The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also p...The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also posing challenges.In this study,an efficient electrocatalyst is successfully constructed through electrodeposition methods,which consists of monodispersed Pt loaded on amorphous/crystalline nickel–iron layered double hydroxide(Pt-SAs/ac-NiFe LDH).The Pt-SAs/ac-NiFe LDH demonstrates an elevated mass activity of 17.66 A mg_(Pt)^(−1)and a significant turnover frequency of 17.90 s^(−1)for HER in alkaline conditions under the overpotential of 100 mV.Meanwhile,for alkaline freshwater and seawater,Pt-SAs/ac-NiFe LDH exhibits ultra-low overpotentials of 141 and 138 mV to reach 1000 mA cm^(−2),respectively.Remarkably,it maintains stable operation for 100 h at 500 mA cm^(−2),showcasing its robustness and reliability.In situ Raman spectra reveal that Pt single atoms(Pt-SAs)accelerate interfacial water dissociation,thereby enhancing the HER kinetics in Pt-SAs/ac-NiFe LDH.Furthermore,theoretical calculation results show significant electronic interaction between the Pt-SAs and the ac-NiFe LDH support.The interaction significantly enhances water adsorption and dissociation,and balances the adsorption/desorption of hydrogen intermediates,ultimately improving HER performance.This research provides a viable method for designing efficient HER catalysts for water electrolysis in alkaline freshwater and seawater under industrial current densities.展开更多
Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are atte...Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are attempted to couple with RuO_(2)for constructing an appropriate Ru—O—M interface.This work aims to construct Co_(3)O_(4)-RuO_(2)heterostructures on carbon sheets(Co_(3)O_(4)/RuO_(2)/NCNS)for boosting electronic transfer and regulation.Experiments and theoretical calculations identify the electronic transfer from Co_(3)O_(4)to RuO_(2)that modulates the electronic structure of metal surfaces/interfaces.Specifically,it leads to the increase in Co3+content,electron-rich state at RuO_(2)surface and electronic accumulation at interfaces.Moreover,this electronic-state modulation optimizes the d-band center in Co_(3)O_(4)/RuO_(2)that lowers the reaction barriers and endows interfaces as the biggest contributor to oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)performance,The Co_(3)O_(4)/RuO_(2)/NCNS shows a quite low potential difference of 0.62 V and remarkable durability for ORR/OER.Co_(3)O_(4)/RuO_(2)/NCNS-assembled ZABs exhibit an excellent specific capacity of 818.3 mA h g^(-1)and a superior lifespan over 750 h.展开更多
Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au...Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration treatment.The well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 frameworks.This novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution reaction.The electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by Au.Meanwhile,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest value.Consequently,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery performance.The work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts.展开更多
Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the develop...Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the development of electrochemicallydriven technologies for efficient hydrogen production and avoid CO_(2) emission. Herein, the hetero-nanocrystals between monodispersed Pt(~ 2 nm) and Ni_(3)S_(2)(~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H_(2) generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni_(3)S_(2) could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH_(3)OH to formate is accomplished at very low potentials(1.45 V) to attain 100 m A cm^(-2) with high electronic utilization rate(~ 98%) and without CO_(2) emission. Meanwhile, the Pt–Ni_(3)S_(2) can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction(HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction(MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 m A cm^(-2) with good reusability.展开更多
Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxy...Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this work,we synthesized a self-supporting heterogeneous NiSe@Co_(0.85)Se/NF electrocatalyst using a facile in situ selenization of transition metal precursors that coated on the nickel foam(NF)in polyol solution.The NF was used as both conductive substrate and nickel source,ensuring superior electronic conductivity for catalyzing.The NiSe@-Co_(0.85)Se/NF exhibited remarkable bifunctional electrocatalytic activities with HER overpotential of 168 mV and OER overpotential of 258 mV to achieve 10 mA·cm-2.The water splitting system using NiSe@Co_(0.85)Se/NF as both anode and cathode electrodes achieved a current density of 10 mA·cm^(-2) at 1.61 V with nearly 100% faradaic efficiency and impressively long-term stability.The efficient bifunctional catalytic performance of NiSe@-Co_(0.85)Se/NF should be attributed to the electronic modulation and synergistic effect between NiSe and Co_(0.85)Se,the intrinsic metallic conductivity and the enlarged active sites exposure.This work provides a facile method for developing heterogeneous bifunctional catalysts for advanced electrochemical energy conversion technologies.展开更多
Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficienc...Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.展开更多
Controlling the local electronic structure of active ingredients to improve the adsorption desorption characteristics of oxygen-containing intermediates over the electrochemical liquid-solid interfaces is a critical c...Controlling the local electronic structure of active ingredients to improve the adsorption desorption characteristics of oxygen-containing intermediates over the electrochemical liquid-solid interfaces is a critical challenge in the field of oxygen reduction reaction(ORR)catalysis.Here,we offer a simple approach for modulating the electronic states of metal nanocrystals by bimetal co-doping into carbon-nitrogen substrate,allowing us to modulate the electronic structure of catalytic active centers.To test our strategy,we designed a typical bimetallic nanoparticle catalyst(Fe-Co NP/NC)to flexibly alter the reaction kinetics of ORR.Our results from synchrotron Xray absorption spectroscopy and X-ray photoelectron spectroscopy showed that the co-doping of iron and cobalt could optimize the intrinsic charge distribution of Fe-Co NP/NC catalyst,promoting the oxygen reduction kinetics and ultimately achieving remarkable ORR activity.Consequently,the carefully designed Fe-Co NP/NC exhibits an ultra-high kinetic current density at the operating voltage(71.94 mA/cm^(2)at 0.80 V),and the half-wave potential achieves 0.915 V,which is obviously better than that of the corresponding controls including Fe NP/NC,Co NP/NC.Our findings provide a unique perspective for optimizing the electronic structure of active centers to achieve higher ORR catalytic activity and faster kinetics.展开更多
Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction ...Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its role.To clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER process.Theoretical calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic species.The modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term durability.This study provides a novel perspective for understanding the role of Fe in the OER process.展开更多
Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performin...Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performing a detailed event study in terms of particle distribution maps and wave–particle variable correlation maps, we report that ULF waves observed by the Mars Atmosphere and Volatile EvolutioN(MAVEN) spacecraft in the Martian foreshock can effectively modulate the suprathermal electron fluxes by the magnetic field fluctuations. In particular, the variations in electron fluxes at energies of ~10–100 eV are significant in the perpendicular direction, showing good relationships with changes in the wave field strength characterized by a correlation coefficient ~0.8. These findings demonstrate the generality of interactions of ULF waves with electrons, even at these low energies, highlighting the importance of such processes throughout the heliosphere.展开更多
Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four plan...Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.展开更多
Rationally designed oxygen evolution reaction(OER)catalysts with structural and compositional superiorities are essential for energy-related electrocatalytic techniques.Transition-metal phosphides have been used as pr...Rationally designed oxygen evolution reaction(OER)catalysts with structural and compositional superiorities are essential for energy-related electrocatalytic techniques.Transition-metal phosphides have been used as promising electrocatalysts for OER.Incorporating heteroatoms into the lattice can induce lattice distortion and redistribution of electron density,consequently modifying the electronic structure and improving catalytic performance.Herein,Fe-and S-substituted Ni_(2)P uniformly dispersed throughout porous carbon substrate(Ni-Fe-P-S@C)was rationally designed through transformation from the pre-synthesized NiFe-metal organic frameworks(NiFe-MOFs)by partial sulfurization and subsequent phosphorization process.Experimental results and density functional theory calculations showed that Fe and S incorporation could modulate the electronic structure of Ni_(2)P and alter the adsorption free energies of reaction intermediates,contributing to admirable electrocatalytic activity and stability toward OER.Notably,the in-situ formed partially oxidized surface was vital to further improve the local environment.This proposed cation-and anion-substitution strategy will bring new inspiration to boost the electrocatalytic performance of transition-metal-based electrocatalysts for energy conversion applications.展开更多
