7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because...7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because of its limited machining space,bad environment and large elongation induced low stiffness.To reduce vibration and improve machined surface quality,a particle damping boring bar,filled with particles in its inside damping block,is designed based on the theory of vibration control.The theoretical damping coefficient is determined,then the boring bar structure is designed and trial-manufactured.Experimental studies through impact testing show that cemented carbide particles with a diameter of 5 mm and a filling rate of 70% achieve a damping ratio of 19.386%,providing excellent vibration reduction capabilities,which may reduce the possibility of boring vibration.Then,experiments are setup to investigate its vibration reduction performance during deep hole boring of 7075 aluminum alloy.To observe more obviously,severe working conditions are adopted and carried out to acquire the time domain vibration signal of the head of the boring bar and the surface morphologies and roughness values of the workpieces.By comparing different experimental results,it is found that the designed boring bar could reduce the maximum vibration amplitude by up to 81.01% and the surface roughness value by up to 47.09% compared with the ordinary boring bar in two sets of experiments,proving that the designed boring bar can effectively reduce vibration.This study can offer certain valuable insights for the machining of this material.展开更多
This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode ...This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode positive(DCEP)polarities yielded crack-free partial penetration welds for6 mm thick AZ31B alloy sheet.Welding under direct current electrode negative(DCEN)polarity with identical parameters as that for AC and DCEP resulted in full penetration welds that had microcracks.Defect-free full-penetration welds could be accomplished with pulse GTA welding using DCEN polarity at a pulse frequency of 1 Hz with a pulse duration ratio of 1:1.The resultant DCEN P 1:1 weld metal had a microstructure finer than the conventional DCEN weld.Welds produced with pulse duration ratios of 1:2and 1:4 lacked penetration but had a much finer microstructures because of the lower heat input.The arc constriction by the high frequency pulsing in the Activ Arc■-High frequency(AA-HF)mode welding was responsible for deeper penetration.Welds produced under DCEN pulsing and AA-HF conditions had hardness higher than conventional DCEN,DCEP and AC GTA welds,attributed to the finer microstructure.AA-HF GTA welding produced defect free deeper penetration welds with good microstructural features/mechanical properties and also gave an advantage of 50%enhanced productivity when welded at1500 Hz.展开更多
Electrochemical reduction of NO_(2)-to NH_(3)(NO_(2)-RR) is recognized as an appealing approach for achieving renewable NH_(3)synthesis and waste NO_(2)-removal.Herein,we report isolated Bi alloyed Ru (Bi1Ru) as an ef...Electrochemical reduction of NO_(2)-to NH_(3)(NO_(2)-RR) is recognized as an appealing approach for achieving renewable NH_(3)synthesis and waste NO_(2)-removal.Herein,we report isolated Bi alloyed Ru (Bi1Ru) as an efficient NO_(2)-RR catalyst.Theoretical calculations and in situ electrochemical measurements reveal the creation of Bi1-Ru dual sites which can remarkably promote NO_(2)-activation and suppress proton adsorption,while accelerating the NO_(2)-RR protonation energetics to render a high NO_(2)--to-NH_(3)conversion efficiency.Remarkably,Bi1Ru assembled in a flow cell delivers an NH_(3)yield rate of 1901.4μmol h^(-1)cm^(-2)and an NH_(3)-Faradaic efficiency of 94.3%at an industrial-level current density of 324.3 mA cm^(-2).This study offers new perspectives for designing and constructing p-block single-atom alloys as robust and high-current-density NO_(2)-RR catalysts toward the ammonia electrosynthesis.展开更多
The effects of rare earth Lanthanum on the microstructure, the physical property and the microhardness of Ag-Cu-Ti solder alloy are studied. Experimental results indicate that the addition of Lanthanum can evidently i...The effects of rare earth Lanthanum on the microstructure, the physical property and the microhardness of Ag-Cu-Ti solder alloy are studied. Experimental results indicate that the addition of Lanthanum can evidently improve the wettability and the microhardness of Ag-Cu-Ti solder alloy. Analysis results show that the increase in microhardness is related to the refining and uniform distribution of the intermetallic compounds. Proper content of Lanthanum added in Ag-Cu-Ti alloy solder can be controlled below 0.5% in mass percent.展开更多
