降低催化剂中贵金属Pt含量是构建高性能析氢反应(Hydrogen evolution reaction,HER)电催化剂的关键。通过电化学沉积法将Cu纳米修饰到二维Nb_(2)CT_(x)表面,然后利用电化学置换反应制备得到二维Nb_(2)CT_(x)负载Pt纳米颗粒(PtNP/Nb_(2)C...降低催化剂中贵金属Pt含量是构建高性能析氢反应(Hydrogen evolution reaction,HER)电催化剂的关键。通过电化学沉积法将Cu纳米修饰到二维Nb_(2)CT_(x)表面,然后利用电化学置换反应制备得到二维Nb_(2)CT_(x)负载Pt纳米颗粒(PtNP/Nb_(2)CT_(x))催化剂。采用SEM、XRD和XPS等手段对所得催化剂的形貌、结构及组成进行表征,并研究了PtNP/Nb_(2)CT_(x)催化剂在酸性和中性介质中的电催化HER性能。结果表明,在10 m A·cm^(-2)电流密度下,PtNP/Nb_(2)CT_(x)催化剂在0.5 mol·L^(-1)H2SO4和1.0 mol·L^(-1)PBS电解液中的过电压分别为38 m V和146 m V,Tafel斜率分别为42和64 m V·dec^(-1);在0.5 mol·L^(-1)H2SO4中,过电压为50 m V下,催化剂的质量活性和转换频率值分别为36.5 A·mgPt^(-1)和11.5 s^(-1);在1.0 mol·L^(-1)PBS中,过电压为100 m V下,催化剂质量活性和转换频率分别为4.1 A·mgPt^(-1)和4.2 s^(-1),PtNP/Nb_(2)CT_(x)催化剂表现出优异的HER活性。最后在电流密度为10 m A·cm^(-2)下,0.5 mol·L^(-1)H2SO4和1.0 mol·L^(-1)PBS电解液中通过计时电流法进行5 h的稳定性测试,该催化剂均表现出良好的稳定性。该催化剂的成功合成为制备低Pt含量高性能电催化析氢材料提供了新的思路和研究方法。展开更多
MXenes are well known for their potential application in supercapacitors due to their high-rate intercalation pseudocapacitance and long cyclability.However,the reported low capacity of pristine MXenes hinders their p...MXenes are well known for their potential application in supercapacitors due to their high-rate intercalation pseudocapacitance and long cyclability.However,the reported low capacity of pristine MXenes hinders their practical application in lithium-ion batteries.In this work,a robust strategy is developed to control the functional groups of Nb_2 CT_x MXene.The capacity of pristine Nb_2 CT_x MXene can be significantly increased by Li~+ intercalation and surface modification.The specific capacity of the treated Nb_2 CT_x is up to 448 mAh g^(-1) at 0.05 A g^(-1),and at a large current density of 2 A g^(-1) remains a high reversible capacity retention rate of 75% after an ultra-long cycle of 2000 cycles.These values exceed most of the reported pristine MXenes(including the most studied Ti_3 C_2 T_x) and carbon-based materials.It demonstrates that this strategy has great help to improve the electrochemical performance of pristine MXene,and the results enhance the promise of MXenes in the application of lithium-ion batteries.展开更多
Electrochemical oxygen reduction reaction(ORR)for preparing hydrogen peroxide(H_(2)O_(2))is a promising way to replace the anthraquinone method.The key to H_(2)O_(2)production is the development of catalysts to regula...Electrochemical oxygen reduction reaction(ORR)for preparing hydrogen peroxide(H_(2)O_(2))is a promising way to replace the anthraquinone method.The key to H_(2)O_(2)production is the development of catalysts to regulate the oxygen reduction reaction pathway.Here,nitrogen-doped Nb_(2)CT_(x)was prepared by NH3 annealing method.Compared with precursor Nb_(2)AlC(67.01%)and pure Nb_(2)CT_(x)(75.70%),nitrogen-doped Nb_(2)CT_(x)exhibited excellent performance for 2e−ORR with>90%H_(2)O_(2)selectivity(at 0.4 V vs.reversible hydrogen electrode(RHE)).Faradic efficiency of nitrogen-doped Nb_(2)CT_(x)reached 80.75%,whereas those for Nb2AlC and Nb_(2)CT_(x)were 60.35%and 39.27%,respectively.A desirable catalytic stability for 50 h was observed.Density functional theory(DFT)calculations indicated excellent activity of the nitrogen-doped Nb_(2)CT_(x)was attributed to the introduction of N.This excellent activity was conducive to the adsorption of oxygen and promoted the formation of the OOH intermediate.This work can serve as an important reference for regulating the electronic structure of MXene to expand the application area in the electrochemical field.展开更多