Large-scale electrolysis of water to produce high-purity hydrogen is one of the effective ways to solve the energy crisis and environmental pollution problems.However,efficient,cheap and stable catalysts are one of th...Large-scale electrolysis of water to produce high-purity hydrogen is one of the effective ways to solve the energy crisis and environmental pollution problems.However,efficient,cheap and stable catalysts are one of the bottlenecks for industrial application in water splitting.Herein,a facile one-step hydrothermal process was applied to fabricate Mn-doped nickel ferrite nanosheets(Mn-NiFe_(2)O_(4))which shown a low overpotential of 200 mV at 50 mA·cm^(-2)and a small Tafel slope of 47 mV·dec^(-1),together with a prominent turnover frequency(TOF)value(0.14 s^(-1))and robust stability.The in-situ UV-vis spectroscopy unveiled the surface reconstruction to generate NiOOH as active sites during oxygen evolution reaction(OER).The excellent electrocatalytic activity of Mn-NiFe_(2)O_(4)is attributed to the vertically grown nanosheets for exposure more active sites,rich oxygen vacancies,and the hybridization between Ni 3d and O 2p orbitals caused by Mn doping.This work should provide a facile strategy by Mn-doping to simultaneously engineer oxygen vacancies and electronic structure for synergistically triggering oxygen evolution reaction.展开更多
Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanopart...Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.展开更多
Developing an efficientmethod to improve the photocatalytic efficiency of graphitic carbon nitride(g-C3 N4)is of great significance for solar H2 production.Electronic structure modulation has been considered one of th...Developing an efficientmethod to improve the photocatalytic efficiency of graphitic carbon nitride(g-C3 N4)is of great significance for solar H2 production.Electronic structure modulation has been considered one of the most crucial strategies to improving the photocatalytic efficiency of g-C_(3)N_(4),but how to efficiently modulate its electronic structure remains a huge challenge.Herein,we,for the first time,report a facile and highly-efficient approach to modulating the electronic structure of g-C_(3)N_(4)through single Ag atom implantation with a Ag_(1)-N_(3)coordination configuration into the g-C_(3)N_(4)framework.展开更多
Regulation the electronic density of solid-state electrolyte by donor–acceptor(D–A)system can achieve highly-selective Li^(+)transportation and conduction in solid-state Li metal batteries.This study reports a high-...Regulation the electronic density of solid-state electrolyte by donor–acceptor(D–A)system can achieve highly-selective Li^(+)transportation and conduction in solid-state Li metal batteries.This study reports a high-performance solid-state electrolyte thorough D–A-linked covalent organic frameworks(COFs)based on intramolecular charge transfer interactions.Unlike other reported COFbased solid-state electrolyte,the developed concept with D–A-linked COFs not only achieves electronic modulation to promote highly-selective Li^(+)migration and inhibit Li dendrite,but also offers a crucial opportunity to understand the role of electronic density in solid-state Li metal batteries.The introduced strong electronegativity F-based ligand in COF electrolyte results in highlyselective Li^(+)(transference number 0.83),high ionic conductivity(6.7×10^(-4)S cm^(−1)),excellent cyclic ability(1000 h)in Li metal symmetric cell and high-capacity retention in Li/LiFePO_(4)cell(90.8%for 300 cycles at 5C)than substituted C-and N-based ligands.This is ascribed to outstanding D–A interaction between donor porphyrin and acceptor F atoms,which effectively expedites electron transferring from porphyrin to F-based ligand and enhances Li^(+)kinetics.Consequently,we anticipate that this work creates insight into the strategy for accelerating Li^(+)conduction in high-performance solid-state Li metal batteries through D–A system.展开更多
Solving the problem of aggregation and nonuniform dispersion of platinum(Pt)nanoparticles(NPs)is the key to obtaining high catalytic activity.Graphene aerogels(GAs)with large accessible specific surface area and abund...Solving the problem of aggregation and nonuniform dispersion of platinum(Pt)nanoparticles(NPs)is the key to obtaining high catalytic activity.Graphene aerogels(GAs)with large accessible specific surface area and abundant surface defects are considered to be excellent substrate materials for reducing Pt agglomeration and enhancing catalytic activity.Herein,Pt-based GA composites(Pt-GA-x)featuring homogeneous particle dispersion and high activity were successfully synthesized through a one-step reduction method.Fourier transform infrared(FTIR),Raman,and X-ray photoelectron spectroscopy(XPS)test results indicate that the presence of a large number of oxygen-containing functionalities in GA for anchoring Pt NPs,and the interaction with GA produces electronically structured Pt and defect-rich GA substrates.The obtained electrocatalyst Pt-GA-2 possesses a large specific surface area(443.46 m^(2)·g^(−1)),low Pt loading(3.08 wt%),and uniformly dispersed Pt NPs(average 42 nm).As an advanced hydrogen evolution reaction(HER)electrocatalyst,an overpotential of 34 mV is achieved at a current density of 10 mA·cm^(−2)in 0.5 M H_(2)SO_(4)electrolyte,together with a low Tafel slope of 33.2 mV·dec^(−1).Hence,high mass activity(5623 mA·mgPt^(−1))and turnover frequency(TOF=2.57 s^(−1)at η=100 mV)can be obtained,which are 6.81 and 6.76 times higher than those of commercial Pt/C catalysts.All these are attributed to enormous surface defects over GA and electron enrichment on Pt NPs.The present study highlights the unique advantages of GA in electrochemical energy conversion and provides new avenues to fabricate advanced HER electrocatalysts.展开更多
Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high co...Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.展开更多