The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research focus.This paper provides a comprehensive review of the synergistic effects on the third-and fou...The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research focus.This paper provides a comprehensive review of the synergistic effects on the third-and fourth-generation fission nuclear energy structural materials used in pressurized water reactors and molten salt reactors.The competitive mechanisms of multiple influencing factors,such as the irradiation dose,corrosion type,and environmental temperature,are summarized in this paper.Conceptual approaches are proposed to alleviate the synergistic damage caused by irradiation and corrosion,thereby promoting in-depth research in the future and solving this key challenge for the structural materials used in reactors.展开更多
The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple ...The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.展开更多
The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is res...The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is responsible for the adsorption and activation of CO_(2)and the generation of CO and H2via side reactions often lead to poor efficiency and low selectivity of the catalyst.Herein,Cu,Pd,and PdCu metal clusters cocatalyst-anchored defective TiO_(2)nanotubes(Cu/TiO_(2)-SBO,Pd/TiO_(2)-SBO,and Pd1Cu1/TiO_(2)-SBO)were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO_(2)to CH_(4).The Pd1Cu1/TiO_(2)-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO_(2)into CH_(4).More interestingly,the product selectivity of CH_(4)reaches up to 100%with a rate of 25μmol g^(-1)h^(-1).In-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)simulations indicate that the main reasons for the high selectivity of CH_(4)are attributed to the PdCu alloy and oxygen vacancies,which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates.Moreover,due to the tunable d-band center of the Cu site in the PdCu alloy,the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions.Hopefully,the current study will provide insight into the development of new,highly selective photocatalysts for the visible light-catalytic reduction of CO_(2)into CH_(4).展开更多
Materials for deep-ultraviolet(DUV)light emission are extremely rare,significantly limiting the development of efficient DUV light-emitting diodes.Here we report CsMg(I_(1−x)Br_(x))_(3) alloys as potential DUV light e...Materials for deep-ultraviolet(DUV)light emission are extremely rare,significantly limiting the development of efficient DUV light-emitting diodes.Here we report CsMg(I_(1−x)Br_(x))_(3) alloys as potential DUV light emitters.Based on rigorous first-principles hybrid functional calculations,we find that CsMgI_(3) has an indirect bandgap,while CsMgBr_(3) has a direct bandgap.Further,we employ a band unfolding technique for alloy supercell calculations to investigate the critical Br concentration in CsMg(I_(1−x)Br_(x))_(3) associated with the crossover from an indirect to a direct bandgap,which is found to be∼0.36.Thus,CsMg(I_(1−x)Br_(x))_(3) alloys with 0.366≤6≤1 cover a wide range of direct bandgap(4.38–5.37 eV;284–231 nm),falling well into the DUV regime.Our study will guide the development of efficient DUV light emitters.展开更多
Compared to the commercial soft-magnetic alloys,the high saturation magnetic flux density(Bs)and low coercivity(Hc)of post-developed novel nanocrystalline alloys tend to realize the miniaturization and lightweight of ...Compared to the commercial soft-magnetic alloys,the high saturation magnetic flux density(Bs)and low coercivity(Hc)of post-developed novel nanocrystalline alloys tend to realize the miniaturization and lightweight of electronic products,thus attracting great attention.In this work,we designed a new FeNiBCuSi formulation with a novel atomic ratio,and the microstructure evolution and magnetic softness were investigated.Microstructure analysis revealed that the amount of Si prompted the differential chemical fluctuations of Cu element,favoring the different nucleation and growth processes ofα-Fe nanocrystals.Furthermore,microstructural defects associated with chemical heterogeneities were unveiled using the Maxwell-Voigt model with two Kelvin units and one Maxwell unit based on creeping analysis by nanoindentation.The defect,with a long relaxation time in relaxation spectra,was more likely to induce the formation of crystal nuclei that ultimately evolved into theα-Fe nanocrystals.As a result,Fe_(84)Ni_(2)B_(12.5)Cu_(1)Si_(0.5)alloy with refined uniform nanocrystalline microstructure exhibited excellent magnetic softness,including a high B_(s)of 1.79 T and very low H_(c)of 2.8 A/m.Our finding offers new insight into the influence of activated defects associated with chemical heterogeneities on the microstructures of nanocrystalline alloy with excellent magnetic softness.展开更多