3d-transition metal(Fe,Co,Ni,and Mn)-based MXene materials have been predicted to demonstrate exceptional electrochemical performance because of their good electrical conductivity and the presence of metallic atoms wi...3d-transition metal(Fe,Co,Ni,and Mn)-based MXene materials have been predicted to demonstrate exceptional electrochemical performance because of their good electrical conductivity and the presence of metallic atoms with multiple charge states.However,until now,there have been no reports on MXenes based on Fe,Co,Ni,and Mn,due to the lack of 3d-metal-layered precursors.Herein,we successfully synthesized the first 3d-transition metal-based MXenes,Mn_(2)CT_(x) by exfoliating a layered precursor derived from the anti-perovskite bulk Mn3GaC.The as-prepared Mn_(2)CT_(x) MXene nanosheets were employed as anode materials in lithium-ion batteries,which exhibited stable storage capacity of 764.7 mAh·g^(-1) at 0.5 C,placing its storage capacities at an upper-middle level compared with other reported MXene materials as well as other Mn-based anode materials.Overall,this study opens a new avenue for MXene research by synthesizing 3d-transition metal-based MXenes for electrochemical applications.展开更多
Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene...Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene via a partial oxidation process.Relying on the annealing in the air atmosphere,the controlled oxidation behavior transformed V_(2)CT_(x) MXene partially to V_(2)O_(5) and formed a derivative hybrid of V_(2)O_(5)/V_(2)CT_(x) MXene.As a result,a package of capacity,rate performance,and cyclability can be enhanced.This work explores the derived behavior of MXenes and provides a route for constructing the hybrid with less interface contact.Furthermore,these findings can be extended to other MXene materials.展开更多
With the continuous development of two-dimensional (2D) transition metal carbides and nitrides(collectively referred to as MXene).Nowadays,more than 70 MXene materials have been discovered,and the number is still incr...With the continuous development of two-dimensional (2D) transition metal carbides and nitrides(collectively referred to as MXene).Nowadays,more than 70 MXene materials have been discovered,and the number is still increasing.Among them,the V_(2)CT_(x) MXene has attracted considerable attentions due to its outstanding physical and chemical properties.In this review,we mainly discussed the emerging V_(2)CT_(x) MXene and its derivative systems in various energy storage devices.Firstly,an introduction of the V-based MXene and its derivatives along with their synthetic methodologies is provided,then we summarize their applications in specific energy storage devices,such as metal (Li,Na,K,Mg,Zn and Al) ion batteries,lithium-sulfur batteries,supercapacitors and metal-ion capacitors.Finally,the main challenges and future perspectives existing in V-based MXene and its derivatives are reasonably put forward.展开更多
In this study,a robust macroscale liquid superlubricity with a coefficient of friction of 0.004 was achieved by introducing molybdenum carbide(Mo_(2)CT_(x))MXene nanoparticles as lubricating additives in a lithium hex...In this study,a robust macroscale liquid superlubricity with a coefficient of friction of 0.004 was achieved by introducing molybdenum carbide(Mo_(2)CT_(x))MXene nanoparticles as lubricating additives in a lithium hexafluorophosphate-based ionic liquid at Si_(3)N_(4)-sapphire interfaces.The maximal contact pressure in the superlubricity state could reach 1.42 GPa,which far exceeds the limit of the superlubricity regime in previous studies.The results indicate that a composite tribofilm(mainly containing molybdenum oxide and phosphorus oxide)that formed at the interface by a tribochemical reaction contributed to the excellent antiwear performance.Furthermore,the extremely low shear strength of the tribofilm and the interlayers of Mo_(2)CT_(x)MXene contributed to the superlubricity.This work demonstrates the promising potential of Mo_(2)CT_(x)MXene in improving superlubricity properties,which could accelerate the application of superlubricity in mechanical systems.展开更多
