Developing efficient,low-cost non-noble metal-based bifunctional catalysts to achieve excellent hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)kinetics in alkaline media is challenging but very mean...Developing efficient,low-cost non-noble metal-based bifunctional catalysts to achieve excellent hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)kinetics in alkaline media is challenging but very meaningful.However,improving the electronic structure of the catalyst to optimize the adsorption of intermediates and reduce the reaction energy barrier is the key to improve the reaction efficiency.Herein,a V-doped Co_(2)P coupled with high-entropy MXene heterostructure catalyst(V-Co_(2)P@HE)was prepared by a two-step electrodeposition and controlled phosphorization process.The analyses of X-ray absorption spectroscopy,X-ray photoelectron spectroscopy and theoretical calculations jointly show that the introduction of V and the strong electron coupling between the two components optimize the adsorption energy of water molecules and reaction intermediates.Benefiting from the abundant active sites and optimizing intermediate adsorption energy and heterogeneous interface electronic structure,V-Co_(2)P@HE has excellent HER and OER activity and long-term stability under alkaline condition.In particular,when assembled as cathode and anode,the bifunctional V-Co_(2)P@HE catalyst can drive a current density of 10 mA cm^(-2)with only 1.53 V.This work provides new strategies for the application of highentropy MXene and the design of novel non-noble metal-based bifunctional electrolytic water catalysts.展开更多
Mg-based materials are one of the most promising hydrogen storage candidates due to their high hydrogen storage capacity,environmental benignity,and high Clarke number characteristics.However,the limited thermodynamic...Mg-based materials are one of the most promising hydrogen storage candidates due to their high hydrogen storage capacity,environmental benignity,and high Clarke number characteristics.However,the limited thermodynamics and kinetic properties pose major challenges for their engineering applications.Herein,we review the recent progress in improving their thermodynamics and kinetics,with an emphasis on the models and the influence of various parameters in the calculated models.Subsequently,the impact of alloying,composite,and nanocrystallization on both thermodynamics and dynamics are discussed in detail.In particular,the correlation between various modification strategies and the hydrogen capacity,dehydrogenation enthalpy and temperature,hydriding/dehydriding rates are summarized.In addition,the mechanism of hydrogen storage processes of Mg-based materials is discussed from the aspect of classical kinetic theories and microscope hydrogen transferring behavior.This review concludes with an outlook on the remaining challenge issues and prospects.展开更多
Reduction of titanomagnetite （TTM） powders by H2-Ar gas mixtures was investigated under a non-isothermal condition by using a thermogravimetric analysis system. It was found that non-isothermal reduction of TTM proc...Reduction of titanomagnetite （TTM） powders by H2-Ar gas mixtures was investigated under a non-isothermal condition by using a thermogravimetric analysis system. It was found that non-isothermal reduction of TTM proceeded via a dual-reaction mechanism. The first reaction was reduction of TTM to wustite and ilmenite, whereas the second one was reduction of wiistite and ilmenite to iron and titanium dioxide. By using a new model for the dual reactions, which was in an analytical form and incorporated different variables, such as time, temperature, particle size, and hydrogen partial pressure, rate-controlling steps for the dual reactions were obtained with the apparent activation energies calculated to be 90-98 and 115-132 kJ/mol for the first and second reactions, respectively.展开更多
Oxygen evolution reaction(OER)is central to technologies such as electrochemical water splitting,and developing efficient and low-cost non-precious metal electrocatalysts for OER is of great significance to reducing c...Oxygen evolution reaction(OER)is central to technologies such as electrochemical water splitting,and developing efficient and low-cost non-precious metal electrocatalysts for OER is of great significance to reducing cell voltage and developing hydrogen production by electrochemical water splitting.Herein,we prepared a carbon,nitrogen co-doped porous Co_(2)P derived from the metal-organic framework(ZIF-67),which is anchored on bimetallic MXene nanosheets(named MX@MOF-Co_(2)P).It was used as the OER catalyst and exhibited great electrocatalytic performance with very small overpotentials(246 mV at 10 mA^(-2)and 407 mV at 200 mA cm^(-2))as well as ultralow Tafel slope(28.18 mV dec^(-1)).Combining charac-terizations and theoretical calculations,it was found that the remarkable performance was from follows:the obtained MX@MOF-Co_(2)P inherited the porous structure of the pristine MOF with a large number of open active sites;carbon and nitrogen doping also modulated the electronic structure of the active center;the synergistic effect between cobalt phosphide and MXenes booted the electronic transfer.This work represents a promising strategy for the development of non-precious metal catalysts derived from metal-organic frameworks to achieve efficient energy conversion.展开更多