Mg-Gd alloy particle has exhibited its unique combustion properties as the fuel of Mg/Teflon/Viton(MTV).Mg-Gd alloy/Teflon/Viton(MGTV)could burn at lower ambient pressure than MTV.To further investigate the reaction o...Mg-Gd alloy particle has exhibited its unique combustion properties as the fuel of Mg/Teflon/Viton(MTV).Mg-Gd alloy/Teflon/Viton(MGTV)could burn at lower ambient pressure than MTV.To further investigate the reaction of MGTV in air,it was investigated via thermo gravity-differential scanning calorimetry(TG-DSC).Meanwhile,the morphologies and element distributions on the alloy surface during the reaction of MGTV in air were investigated via scanning electronic microscope-mapping-electronic differential spectrometer.Meanwhile,a similar experimental protocol on the Mg-Gd alloy particle during oxidation was also applied.The results showed that owning to a protective oxide shell,the onset oxidation temperature of Mg-Gd alloy is higher than Mg.However,the onset oxidation temperature of the exceeded Mg-Gd alloy in MGTV is significantly lower than that of the exceeded Mg in MTV.It was due to the existence of GdOF,which could significantly lower the oxidation temperature of the exceeded fuel.Furthermore,a possible reaction mechanism was proposed.The fascinating oxidation properties of Mg-Gd alloy suggested its promising applications in energetic materials.展开更多
Since the superior mechanical,chemical and physical properties of high-entropy alloys(HEAs)were discovered,they have gradually become new emerging candidates for renewable energy applications.This review presents the ...Since the superior mechanical,chemical and physical properties of high-entropy alloys(HEAs)were discovered,they have gradually become new emerging candidates for renewable energy applications.This review presents the novel applications of HEAs in thermoelectric energy conversion.Firstly,the basic concepts and structural properties of HEAs are introduced.Then,we discuss a number of promising thermoelectric materials based on HEAs.Finally,the conclusion and outlook are presented.This article presents an advanced understanding of the thermoelectric properties of HEAs,which provides new opportunities for promoting their applications in renewable energy.展开更多
Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems.The search for refrigeration materials displaying a unique combination of pronounced caloric effect...Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems.The search for refrigeration materials displaying a unique combination of pronounced caloric effect,low hysteresis,and high reversibility on phase transformation was very active in recent years.Here,we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment,with very low stress hysteresis(6.3 MPa)under a large applied strain(5%).Large adiabatic temperature changes(△T_(max)=16.3 K atε=5%)and moderate COP_(mater)values(maximum COP_(mater)=11.8 atε=2%)were achieved.The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.展开更多
The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learni...The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.展开更多
The effect of Mn element on shock response of CoCrFeNiMn_(x) high entropy alloys(HEAs)are investigated using molecular dynamics simulations.Structural analysis shows that Mn-rich CoCrFeNiMn_(x) HEA has a larger averag...The effect of Mn element on shock response of CoCrFeNiMn_(x) high entropy alloys(HEAs)are investigated using molecular dynamics simulations.Structural analysis shows that Mn-rich CoCrFeNiMn_(x) HEA has a larger average atomic volume.The elastic properties of CoCrFeNiMn_(x) HEAs under various hydrostatic pressures are studied,revealing that the elastic modulus decreases with increasing of Mn content.The shock thermodynamic parameters are quantitatively analyzed.The Mn-dependent shock Hugoniot relationship of CoCrFeNiMn_(x) HEAs is obtained:Us=1.25+(5.21–0.011x)Up.At relatively high shock pressure,the increase in Mn content promotes the formation of clustered BCC structures and hinders the development of dislocations.In addition,more FCC structures in Mn-rich CoCrFeNiMn_(x) HEAs transform into disordered structures during spallation.Spall strength decreases with increasing Mn content.This study can provide a reference for the design and application of CoCrFeNiMn HEAs under shock loading.展开更多
A series of high-entropy alloys(HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method.In order to study the irradiation evolution of helium bubbles in...A series of high-entropy alloys(HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method.In order to study the irradiation evolution of helium bubbles in the FeCoNiCrbased HE As with γ' precipitates,these samples are irradiated by 100-keV helium ions with a fluence of 5 × 10^(20) ions/m^(2) at 293 K and 673 K,respectively.And the samples irradiated at room temperature are annealed at different temperatures to examine the diffusion behavior of helium bubbles.Transmission electron microscope(TEM) is employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles.Experimental results reveal that nanosized,spherical,dispersed,coherent,and ordered L1_(2)-type Ni_(3)Ti γ' precipitations are introduced into FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs by means of ageing treatments at temperatures between 1073 K and 1123 K.Under the ageing treatment conditions adopted in this work,γ' nanoparticles are precipitated in FeCoNiCr(Ni_(3)Ti)_(0.1) HE As,with average diameters