文摘降低催化剂中贵金属Pt含量是构建高性能析氢反应(Hydrogen evolution reaction,HER)电催化剂的关键。通过电化学沉积法将Cu纳米修饰到二维Nb_(2)CT_(x)表面,然后利用电化学置换反应制备得到二维Nb_(2)CT_(x)负载Pt纳米颗粒(PtNP/Nb_(2)CT_(x))催化剂。采用SEM、XRD和XPS等手段对所得催化剂的形貌、结构及组成进行表征,并研究了PtNP/Nb_(2)CT_(x)催化剂在酸性和中性介质中的电催化HER性能。结果表明,在10 m A·cm^(-2)电流密度下,PtNP/Nb_(2)CT_(x)催化剂在0.5 mol·L^(-1)H2SO4和1.0 mol·L^(-1)PBS电解液中的过电压分别为38 m V和146 m V,Tafel斜率分别为42和64 m V·dec^(-1);在0.5 mol·L^(-1)H2SO4中,过电压为50 m V下,催化剂的质量活性和转换频率值分别为36.5 A·mgPt^(-1)和11.5 s^(-1);在1.0 mol·L^(-1)PBS中,过电压为100 m V下,催化剂质量活性和转换频率分别为4.1 A·mgPt^(-1)和4.2 s^(-1),PtNP/Nb_(2)CT_(x)催化剂表现出优异的HER活性。最后在电流密度为10 m A·cm^(-2)下,0.5 mol·L^(-1)H2SO4和1.0 mol·L^(-1)PBS电解液中通过计时电流法进行5 h的稳定性测试,该催化剂均表现出良好的稳定性。该催化剂的成功合成为制备低Pt含量高性能电催化析氢材料提供了新的思路和研究方法。
基金Project supported by the National Science Foundation of China (No.51772070 and 51772069)。
文摘MXenes are well known for their potential application in supercapacitors due to their high-rate intercalation pseudocapacitance and long cyclability.However,the reported low capacity of pristine MXenes hinders their practical application in lithium-ion batteries.In this work,a robust strategy is developed to control the functional groups of Nb_2 CT_x MXene.The capacity of pristine Nb_2 CT_x MXene can be significantly increased by Li~+ intercalation and surface modification.The specific capacity of the treated Nb_2 CT_x is up to 448 mAh g^(-1) at 0.05 A g^(-1),and at a large current density of 2 A g^(-1) remains a high reversible capacity retention rate of 75% after an ultra-long cycle of 2000 cycles.These values exceed most of the reported pristine MXenes(including the most studied Ti_3 C_2 T_x) and carbon-based materials.It demonstrates that this strategy has great help to improve the electrochemical performance of pristine MXene,and the results enhance the promise of MXenes in the application of lithium-ion batteries.
基金the National Key R&D Program of China(No.2021YFA1500900)the National Natural Science Foundation of China(Nos.22141001 and U21A20298).
文摘Electrochemical oxygen reduction reaction(ORR)for preparing hydrogen peroxide(H_(2)O_(2))is a promising way to replace the anthraquinone method.The key to H_(2)O_(2)production is the development of catalysts to regulate the oxygen reduction reaction pathway.Here,nitrogen-doped Nb_(2)CT_(x)was prepared by NH3 annealing method.Compared with precursor Nb_(2)AlC(67.01%)and pure Nb_(2)CT_(x)(75.70%),nitrogen-doped Nb_(2)CT_(x)exhibited excellent performance for 2e−ORR with>90%H_(2)O_(2)selectivity(at 0.4 V vs.reversible hydrogen electrode(RHE)).Faradic efficiency of nitrogen-doped Nb_(2)CT_(x)reached 80.75%,whereas those for Nb2AlC and Nb_(2)CT_(x)were 60.35%and 39.27%,respectively.A desirable catalytic stability for 50 h was observed.Density functional theory(DFT)calculations indicated excellent activity of the nitrogen-doped Nb_(2)CT_(x)was attributed to the introduction of N.This excellent activity was conducive to the adsorption of oxygen and promoted the formation of the OOH intermediate.This work can serve as an important reference for regulating the electronic structure of MXene to expand the application area in the electrochemical field.
基金supported by the funding from the National Natural Science Foundation of China(Nos.52003163,22105129)Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515010670,2022A1515011048)+2 种基金Science and Technology Innovation Commission of Shenzhen(No.20200812112006001)and Shenzhen University-Taipei University of Science and Technology Collaboration Project(Nos.2022005,2022015).X.Cai appreciates the help from the electron microscopy center at Shenzhen University for providing the aberration-corrected HAADF STEM testing services.H.Sun acknowledges the support from the Guangdong Special Support Program(No.2021TQ06C953)the Science and Technology Planning Projects of Shenzhen Municipality(Nos.JCYJ20190806142614541,GXWD20220811164433002).