The exploration of novel,super-potent and low-cost electrocatalysts for water splitting has always been the kernel in the field of renewable sources.Herein,exfoliated Ti_(3)C_(2)T_(x) MXenes work as a substrate to ver...The exploration of novel,super-potent and low-cost electrocatalysts for water splitting has always been the kernel in the field of renewable sources.Herein,exfoliated Ti_(3)C_(2)T_(x) MXenes work as a substrate to vertically grow polypore N,Ni-Co2P nanoarrays(N,Ni-Co2P@TC)through an in situ interface-growth strategy and subsequent phosphorization and nitridation.The well-defined heterointerfaces with positive and negative ions co-modulation as coupled hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts for efficient overall water splitting are investigated,which possesses excellent durability even at a large current density(±500 mA cm^(-2)).For HER,suitable H_(2)O∗and H∗absorption energies and accelerated electronic transmission make N,Ni-Co2P@TC display a low overpotential of 27 mV at-10 mA cm^(-2) and Tafel slope of 38 mV dec^(–1) in 1 mol/L KOH.For OER,the synergy of N,Ni-Co2P@TC with selfreconfiguration can give enhanced activity with a low overpotential of 232 mV at 10 mA cm^(-2) and a Tafel slope of 57 mV dec^(–1).Additionally,the excellent bifunctional activity allows easily combining for efficient overall water splitting with a low driving voltage(1.51 V)at 10 mA cm^(-2),and the electrolyzer can be driven by a 1.5 V AAA battery.展开更多
High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction(HER),but developing such materials is challenging.Herein,a simple strategy was designed ...High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction(HER),but developing such materials is challenging.Herein,a simple strategy was designed to build a MoS_(2)/Co_(9)S_(8)/MoC@CNT-N(MCM@CNT-N)heterostructure with a large number of interfaces.Regarding the HER,the synthesized MCM@CNT-N heterostructure catalyst showed high efficiency and stable electrocatalytic performance,with a low overpotential of 174.2 mV and a small Tafel slope of 84.7 mV dec^(-1) at a current density of 10 mA cm^(-2) in 0.5 M H_(2)SO_(4).In addition to the function of heterojunctions,the excellent activity is also attributed to the introduction of Co and N atoms and the formation of carbon nanotubes.This work provides a new approach to build efficient and low-cost electrocatalysts for electrochemical reactions.展开更多
The methodology and procedures are discussed on designing merchant ships to achieve fully-integrated and optimized hull-propulsion systems by using asymmetric aftbodies. Computational fluid dynamics （CFD） has been u...The methodology and procedures are discussed on designing merchant ships to achieve fully-integrated and optimized hull-propulsion systems by using asymmetric aftbodies. Computational fluid dynamics （CFD） has been used to evaluate the powering performance through massive calculations with automatic deformation algorisms for the hull forms and the propeller blades. Comparative model tests of the designs to the optimized symmetric hull forms have been carried out to verify the efficiency gain. More than 6% improvement on the propulsive efficiency of an oil tanker has been measured during the model tests. Dedicated sea-trials show good agreement with the predicted performance from the test results.展开更多
基金the financial supports from the National Natural Science Foundation of China(52222408)。
文摘Developing efficient,low-cost non-noble metal-based bifunctional catalysts to achieve excellent hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)kinetics in alkaline media is challenging but very meaningful.However,improving the electronic structure of the catalyst to optimize the adsorption of intermediates and reduce the reaction energy barrier is the key to improve the reaction efficiency.Herein,a V-doped Co_(2)P coupled with high-entropy MXene heterostructure catalyst(V-Co_(2)P@HE)was prepared by a two-step electrodeposition and controlled phosphorization process.The analyses of X-ray absorption spectroscopy,X-ray photoelectron spectroscopy and theoretical calculations jointly show that the introduction of V and the strong electron coupling between the two components optimize the adsorption energy of water molecules and reaction intermediates.Benefiting from the abundant active sites and optimizing intermediate adsorption energy and heterogeneous interface electronic structure,V-Co_(2)P@HE has excellent HER and OER activity and long-term stability under alkaline condition.In particular,when assembled as cathode and anode,the bifunctional V-Co_(2)P@HE catalyst can drive a current density of 10 mA cm^(-2)with only 1.53 V.This work provides new strategies for the application of highentropy MXene and the design of novel non-noble metal-based bifunctional electrolytic water catalysts.