of 15.80 nm,37.09 nm,and 62.50 nm,respectively.The average sizes of helium bubbles observed in samples after 673-K irradiation are 1.46 nm,1.65 nm,and 1.58 nm,respectively.The improvement in the irradiation resistance of FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs is evidenced by the diminution in bubbles size.Furthermore,the FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs containing γ' precipitates of 15.8 nm exhibits the minimum size and density of helium bubbles,which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries.Subsequently,annealing experiments conducted after 293-K irradiation indicate that HEAs containing precipitated phases exhibits smaller apparent activation energy(E_(a)) for helium bubbles,resulting in larger helium bubble size.This study provides guidance for improving the irradiation resistance of L1_(2)-strengthened high-entropy alloy.展开更多
Solid polymer electrolytes(SPEs)are urgently required to achieve practical solid-state lithium metal batteries(LMBs)and lithium-ion batteries(LIBs),Herein,we proposed a mechanism for modulating interfacial conduction ...Solid polymer electrolytes(SPEs)are urgently required to achieve practical solid-state lithium metal batteries(LMBs)and lithium-ion batteries(LIBs),Herein,we proposed a mechanism for modulating interfacial conduction and anode interfaces in high-concentration SPEs by LiDFBOP.Optimized electrolyte exhibits superior ionic conductivity and remarkable interface compatibility with salt-rich clusters:(1)polymer-plastic crystal electrolyte(P-PCE,TPU-SN matrix)dissociates ion pairs to facilitate Li+transport in the electrolyte and regulates Li^(+)diffusion in the SEI.The crosslinking structure of the matrix compensates for the loss of mechanical strength at high-salt concentrations;(2)dual-anion TFSI^(-)_(n)-DFBOP^(-)_(m)in the Li^(+)solvation sheath facilitates facile Li^(+)desolvation and formation of salt-rich clusters and is conducive to the formation of Li conductive segments of TPU-SN matrix;(3)theoretical calculations indicate that the decomposition products of LiDFBOP form SEI with lower binding energy with LiF in the SN system,thereby enhancing the interfacial electrochemical redox kinetics of SPE and creating a solid interface SEI layer rich in LiF.As a result,the optimized electrolyte exhibits an excellent ionic conductivity of9.31×10^(-4)S cm^(-1)at 30℃and a broadened electrochemical stability up to 4.73 V.The designed electrolyte effectively prevents the formation of Li dendrites in Li symmetric cells for over 6500 h at0.1 mA cm^(-2).The specific Li-Si alloy-solid state half-cell capacity shows 711.6 mAh g^(-1)after 60 cycles at 0.3 A g^(-1).Excellent rate performance and cycling stability are achieved for these solid-state batteries with Li-Si alloy anodes and NCM 811 cathodes.NCM 811‖Prelithiated silicon-based anode solid-state cell delivers a discharge capacity of 195.55 mAh g^(-1)and a capacity retention of 97.8%after 120 cycles.NCM 811‖Li solid-state cell also delivers capacity retention of 84.2%after 450 cycles.展开更多
The thermal-elastic martensitic transformation from high-temperature Ni_(2)In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in MnMX(M=Ni or Co,and X=Ge or Si)al...The thermal-elastic martensitic transformation from high-temperature Ni_(2)In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in MnMX(M=Ni or Co,and X=Ge or Si)alloys.However,the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear.In this work,the hexagonal-orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated.One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature(M_(s)).With the the sample cooing to M_(s),the laths turn broader,indicating that the martensitic transformation starts from these pre-existing orthorhombic laths.Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal-orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the preexisting orthorhombic laths.The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent.Therefore,the orthorhombic martensite can take these pre-existing laths as embryos and grow up.This work implies that the martensitic transformation in MnNiSi_(1-x)(CoNiGe)_(x) alloy is initiated by orthorhombic embryos.展开更多
Transition metals like Au,Ag,and Cu have been reported to be quite active for CO_(2) reduction.In this study,we use density functional theory(DFT)calculation to investigate the electronic structure and catalytic perfo...Transition metals like Au,Ag,and Cu have been reported to be quite active for CO_(2) reduction.In this study,we use density functional theory(DFT)calculation to investigate the electronic structure and catalytic performance of Au,Ag,Cu and their alloys for CO_(2) reduction reaction(CO_(2)RR).Theoretical calculations identified the combination of Ag,Cu,and Au in a face-centered cubic(fcc)alloy as an outstanding electrocatalyst for CO_(2) reduction to CO,with Cu as the active site.The d-orbital projected density of state(PDOS)profile suggests that alloying alters the electronic structure of the Cu site,thereby affecting the Gibbs free energy change for the formation of*COOH intermediate(ΔG_(*COOH)).To demonstrate the theoretical prediction experimentally,we employ a top-down dealloying approach to synthesize a nanoporous structured AgCuAu alloy(NP-Ag_(5)Cu_(5)Au_(5)).Electrochemical experiments validate that the ternary alloy catalyst is clearly better than unary and binary catalysts,showing a Faradaic efficiency(FE)for CO over 90%across a broad potential range of 0.6 V,with a peak of approximately 96%at-0.573 V vs.RHE.This study underscores the potential of multi-component alloys in CO_(2)RR and establishes a theoretical basis for designing efficient catalysts for CO_(2) utilization.展开更多
