Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/...Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/TaO_(x) structure,which is facilitated by a wedge-shaped HfO_(2)buffer layer.The field-free switching ratio varies with HfO_(2)thickness,reaching optimal performance at 25 nm.This phenomenon is attributed to the lateral anisotropy gradient of the Co layer,which is induced by the wedge-shaped HfO_(2)buffer layer.The thickness gradient of HfO_(2)along the wedge creates a corresponding lateral anisotropy gradient in the Co layer,correlating with the switching ratio.These findings indicate that field-free SOT switching can be achieved through designing buffer layer,offering a novel approach to innovating spin-orbit device.展开更多
氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过...氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。展开更多
The construction of oxide/metal composite catalysts is a competent means of exploiting the electronic interactions between oxide/metal to enhance catalytic activity.In this work,we construct a novel heterogeneous comp...The construction of oxide/metal composite catalysts is a competent means of exploiting the electronic interactions between oxide/metal to enhance catalytic activity.In this work,we construct a novel heterogeneous composite(Ru/HfO_(2)-NC)with Ru/HfO2nanoparticles nested in nitrogen-doped porous carbon via a zeolitic imidazole frameworks-assisted(ZIF)co-precipitation and calcination approach.In particular,ZIF guides an in-situ construction of nested configuration and confines the scattered nanoparticles.Strikingly,Ru/HfO_(2)-NC exhibits unusual ORR activity,superb durability,and methanol tolerance in0.1 M KOH solution with high half-wave potential(E1/2)of 0.83 V and follows a near-4e-reaction pathway.Additionally,the ZAB assembled with cathodic Ru/HfO_(2)-NC outputs a power density of 157.3 m W cm^(-2),a specific capacity of 775 mA h g-1Zn,and a prolonged lifespan of 258 h at 5 mA cm^(-2).Meanwhile,the catalyst has demonstrated potential applicability in flexible ZAB.As suggested by experimental results and density functional theory(DFT)analysis,the remarkable property possibly originated from the optimization of the adsorption and desorption of reactive intermediates caused by the reconfiguration of the electronic structure between Ru and HfO_(2).展开更多
The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attentio...The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attention has been focused on modulating and developing catalyst interface contact engineering between a carbon substrate and dispersed metal.Here,a highly dispersed ultrafine ruthenium(Ru)NP strategy by double spatial confinement is proposed,that is,incorporating directed growth of metal–organic framework crystals into a bacterial cellulose templating substrate to integrate their respective merits as an excellent electrocatalytic cathode catalyst for a quasi-solid-state Li–O_(2) battery.The porous carbon matrix with highly dispersed ultrafine Ru NPs is well designed and used as cathode catalysts in a Li–O_(2) battery,demonstrating a high discharge areal capacity of 6.82 mAh cm^(–2) at 0.02 mA cm^(–2),a high-rate capability of 4.93 mAh cm^(–2) at 0.2 mA cm^(–2),and stable discharge/charge cycling for up to 500 cycles(2000 h)with low overpotentials of~1.4 V.This fundamental understanding of the structure–performance relationship demonstrates a new and promising approach to optimize highly efficient cathode catalysts for solid-state Li–O_(2) batteries.展开更多
The defect-free structure of Mo-based materials is a“double-edged sword”,which endows the material with excellent stability,but limits its chemical versatility and application in electrochemical hydrogen evolution r...The defect-free structure of Mo-based materials is a“double-edged sword”,which endows the material with excellent stability,but limits its chemical versatility and application in electrochemical hydrogen evolution reaction(HER).Carbon doping engineering is an attractive strategy to effectively improve the performance of Mo-based catalyst and maintain their stability.Herein,we report a cross-linked porous carbon-doped MoO_(2)(C–MoO_(2))-based catalyst Ru/C–MoO_(2) for electrochemical HER,which is prepared by the convenient redox solid-phase reaction(SPR)of porous RuO_(2)/Mo_(2)C composite precursor.Theoretical studies reveal that due to the presence of carbon atoms,the electronic structure of C–MoO_(2) has been properly adjusted,and the loaded small Ru nanoparticles provide a fast water dissociation rate and moderate H adsorption strength.In electrochemical studies under a pH-universal environment,Ru/C–MoO_(2) electrocatalyst exhibits a low overpotential at a current density of 10 mA cm^(-2) and has a low Tafel slope.Meanwhile,Ru/C-MoO_(2) has excellent stability for more than 100 h at an initial current density of 100 mA cm^(-2).展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.12274108)the Natural Science Foundation of Zhejiang Province,China (Grant Nos.LY23A040008 and LY23A040008)the Basic Scientific Research Project of Wenzhou,China (Grant No.G20220025)。
文摘Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/TaO_(x) structure,which is facilitated by a wedge-shaped HfO_(2)buffer layer.The field-free switching ratio varies with HfO_(2)thickness,reaching optimal performance at 25 nm.This phenomenon is attributed to the lateral anisotropy gradient of the Co layer,which is induced by the wedge-shaped HfO_(2)buffer layer.The thickness gradient of HfO_(2)along the wedge creates a corresponding lateral anisotropy gradient in the Co layer,correlating with the switching ratio.These findings indicate that field-free SOT switching can be achieved through designing buffer layer,offering a novel approach to innovating spin-orbit device.