基金supported by the Chongqing Special Key Project of Technology Innovation and Application Development,China(cstc2019jscx-dxwt B0029)the National Natural Science Foundation of China(51871143)+5 种基金the Science and Technology Committee of Shanghai(19010500400)the Shanghai Rising-Star Program(21QA1403200)Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2019jcyj-msxm X0306)the Start-up Funds of Chongqing University(02110011044171)the Senior Talent Start-up Funds of Jiangsu University(4111310024)the Independent Research Project of State Key Laboratory of Mechanical Transmissions(SKLMT-ZZKT-2021M11)
文摘Mg-based materials are one of the most promising hydrogen storage candidates due to their high hydrogen storage capacity,environmental benignity,and high Clarke number characteristics.However,the limited thermodynamics and kinetic properties pose major challenges for their engineering applications.Herein,we review the recent progress in improving their thermodynamics and kinetics,with an emphasis on the models and the influence of various parameters in the calculated models.Subsequently,the impact of alloying,composite,and nanocrystallization on both thermodynamics and dynamics are discussed in detail.In particular,the correlation between various modification strategies and the hydrogen capacity,dehydrogenation enthalpy and temperature,hydriding/dehydriding rates are summarized.In addition,the mechanism of hydrogen storage processes of Mg-based materials is discussed from the aspect of classical kinetic theories and microscope hydrogen transferring behavior.This review concludes with an outlook on the remaining challenge issues and prospects.
基金financial support from the National Natural Science Foundation of China (No.11220158)the Fundamental Research Funds for the Central Universities (FRF-TP-13-002A)
文摘Reduction of titanomagnetite （TTM） powders by H2-Ar gas mixtures was investigated under a non-isothermal condition by using a thermogravimetric analysis system. It was found that non-isothermal reduction of TTM proceeded via a dual-reaction mechanism. The first reaction was reduction of TTM to wustite and ilmenite, whereas the second one was reduction of wiistite and ilmenite to iron and titanium dioxide. By using a new model for the dual reactions, which was in an analytical form and incorporated different variables, such as time, temperature, particle size, and hydrogen partial pressure, rate-controlling steps for the dual reactions were obtained with the apparent activation energies calculated to be 90-98 and 115-132 kJ/mol for the first and second reactions, respectively.
基金This work was financially supported by the National Natural Science Foundation of China(No.52222408)the Fok Ying Tung Education Foundation(No.171111).
文摘Oxygen evolution reaction(OER)is central to technologies such as electrochemical water splitting,and developing efficient and low-cost non-precious metal electrocatalysts for OER is of great significance to reducing cell voltage and developing hydrogen production by electrochemical water splitting.Herein,we prepared a carbon,nitrogen co-doped porous Co_(2)P derived from the metal-organic framework(ZIF-67),which is anchored on bimetallic MXene nanosheets(named MX@MOF-Co_(2)P).It was used as the OER catalyst and exhibited great electrocatalytic performance with very small overpotentials(246 mV at 10 mA^(-2)and 407 mV at 200 mA cm^(-2))as well as ultralow Tafel slope(28.18 mV dec^(-1)).Combining charac-terizations and theoretical calculations,it was found that the remarkable performance was from follows:the obtained MX@MOF-Co_(2)P inherited the porous structure of the pristine MOF with a large number of open active sites;carbon and nitrogen doping also modulated the electronic structure of the active center;the synergistic effect between cobalt phosphide and MXenes booted the electronic transfer.This work represents a promising strategy for the development of non-precious metal catalysts derived from metal-organic frameworks to achieve efficient energy conversion.