文摘3d-transition metal(Fe,Co,Ni,and Mn)-based MXene materials have been predicted to demonstrate exceptional electrochemical performance because of their good electrical conductivity and the presence of metallic atoms with multiple charge states.However,until now,there have been no reports on MXenes based on Fe,Co,Ni,and Mn,due to the lack of 3d-metal-layered precursors.Herein,we successfully synthesized the first 3d-transition metal-based MXenes,Mn_(2)CT_(x) by exfoliating a layered precursor derived from the anti-perovskite bulk Mn3GaC.The as-prepared Mn_(2)CT_(x) MXene nanosheets were employed as anode materials in lithium-ion batteries,which exhibited stable storage capacity of 764.7 mAh·g^(-1) at 0.5 C,placing its storage capacities at an upper-middle level compared with other reported MXene materials as well as other Mn-based anode materials.Overall,this study opens a new avenue for MXene research by synthesizing 3d-transition metal-based MXenes for electrochemical applications.
基金support provided by the National Natural Science Foundation of China (grant No.51932005)Liao Ning Revitalization Talents Program (grant No.XLYC1807175)the Research Fund of SYNL,the Science and Technology Research Project of Education Department of jilin Province (grant Nos.JKH20210453KJ,JKH20210449KJ).
文摘Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene via a partial oxidation process.Relying on the annealing in the air atmosphere,the controlled oxidation behavior transformed V_(2)CT_(x) MXene partially to V_(2)O_(5) and formed a derivative hybrid of V_(2)O_(5)/V_(2)CT_(x) MXene.As a result,a package of capacity,rate performance,and cyclability can be enhanced.This work explores the derived behavior of MXenes and provides a route for constructing the hybrid with less interface contact.Furthermore,these findings can be extended to other MXene materials.
基金financially supported by the National Natural Science Foundation of China (Nos. 51772127, 51772131 and 52072151)Taishan Scholars (No. ts201712050)+2 种基金Jinan Independent Innovative Teamthe Natural Science Doctoral Foundation of Shandong Province (No. ZR2019BEM038)the Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong。
文摘With the continuous development of two-dimensional (2D) transition metal carbides and nitrides(collectively referred to as MXene).Nowadays,more than 70 MXene materials have been discovered,and the number is still increasing.Among them,the V_(2)CT_(x) MXene has attracted considerable attentions due to its outstanding physical and chemical properties.In this review,we mainly discussed the emerging V_(2)CT_(x) MXene and its derivative systems in various energy storage devices.Firstly,an introduction of the V-based MXene and its derivatives along with their synthetic methodologies is provided,then we summarize their applications in specific energy storage devices,such as metal (Li,Na,K,Mg,Zn and Al) ion batteries,lithium-sulfur batteries,supercapacitors and metal-ion capacitors.Finally,the main challenges and future perspectives existing in V-based MXene and its derivatives are reasonably put forward.
基金This work was financially supported by the National Key R&D Program of China(No.2020YFA0711003)the National Natural Science Foundation of China(Nos.52005290,51775295,and 52175174)the Open Research Fund of Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments(No.KF202004).
文摘In this study,a robust macroscale liquid superlubricity with a coefficient of friction of 0.004 was achieved by introducing molybdenum carbide(Mo_(2)CT_(x))MXene nanoparticles as lubricating additives in a lithium hexafluorophosphate-based ionic liquid at Si_(3)N_(4)-sapphire interfaces.The maximal contact pressure in the superlubricity state could reach 1.42 GPa,which far exceeds the limit of the superlubricity regime in previous studies.The results indicate that a composite tribofilm(mainly containing molybdenum oxide and phosphorus oxide)that formed at the interface by a tribochemical reaction contributed to the excellent antiwear performance.Furthermore,the extremely low shear strength of the tribofilm and the interlayers of Mo_(2)CT_(x)MXene contributed to the superlubricity.This work demonstrates the promising potential of Mo_(2)CT_(x)MXene in improving superlubricity properties,which could accelerate the application of superlubricity in mechanical systems.