Achieving composition tunability and structure editability of nanoalloys with high level strain may be an efficient strategy to remarkably boost catalytic performance toward oxygen evolution reaction(OER)in acidic wat...Achieving composition tunability and structure editability of nanoalloys with high level strain may be an efficient strategy to remarkably boost catalytic performance toward oxygen evolution reaction(OER)in acidic water oxidation.Herein,lotus root-like RuIr alloys with native micro-strain were constructed by an epitaxial growth of Ru-richened hcp-(0001)branches on Ir-richened fcc-(111)seeds using a polyol thermal synthesis strategy.The resultant Ru_(60)Ir_(40) alloy shows an OER overpotential of 197 mV at 10 mA cm^(-2) and a Tafel slope of 46.59 mV dec^(-1),showing no obvious activity decay for 80 h continuous chronopotentiometry test in 0.5 M H_(2)SO_(4).The related characterizations including X-ray absorption fine structure(XAFS)spectroscopy and density functional theory(DFT)calculations show that that the remarkably improved activity of the lotus root-like alloy can be attributed to the(0001)facet-triggered strain,which can efficiently optimize the electronic band structure of the active metal and the weakening of the chemisorption of oxygen-containing substances to boost OER electrocatalysis.Therefore,this work provides a new strategy to designing a class of advanced electrocatalysts with high strain using diverse nanostructures as building materials for carbon-free clean energy conversion systems.展开更多
Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in ter...Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation.Herein,the PtFe alloy nanoparticles(NPs) with small particle size(~4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios(Pt_(1)Fe_(2)/C,Pt_(3)Fe_(4)/C,Pt_(1)Fe_(1)/C,and Pt_(2)Fe_(1)/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction(MOR).The optimal atomic ratio of Pt/Fe for the MOR is 1:2,and the mass activity of Pt_(1)Fe_(2)/C(5.40 A mg_(Pt)^(-1)) is 13.5 times higher than that of conventional commercial Pt/C(Pt/C-JM)(0.40 A mg_(Pt)^(-1)).The introduction of Fe into the Pt lattice forms the PtFe alloy phase,and the electron density of Pt is reduced after forming the PtFe alloy.In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR.The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites,promoting the cleavage of C-O bonds with good selectivity of CO_(2)(58.1%).Moreover,the Pt_(1)Fe_(2)/C catalyst exhibits higher CO tolerance,methanol electrooxidation activity,and long-term stability than other Pt_(x)Fe_(y)/C catalysts.展开更多
基金supported by the Scientific Research Program of Tianjin Education Committee(No.2022ZD030)。
文摘7075 aluminum alloy is often used as an important load-bearing structure in aircraft industry due to its superior mechanical properties.During the process of deep hole boring,the boring bar is prone to vibrate because of its limited machining space,bad environment and large elongation induced low stiffness.To reduce vibration and improve machined surface quality,a particle damping boring bar,filled with particles in its inside damping block,is designed based on the theory of vibration control.The theoretical damping coefficient is determined,then the boring bar structure is designed and trial-manufactured.Experimental studies through impact testing show that cemented carbide particles with a diameter of 5 mm and a filling rate of 70% achieve a damping ratio of 19.386%,providing excellent vibration reduction capabilities,which may reduce the possibility of boring vibration.Then,experiments are setup to investigate its vibration reduction performance during deep hole boring of 7075 aluminum alloy.To observe more obviously,severe working conditions are adopted and carried out to acquire the time domain vibration signal of the head of the boring bar and the surface morphologies and roughness values of the workpieces.By comparing different experimental results,it is found that the designed boring bar could reduce the maximum vibration amplitude by up to 81.01% and the surface roughness value by up to 47.09% compared with the ordinary boring bar in two sets of experiments,proving that the designed boring bar can effectively reduce vibration.This study can offer certain valuable insights for the machining of this material.