基金supported by the National Natural Science Foundation of China(No.52222408)the Fundamental Research Funds for the Central Universities(No.2020CDJGFCL004)+1 种基金the Fok Ying Tung Education Foundation(No.171111)the Joint Fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals(No.18LHPY015).
文摘The exploration of novel,super-potent and low-cost electrocatalysts for water splitting has always been the kernel in the field of renewable sources.Herein,exfoliated Ti_(3)C_(2)T_(x) MXenes work as a substrate to vertically grow polypore N,Ni-Co2P nanoarrays(N,Ni-Co2P@TC)through an in situ interface-growth strategy and subsequent phosphorization and nitridation.The well-defined heterointerfaces with positive and negative ions co-modulation as coupled hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts for efficient overall water splitting are investigated,which possesses excellent durability even at a large current density(±500 mA cm^(-2)).For HER,suitable H_(2)O∗and H∗absorption energies and accelerated electronic transmission make N,Ni-Co2P@TC display a low overpotential of 27 mV at-10 mA cm^(-2) and Tafel slope of 38 mV dec^(–1) in 1 mol/L KOH.For OER,the synergy of N,Ni-Co2P@TC with selfreconfiguration can give enhanced activity with a low overpotential of 232 mV at 10 mA cm^(-2) and a Tafel slope of 57 mV dec^(–1).Additionally,the excellent bifunctional activity allows easily combining for efficient overall water splitting with a low driving voltage(1.51 V)at 10 mA cm^(-2),and the electrolyzer can be driven by a 1.5 V AAA battery.
基金Thanks are given to the financial supports from the National Key R&D Program of China(2017YFB0603800)the Fundamental Research Funds for the Central Universities(2020CDJGFCL004)+4 种基金Fok Ying Tung Education Foundation(171111)Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)the Venture&Innovation Support Program for Chongqing Overseas Returnees(cx2019041,cx2018055)Joint fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals(18LHPY015)Thanks are also given to the support from school of chemistry and chemical engineering of Chongqing University for the DFT calculations.
文摘High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction(HER),but developing such materials is challenging.Herein,a simple strategy was designed to build a MoS_(2)/Co_(9)S_(8)/MoC@CNT-N(MCM@CNT-N)heterostructure with a large number of interfaces.Regarding the HER,the synthesized MCM@CNT-N heterostructure catalyst showed high efficiency and stable electrocatalytic performance,with a low overpotential of 174.2 mV and a small Tafel slope of 84.7 mV dec^(-1) at a current density of 10 mA cm^(-2) in 0.5 M H_(2)SO_(4).In addition to the function of heterojunctions,the excellent activity is also attributed to the introduction of Co and N atoms and the formation of carbon nanotubes.This work provides a new approach to build efficient and low-cost electrocatalysts for electrochemical reactions.
基金support from Guangzhou Shipbuilding International Company Ltd.(GSI) for the present study
文摘The methodology and procedures are discussed on designing merchant ships to achieve fully-integrated and optimized hull-propulsion systems by using asymmetric aftbodies. Computational fluid dynamics （CFD） has been used to evaluate the powering performance through massive calculations with automatic deformation algorisms for the hull forms and the propeller blades. Comparative model tests of the designs to the optimized symmetric hull forms have been carried out to verify the efficiency gain. More than 6% improvement on the propulsive efficiency of an oil tanker has been measured during the model tests. Dedicated sea-trials show good agreement with the predicted performance from the test results.