High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-...High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-IPEM）, consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management.展开更多
The biggest challenge is to develop a low cost and readily available catalyst to replace expensive commercial Pt/C for efficient electrochemical oxygen reduction reaction(ORR).In this research,closo-[B_(12)H_(12)]^(2−...The biggest challenge is to develop a low cost and readily available catalyst to replace expensive commercial Pt/C for efficient electrochemical oxygen reduction reaction(ORR).In this research,closo-[B_(12)H_(12)]^(2−)and 1,10-phenanthroline-iron complexes were introduced into the porous metal-organic framework by impregnation method,and further annealing treatment achieved the successful anchoring of single-atom-Fe in B-doped CN Matrix(FeN4CB).The ORR activity of FeN4CB is comparable to the widely used commercial 20 wt%Pt/C.Where the half-wave potential(E_(1/2))in alkaline medium up to 0.84 V,and even in the face of challenging ORR in acidic medium,the E_(1/2)of ORR driven by FeN4CB is still as high as 0.81 V.When FeN4CB was used as air cathode,the open circuit voltage of Zn-air battery reaches 1.435 V,and the power density and specific capacity are as high as 177 mW cm^(−2)and 800 mAh g_(Zn)^(−1)(theoretical value:820 mAh g_(Zn)^(−1)),respectively.The dazzling point of FeN4CB also appears in the high ORR stability,whether in alkaline or acidic media,E_(1/2)and limiting current density are still close to the initial value after 5000 times cycles.After continuously running the charge-discharge test for 220 h,the charge voltage and discharge voltage of the rechargeable zinc-air battery with FeN4CB as the air cathode maintained the initial state.Density functional theory calculations reveals that introducing B atom to Fe–N4–C can adjust the electronic structure to easily break O=O bond and significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.展开更多
Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(...Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(AHE),yet remains a major challenge.Herein,we report that by substituting a W atom of WS_(2) with a series of transition metal atoms,sulfur vacancy-confined Cu in the WS_(2) basal plane(Cu@WS_(2)-Sv)is theoretically screened as a superior non-noble metal-based catalyst with higher activity,selectivity,and stability for the AHE than other candidates.The co-adsorption of C_(2)H_(2) and H_(2) and hydrogenation of C_(2)H_(3)^(*) to C_(2)H_(4)^(*) are revealed as the key steps establishing a volcano-like activity trend among the candidates,which present Cu@WS_(2)-Sv as the optimum catalyst combined with molecular dynamics and reaction kinetics analyses.The kinetically more favorable desorption of C_(2)H_(4) than the over hydrogenation path validates a higher selectivity toward C_(2)H_(4) over C_(2)H_(6).Furthermore,a machine-learning model reveals the significant effect of d-electron number and electronegativity of the metal heteroatoms in modulating the AHE activity.展开更多
基金funded by the National Key Research and Development Program of China(2022YFB3803600)the National Natural Science Foundation of China(22368050,22378346)+4 种基金the Key Research and Development Program of Yunnan Province(202302AF080002)Yunnan Basic Applied Research Project(202401AT070460,202401AU070229)Xingdian Talent Support Program Project in Yunnan Province,the Scientific Research Fund Project of Yunnan Education Department(2024J0014,2024J0013)the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050259,YPML-2023050260,YPML-20240502008)the Scientific Research and Innovation Project of Postgraduate Students in the Academic Degree of Yunnan University.
文摘The reasonable development and design of high-efficiency and low-cost electrocatalysts for hydrogen evolution reaction(HER)under industrial current densities are imperative for achieving carbon neutrality,while also posing challenges.In this study,an efficient electrocatalyst is successfully constructed through electrodeposition methods,which consists of monodispersed Pt loaded on amorphous/crystalline nickel–iron layered double hydroxide(Pt-SAs/ac-NiFe LDH).The Pt-SAs/ac-NiFe LDH demonstrates an elevated mass activity of 17.66 A mg_(Pt)^(−1)and a significant turnover frequency of 17.90 s^(−1)for HER in alkaline conditions under the overpotential of 100 mV.Meanwhile,for alkaline freshwater and seawater,Pt-SAs/ac-NiFe LDH exhibits ultra-low overpotentials of 141 and 138 mV to reach 1000 mA cm^(−2),respectively.Remarkably,it maintains stable operation for 100 h at 500 mA cm^(−2),showcasing its robustness and reliability.In situ Raman spectra reveal that Pt single atoms(Pt-SAs)accelerate interfacial water dissociation,thereby enhancing the HER kinetics in Pt-SAs/ac-NiFe LDH.Furthermore,theoretical calculation results show significant electronic interaction between the Pt-SAs and the ac-NiFe LDH support.The interaction significantly enhances water adsorption and dissociation,and balances the adsorption/desorption of hydrogen intermediates,ultimately improving HER performance.This research provides a viable method for designing efficient HER catalysts for water electrolysis in alkaline freshwater and seawater under industrial current densities.