文摘氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。
基金supported by the National Natural Science Foundation of China(21965005)the Natural Science Foundation of Guangxi Province(2021GXNSFAA076001)+1 种基金the Project of HighLevel Talents of Guangxi(F-KA18015)Guangxi Technology Base and Talent Subject(GUIKE AD18126001,GUIKE AD20297039)。
文摘The construction of oxide/metal composite catalysts is a competent means of exploiting the electronic interactions between oxide/metal to enhance catalytic activity.In this work,we construct a novel heterogeneous composite(Ru/HfO_(2)-NC)with Ru/HfO2nanoparticles nested in nitrogen-doped porous carbon via a zeolitic imidazole frameworks-assisted(ZIF)co-precipitation and calcination approach.In particular,ZIF guides an in-situ construction of nested configuration and confines the scattered nanoparticles.Strikingly,Ru/HfO_(2)-NC exhibits unusual ORR activity,superb durability,and methanol tolerance in0.1 M KOH solution with high half-wave potential(E1/2)of 0.83 V and follows a near-4e-reaction pathway.Additionally,the ZAB assembled with cathodic Ru/HfO_(2)-NC outputs a power density of 157.3 m W cm^(-2),a specific capacity of 775 mA h g-1Zn,and a prolonged lifespan of 258 h at 5 mA cm^(-2).Meanwhile,the catalyst has demonstrated potential applicability in flexible ZAB.As suggested by experimental results and density functional theory(DFT)analysis,the remarkable property possibly originated from the optimization of the adsorption and desorption of reactive intermediates caused by the reconfiguration of the electronic structure between Ru and HfO_(2).
基金National Natural Science Foundation of China,Grant/Award Number:22179005National Key Research and Development Program of China,Grant/Award Number:2018YFC1900102。
文摘The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attention has been focused on modulating and developing catalyst interface contact engineering between a carbon substrate and dispersed metal.Here,a highly dispersed ultrafine ruthenium(Ru)NP strategy by double spatial confinement is proposed,that is,incorporating directed growth of metal–organic framework crystals into a bacterial cellulose templating substrate to integrate their respective merits as an excellent electrocatalytic cathode catalyst for a quasi-solid-state Li–O_(2) battery.The porous carbon matrix with highly dispersed ultrafine Ru NPs is well designed and used as cathode catalysts in a Li–O_(2) battery,demonstrating a high discharge areal capacity of 6.82 mAh cm^(–2) at 0.02 mA cm^(–2),a high-rate capability of 4.93 mAh cm^(–2) at 0.2 mA cm^(–2),and stable discharge/charge cycling for up to 500 cycles(2000 h)with low overpotentials of~1.4 V.This fundamental understanding of the structure–performance relationship demonstrates a new and promising approach to optimize highly efficient cathode catalysts for solid-state Li–O_(2) batteries.
基金This work was financially supported by the National Natural Science Foundation of China (52122308,21905253,51973200)the Natural Science Foundation of Henan (202300410372).
文摘The defect-free structure of Mo-based materials is a“double-edged sword”,which endows the material with excellent stability,but limits its chemical versatility and application in electrochemical hydrogen evolution reaction(HER).Carbon doping engineering is an attractive strategy to effectively improve the performance of Mo-based catalyst and maintain their stability.Herein,we report a cross-linked porous carbon-doped MoO_(2)(C–MoO_(2))-based catalyst Ru/C–MoO_(2) for electrochemical HER,which is prepared by the convenient redox solid-phase reaction(SPR)of porous RuO_(2)/Mo_(2)C composite precursor.Theoretical studies reveal that due to the presence of carbon atoms,the electronic structure of C–MoO_(2) has been properly adjusted,and the loaded small Ru nanoparticles provide a fast water dissociation rate and moderate H adsorption strength.In electrochemical studies under a pH-universal environment,Ru/C–MoO_(2) electrocatalyst exhibits a low overpotential at a current density of 10 mA cm^(-2) and has a low Tafel slope.Meanwhile,Ru/C-MoO_(2) has excellent stability for more than 100 h at an initial current density of 100 mA cm^(-2).
基金financially supported by the National Key R&D Program of China(No.2021YFB2012100)the National Natural Science Foundation of China(Nos.U19A2087,52172134)+1 种基金the Construction of Innovative Provinces in Hunan Province,China(No.2020GK2062)the State Key Laboratory of Powder Metallurgy,Central South University,China。
