NH3 yield rate of 4.3μg·h-1·mg-1 and a faradaic efficiency of 37.3%at-0.3 V vs.RHE,rivalling the performance of the state-of-the-art nitrogen reduction reaction electrocatalysts.The result reveals that an unobstructed gas-diffusion pathway for continually supplying enough nitrogen to the active catalytic sites is of great importance to the overall catalytic performance.
基金support from Suzhou Foreign Academician Workstation(SWY2021002)National Natural Science Foundation of China(No.22202144)Collaborative Innovation Center of Water Treatment Technology and Material,and Innovation Platform for Academicians of Hainan Province.
文摘Ammonia(NH3)is a cornerstone widely used in the modern agriculture and industry,the annual global production gradually increases to almost 200 million tons.Nearly 80%of the produced NH3 is used in the fertilizer industry and is essential for the development of global agriculture and consequently for maintaining population growth.Furthermore,NH3 can power hydrogen(H2)fueled devices,such as H2 fuel cells(FC),to use the interconversion between chemical energy and electric energy of nitrogen(N2)cycle,which can effectively alleviate the intermittent problems of renewable energy.However,the problems faced by NH3 in storage and release still restrict its development.Herein,this review introduces the latest research and development of electrochemical NH3 synthesis and direct NH3 FC,as well as outlines the technical challenges,possible improvement measures and development perspectives.N2 reduction reaction(NRR)and nitrate reduction reaction(NO3RR)are two potential approaches for electrochemical NH3 synthesis.However,the existing research foundation still faces challenges in achieving high selectivity and efficiency.Direct NH3 FC are easy to transport and are expected to be widely used in mobile energy consuming equipment,but also limited by the lack of highly active and stable NH3 oxidation electrocatalysts.The perspectives of ammonia fuel cells as an alternative green energy are discussed.
基金the National Natural Science Foundation of China(Nos.22074137 and 21721003).
文摘Electrochemical nitrogen reduction reaction(NRR)is a promising method for the synthesis of ammonia(NH3).However,the electrochemical NRR process remains a great challenge in achieving a high NH3 yield rate and a high Faradaic efficiency(FE)due to the extremely strong N≡N bonds and the competing hydrogen evolution reaction(HER).Recently,bismuth telluride(Bi_(2)Te_(3))with two-dimensional layered structure has been reported as a promising catalyst for N_(2)fixation.Herein,to further enhance its NRR activity,a general doping strategy is developed to introduce and modulate the crystal defects of Bi_(2)Te_(3)nanosheets by adjusting the amount of Ce dopant(denoted as Ce_(x)-Bi_(2)Te_(3),where x represents the designed molar ratio of Ce/Bi).Meanwhile,the crystal defects can be designed and controlled by means of ion substitution and charge compensation.At−0.60 V versus the reversible hydrogen electrode(RHE),Ce_(0.3)-Bi_(2)Te_(3)exhibits a high NH_(3) yield(78.2μg·h^(−1)·mgcat^(−1)),a high FE(19.3%),excellent structural and electrochemical stability.Its outstanding catalytic activity is attributed to the tunable crystal defects by Ce doping.This work not only contributes to enhancing the NRR activity of Bi_(2)Te_(3)nanosheets,but also provides a reliable approach to prepare high-performance electrocatalysts by controlling the type and concentration of crystal defects for artificial N_(2)fixation.
文摘Electrochemical nitrogen reduction reaction(NRR)is considered as an alternative to the industrial Haber-Bosch process for NH3 production due to both low energy consumption and environment friendliness.However,the major problem of electrochemical NRR is the unsatisfied efficiency and selectivity of electrocatalyst.As one group of the cheapest and most abundant transition metals,iron-group(Fe,Co,Ni and Cu)electrocatalysts show promising potential on cost and performance advantages as ideal substitute for traditional noble-metal catalysts.In this minireview,we summarize recent advances of iron-group-based materials(including their oxides,hydroxides,nitrides,sulfides and phosphides,etc.)as non-noble metal electrocatalysts towards ambient N2-to-NH3 conversion in aqueous media.Strategies to boost NRR performances and perspectives for future developments are discussed to provide guidance for the field of NRR studies.
基金support from the Beijing Municipal High Level Innovative Team Building Program(No.IDHT20180504)Beijing Outstanding Young Scientist Program(No.BJJWZYJH01201910005017)+2 种基金the National Natural Science Foundation of China(Nos.51801006,21805004,21872001,and 21936001)Beijing Natural Science Foundation(No.2192005)Beijing Municipal Science and Natural Science Fund Project(Nos.KM201910005016 and 2017000020124G085).
文摘To perform the electrochemical nitrogen reduction reaction(NRR)under milder conditions for sustainable ammonia production,electrocatalysts should exhibit high selectivity,activity,and durability.However,the key restrictions are the highly stable N≡N triple bond and the competitive hydrogen evolution reaction(HER),which make it difficult to adsorb and activate N2 on the surface of electrocatalysts,leading to a low ammonia yield and Faraday efficiency.Inspired by the enzymatic nitrogenase process and using the Fe-Mo as the active center,here we report supported Fe_(2)Mo_(3)O_(8)/XC-72 as an effective and durable electrocatalyst for the NRR.Fe_(2)Mo_(3)O_(8)/XC-72 exhibited NRR activity with an NH3 yield of 30.4μg·h^(−1)·mg^(−1)(−0.3 V)and a Faraday efficiency of 8.2%(−0.3 V).Theoretical calculations demonstrated that the electrocatalytic nitrogen fixation mechanism involved the Fe atom in the Fe_(2)Mo_(3)O_(8)/XC-72 electrocatalyst acting as the main active site in the enzymatic pathway(*NH2→*NH3),which activated nitrogen molecules and promoted the NRR performance.