基金supported by the National Natural Science Foundation of China(52273264)the Outstanding Youth Fund of Heilongjiang Province(JQ 2020B002).
文摘Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are attempted to couple with RuO_(2)for constructing an appropriate Ru—O—M interface.This work aims to construct Co_(3)O_(4)-RuO_(2)heterostructures on carbon sheets(Co_(3)O_(4)/RuO_(2)/NCNS)for boosting electronic transfer and regulation.Experiments and theoretical calculations identify the electronic transfer from Co_(3)O_(4)to RuO_(2)that modulates the electronic structure of metal surfaces/interfaces.Specifically,it leads to the increase in Co3+content,electron-rich state at RuO_(2)surface and electronic accumulation at interfaces.Moreover,this electronic-state modulation optimizes the d-band center in Co_(3)O_(4)/RuO_(2)that lowers the reaction barriers and endows interfaces as the biggest contributor to oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)performance,The Co_(3)O_(4)/RuO_(2)/NCNS shows a quite low potential difference of 0.62 V and remarkable durability for ORR/OER.Co_(3)O_(4)/RuO_(2)/NCNS-assembled ZABs exhibit an excellent specific capacity of 818.3 mA h g^(-1)and a superior lifespan over 750 h.
基金National Natural Science Foundation of China,Grant/Award Numbers:52102260,52171211,51972220,61903235,U22A20145Shandong Provincial Natural Science Foundation,Grant/Award Numbers:ZR2020QB069,ZR2022ME051+4 种基金National Key Research and Development Program of China,Grant/Award Number:2022YFB4002004Scientific and Technological Innovation Ability Improvement Project of Minor Enterprises in Shandong Province,Grant/Award Number:2022TSGC1021Announce the List and Take Charge Project in Jinan,Grant/Award Number:202214012Major innovation project for integrating science,education and industry of Qilu University of Technology (Shandong Academy of Sciences),Grant/Award Numbers:2022JBZ01-07,2022PY044China Postdoctoral Science Foundation,Grant/Award Number:2022M711545。
文摘Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration treatment.The well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 frameworks.This novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution reaction.The electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by Au.Meanwhile,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest value.Consequently,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery performance.The work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts.
基金the financial support of Guangdong Basic and Applied Basic Research Foundation (No. 2023A1515010940)Shenzhen Natural Science Fund (the Stable Support Plan Program No. 20220809160022001)the Shenzhen Science and Technology Programs (No. ZDSYS20220527171401003, KQTD20190929173914967)。
文摘Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the development of electrochemicallydriven technologies for efficient hydrogen production and avoid CO_(2) emission. Herein, the hetero-nanocrystals between monodispersed Pt(~ 2 nm) and Ni_(3)S_(2)(~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H_(2) generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni_(3)S_(2) could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH_(3)OH to formate is accomplished at very low potentials(1.45 V) to attain 100 m A cm^(-2) with high electronic utilization rate(~ 98%) and without CO_(2) emission. Meanwhile, the Pt–Ni_(3)S_(2) can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction(HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction(MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 m A cm^(-2) with good reusability.
基金financially supported by the National Natural Science Foundation of China(No.51804216)。
文摘Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this work,we synthesized a self-supporting heterogeneous NiSe@Co_(0.85)Se/NF electrocatalyst using a facile in situ selenization of transition metal precursors that coated on the nickel foam(NF)in polyol solution.The NF was used as both conductive substrate and nickel source,ensuring superior electronic conductivity for catalyzing.The NiSe@-Co_(0.85)Se/NF exhibited remarkable bifunctional electrocatalytic activities with HER overpotential of 168 mV and OER overpotential of 258 mV to achieve 10 mA·cm-2.The water splitting system using NiSe@Co_(0.85)Se/NF as both anode and cathode electrodes achieved a current density of 10 mA·cm^(-2) at 1.61 V with nearly 100% faradaic efficiency and impressively long-term stability.The efficient bifunctional catalytic performance of NiSe@-Co_(0.85)Se/NF should be attributed to the electronic modulation and synergistic effect between NiSe and Co_(0.85)Se,the intrinsic metallic conductivity and the enlarged active sites exposure.This work provides a facile method for developing heterogeneous bifunctional catalysts for advanced electrochemical energy conversion technologies.
基金This study was financially supported by the National Natural Science Foundation of China(51973079,51773075 and 21875084)the Project of Department of Scienceand Technology of Jilin Province,China(20190101013JH).
文摘Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.
基金supported by the Natural Science Foundation of Anhui Province(No.2208085J01 and No.2208085QA28).
文摘Controlling the local electronic structure of active ingredients to improve the adsorption desorption characteristics of oxygen-containing intermediates over the electrochemical liquid-solid interfaces is a critical challenge in the field of oxygen reduction reaction(ORR)catalysis.Here,we offer a simple approach for modulating the electronic states of metal nanocrystals by bimetal co-doping into carbon-nitrogen substrate,allowing us to modulate the electronic structure of catalytic active centers.To test our strategy,we designed a typical bimetallic nanoparticle catalyst(Fe-Co NP/NC)to flexibly alter the reaction kinetics of ORR.Our results from synchrotron Xray absorption spectroscopy and X-ray photoelectron spectroscopy showed that the co-doping of iron and cobalt could optimize the intrinsic charge distribution of Fe-Co NP/NC catalyst,promoting the oxygen reduction kinetics and ultimately achieving remarkable ORR activity.Consequently,the carefully designed Fe-Co NP/NC exhibits an ultra-high kinetic current density at the operating voltage(71.94 mA/cm^(2)at 0.80 V),and the half-wave potential achieves 0.915 V,which is obviously better than that of the corresponding controls including Fe NP/NC,Co NP/NC.Our findings provide a unique perspective for optimizing the electronic structure of active centers to achieve higher ORR catalytic activity and faster kinetics.
基金financially supported by the Scientific and Technological Development Program of Jilin Province(20220201138GX)the support of the National Key R&D Program of China(No.2022YFA1503801)+1 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-022)the Young Cross Team Project of CAS(No.JCTD-2021-14)。
文摘Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its role.To clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER process.Theoretical calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic species.The modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term durability.This study provides a novel perspective for understanding the role of Fe in the OER process.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42188101, 42174188, 42474217, 42330207, 42374193, 42241143, and 42025404)the National Key R&D Program of China (Grant Nos. 2022YFF0503700 and 2022YFF0503900)。
文摘Ultra-low-frequency(ULF) waves are ubiquitous in terrestrial and planetary environments, playing a crucial role in energy transfer and dissipation through wave–particle interactions within space plasmas. By performing a detailed event study in terms of particle distribution maps and wave–particle variable correlation maps, we report that ULF waves observed by the Mars Atmosphere and Volatile EvolutioN(MAVEN) spacecraft in the Martian foreshock can effectively modulate the suprathermal electron fluxes by the magnetic field fluctuations. In particular, the variations in electron fluxes at energies of ~10–100 eV are significant in the perpendicular direction, showing good relationships with changes in the wave field strength characterized by a correlation coefficient ~0.8. These findings demonstrate the generality of interactions of ULF waves with electrons, even at these low energies, highlighting the importance of such processes throughout the heliosphere.
文摘Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.
基金supported by the National Key Research and Development Program of China(2017YFA0206701)the National Natural Science Foundation of China(51825201)。
文摘Rationally designed oxygen evolution reaction(OER)catalysts with structural and compositional superiorities are essential for energy-related electrocatalytic techniques.Transition-metal phosphides have been used as promising electrocatalysts for OER.Incorporating heteroatoms into the lattice can induce lattice distortion and redistribution of electron density,consequently modifying the electronic structure and improving catalytic performance.Herein,Fe-and S-substituted Ni_(2)P uniformly dispersed throughout porous carbon substrate(Ni-Fe-P-S@C)was rationally designed through transformation from the pre-synthesized NiFe-metal organic frameworks(NiFe-MOFs)by partial sulfurization and subsequent phosphorization process.Experimental results and density functional theory calculations showed that Fe and S incorporation could modulate the electronic structure of Ni_(2)P and alter the adsorption free energies of reaction intermediates,contributing to admirable electrocatalytic activity and stability toward OER.Notably,the in-situ formed partially oxidized surface was vital to further improve the local environment.This proposed cation-and anion-substitution strategy will bring new inspiration to boost the electrocatalytic performance of transition-metal-based electrocatalysts for energy conversion applications.
基金We acknowledge the financial support from the National Natural Science Foundation of China(Nos.U1662104 and 21576288).
文摘Large-scale electrolysis of water to produce high-purity hydrogen is one of the effective ways to solve the energy crisis and environmental pollution problems.However,efficient,cheap and stable catalysts are one of the bottlenecks for industrial application in water splitting.Herein,a facile one-step hydrothermal process was applied to fabricate Mn-doped nickel ferrite nanosheets(Mn-NiFe_(2)O_(4))which shown a low overpotential of 200 mV at 50 mA·cm^(-2)and a small Tafel slope of 47 mV·dec^(-1),together with a prominent turnover frequency(TOF)value(0.14 s^(-1))and robust stability.The in-situ UV-vis spectroscopy unveiled the surface reconstruction to generate NiOOH as active sites during oxygen evolution reaction(OER).The excellent electrocatalytic activity of Mn-NiFe_(2)O_(4)is attributed to the vertically grown nanosheets for exposure more active sites,rich oxygen vacancies,and the hybridization between Ni 3d and O 2p orbitals caused by Mn doping.This work should provide a facile strategy by Mn-doping to simultaneously engineer oxygen vacancies and electronic structure for synergistically triggering oxygen evolution reaction.
基金support from the Chinese Scholarship Council(201706220080)for W.H.the Natural Science Foundation of Hunan Province(2019JJ50526)for C.P.+1 种基金The Danish Council for Independent Research for the YDUN project(DFF 4093-00297)to J.Z.Villum Experiment(grant No.35844)for X.X.
文摘Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.
基金supported by National Natural Science Foundation of China(no.21978030),and also sponsored by the Chinese Ministry of Education via the Program for New Century Excellent Talents in University(no.NCET-12-0079).
文摘Developing an efficientmethod to improve the photocatalytic efficiency of graphitic carbon nitride(g-C3 N4)is of great significance for solar H2 production.Electronic structure modulation has been considered one of the most crucial strategies to improving the photocatalytic efficiency of g-C_(3)N_(4),but how to efficiently modulate its electronic structure remains a huge challenge.Herein,we,for the first time,report a facile and highly-efficient approach to modulating the electronic structure of g-C_(3)N_(4)through single Ag atom implantation with a Ag_(1)-N_(3)coordination configuration into the g-C_(3)N_(4)framework.
基金financial support provided by National Natural Science Foundation of China(52303283,52372232,52064049)the Major Science and Technology Projects of Yunnan Province(202302AB080019-3)+2 种基金National Natural Science Foundation of Yunnan Province(202301AS070040,202401AU070201)the Analysis and Measurements Center of Yunnan University for the sample testing servicethe Electron Microscope Center of Yunnan University for the support of this work.
文摘Regulation the electronic density of solid-state electrolyte by donor–acceptor(D–A)system can achieve highly-selective Li^(+)transportation and conduction in solid-state Li metal batteries.This study reports a high-performance solid-state electrolyte thorough D–A-linked covalent organic frameworks(COFs)based on intramolecular charge transfer interactions.Unlike other reported COFbased solid-state electrolyte,the developed concept with D–A-linked COFs not only achieves electronic modulation to promote highly-selective Li^(+)migration and inhibit Li dendrite,but also offers a crucial opportunity to understand the role of electronic density in solid-state Li metal batteries.The introduced strong electronegativity F-based ligand in COF electrolyte results in highlyselective Li^(+)(transference number 0.83),high ionic conductivity(6.7×10^(-4)S cm^(−1)),excellent cyclic ability(1000 h)in Li metal symmetric cell and high-capacity retention in Li/LiFePO_(4)cell(90.8%for 300 cycles at 5C)than substituted C-and N-based ligands.This is ascribed to outstanding D–A interaction between donor porphyrin and acceptor F atoms,which effectively expedites electron transferring from porphyrin to F-based ligand and enhances Li^(+)kinetics.Consequently,we anticipate that this work creates insight into the strategy for accelerating Li^(+)conduction in high-performance solid-state Li metal batteries through D–A system.
基金supported by the Key Projects of Intergovernmental International Cooperation in the Key R&D programs of the Ministry of Science and Technology of China(No.2021YFE0115800)the National Science Funding Committee of China(No.U20A20250)+1 种基金the Programs of the Science and Technology of Yulin City(No.CXY-2023-ZX04)the funding support from Shccig-Qinling Program.
文摘Solving the problem of aggregation and nonuniform dispersion of platinum(Pt)nanoparticles(NPs)is the key to obtaining high catalytic activity.Graphene aerogels(GAs)with large accessible specific surface area and abundant surface defects are considered to be excellent substrate materials for reducing Pt agglomeration and enhancing catalytic activity.Herein,Pt-based GA composites(Pt-GA-x)featuring homogeneous particle dispersion and high activity were successfully synthesized through a one-step reduction method.Fourier transform infrared(FTIR),Raman,and X-ray photoelectron spectroscopy(XPS)test results indicate that the presence of a large number of oxygen-containing functionalities in GA for anchoring Pt NPs,and the interaction with GA produces electronically structured Pt and defect-rich GA substrates.The obtained electrocatalyst Pt-GA-2 possesses a large specific surface area(443.46 m^(2)·g^(−1)),low Pt loading(3.08 wt%),and uniformly dispersed Pt NPs(average 42 nm).As an advanced hydrogen evolution reaction(HER)electrocatalyst,an overpotential of 34 mV is achieved at a current density of 10 mA·cm^(−2)in 0.5 M H_(2)SO_(4)electrolyte,together with a low Tafel slope of 33.2 mV·dec^(−1).Hence,high mass activity(5623 mA·mgPt^(−1))and turnover frequency(TOF=2.57 s^(−1)at η=100 mV)can be obtained,which are 6.81 and 6.76 times higher than those of commercial Pt/C catalysts.All these are attributed to enormous surface defects over GA and electron enrichment on Pt NPs.The present study highlights the unique advantages of GA in electrochemical energy conversion and provides new avenues to fabricate advanced HER electrocatalysts.
基金funded by the National Natural Science Foundation of China(No.52202446)the Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)+2 种基金the Young Elite Scientists Sponsorship Program by BAST(No.BYESS2023050)the Beijing Association for Science and Technology’s Golden-Bridge Seed Funding Program(No.ZZ22042)the Fundamental Research Funds for the Central Universities of China。
文摘Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.
基金Fok Ying Tung Education Foundation(No.91058)the Natural Science Foundation of High Education Institutions of Jiangsu Province(No.08KJD470004)Qing Lan Project of Jiangsu Province of 2008
文摘High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-IPEM）, consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management.
基金financially supported by the NSFC-Yunnan Joint Foundation(U2002213)the Double Tops Joint Fund of the Yunnan Science and Technology Bureau and Yunnan University(2019FY003025)the‘Double-First Class’University Construction Project(C176220100042 and CZ21623201)。
文摘The biggest challenge is to develop a low cost and readily available catalyst to replace expensive commercial Pt/C for efficient electrochemical oxygen reduction reaction(ORR).In this research,closo-[B_(12)H_(12)]^(2−)and 1,10-phenanthroline-iron complexes were introduced into the porous metal-organic framework by impregnation method,and further annealing treatment achieved the successful anchoring of single-atom-Fe in B-doped CN Matrix(FeN4CB).The ORR activity of FeN4CB is comparable to the widely used commercial 20 wt%Pt/C.Where the half-wave potential(E_(1/2))in alkaline medium up to 0.84 V,and even in the face of challenging ORR in acidic medium,the E_(1/2)of ORR driven by FeN4CB is still as high as 0.81 V.When FeN4CB was used as air cathode,the open circuit voltage of Zn-air battery reaches 1.435 V,and the power density and specific capacity are as high as 177 mW cm^(−2)and 800 mAh g_(Zn)^(−1)(theoretical value:820 mAh g_(Zn)^(−1)),respectively.The dazzling point of FeN4CB also appears in the high ORR stability,whether in alkaline or acidic media,E_(1/2)and limiting current density are still close to the initial value after 5000 times cycles.After continuously running the charge-discharge test for 220 h,the charge voltage and discharge voltage of the rechargeable zinc-air battery with FeN4CB as the air cathode maintained the initial state.Density functional theory calculations reveals that introducing B atom to Fe–N4–C can adjust the electronic structure to easily break O=O bond and significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.
文摘Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide(WS_(2))is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene(AHE),yet remains a major challenge.Herein,we report that by substituting a W atom of WS_(2) with a series of transition metal atoms,sulfur vacancy-confined Cu in the WS_(2) basal plane(Cu@WS_(2)-Sv)is theoretically screened as a superior non-noble metal-based catalyst with higher activity,selectivity,and stability for the AHE than other candidates.The co-adsorption of C_(2)H_(2) and H_(2) and hydrogenation of C_(2)H_(3)^(*) to C_(2)H_(4)^(*) are revealed as the key steps establishing a volcano-like activity trend among the candidates,which present Cu@WS_(2)-Sv as the optimum catalyst combined with molecular dynamics and reaction kinetics analyses.The kinetically more favorable desorption of C_(2)H_(4) than the over hydrogenation path validates a higher selectivity toward C_(2)H_(4) over C_(2)H_(6).Furthermore,a machine-learning model reveals the significant effect of d-electron number and electronegativity of the metal heteroatoms in modulating the AHE activity.