文摘This work aimed to(i)understand conventional and pulse gas tungsten arc welding(GTAW)of AZ31B,and(ii)explore high frequency welding(100 Hz-1500 Hz).GTA welding with alternating current(AC)and direct current electrode positive(DCEP)polarities yielded crack-free partial penetration welds for6 mm thick AZ31B alloy sheet.Welding under direct current electrode negative(DCEN)polarity with identical parameters as that for AC and DCEP resulted in full penetration welds that had microcracks.Defect-free full-penetration welds could be accomplished with pulse GTA welding using DCEN polarity at a pulse frequency of 1 Hz with a pulse duration ratio of 1:1.The resultant DCEN P 1:1 weld metal had a microstructure finer than the conventional DCEN weld.Welds produced with pulse duration ratios of 1:2and 1:4 lacked penetration but had a much finer microstructures because of the lower heat input.The arc constriction by the high frequency pulsing in the Activ Arc■-High frequency(AA-HF)mode welding was responsible for deeper penetration.Welds produced under DCEN pulsing and AA-HF conditions had hardness higher than conventional DCEN,DCEP and AC GTA welds,attributed to the finer microstructure.AA-HF GTA welding produced defect free deeper penetration welds with good microstructural features/mechanical properties and also gave an advantage of 50%enhanced productivity when welded at1500 Hz.
基金Longyuan Youth Innovative and Entrepreneurial Talents ProjectProgram for Top Leading Talents of Gansu Province。
文摘Electrochemical reduction of NO_(2)-to NH_(3)(NO_(2)-RR) is recognized as an appealing approach for achieving renewable NH_(3)synthesis and waste NO_(2)-removal.Herein,we report isolated Bi alloyed Ru (Bi1Ru) as an efficient NO_(2)-RR catalyst.Theoretical calculations and in situ electrochemical measurements reveal the creation of Bi1-Ru dual sites which can remarkably promote NO_(2)-activation and suppress proton adsorption,while accelerating the NO_(2)-RR protonation energetics to render a high NO_(2)--to-NH_(3)conversion efficiency.Remarkably,Bi1Ru assembled in a flow cell delivers an NH_(3)yield rate of 1901.4μmol h^(-1)cm^(-2)and an NH_(3)-Faradaic efficiency of 94.3%at an industrial-level current density of 324.3 mA cm^(-2).This study offers new perspectives for designing and constructing p-block single-atom alloys as robust and high-current-density NO_(2)-RR catalysts toward the ammonia electrosynthesis.
基金the Natural Science Foundation of Jiangsu Province(BK2006723)the China Postdoc-toral Science Foundation(20060400282)~~
文摘The effects of rare earth Lanthanum on the microstructure, the physical property and the microhardness of Ag-Cu-Ti solder alloy are studied. Experimental results indicate that the addition of Lanthanum can evidently improve the wettability and the microhardness of Ag-Cu-Ti solder alloy. Analysis results show that the increase in microhardness is related to the refining and uniform distribution of the intermetallic compounds. Proper content of Lanthanum added in Ag-Cu-Ti alloy solder can be controlled below 0.5% in mass percent.
基金supported by the National Natural Science Foundation of China(Nos.12022515 and 11975304)the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.Y202063)。
文摘The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research focus.This paper provides a comprehensive review of the synergistic effects on the third-and fourth-generation fission nuclear energy structural materials used in pressurized water reactors and molten salt reactors.The competitive mechanisms of multiple influencing factors,such as the irradiation dose,corrosion type,and environmental temperature,are summarized in this paper.Conceptual approaches are proposed to alleviate the synergistic damage caused by irradiation and corrosion,thereby promoting in-depth research in the future and solving this key challenge for the structural materials used in reactors.
基金supported by the National Natural Science Foundation of China(52374301 and 22279030)the Fundamental Research Funds for the Central Universities(N2223037)+1 种基金Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021201)the Performance subsidy fund for the Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.
基金the financial support from the Program for Innovative Research Team in University of Henan Province(21IRTSTHN009)Science and Technology Fund of Henan Province(225200810051)Natural Science Foundation of Henan Province(222300420406)。
文摘The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is responsible for the adsorption and activation of CO_(2)and the generation of CO and H2via side reactions often lead to poor efficiency and low selectivity of the catalyst.Herein,Cu,Pd,and PdCu metal clusters cocatalyst-anchored defective TiO_(2)nanotubes(Cu/TiO_(2)-SBO,Pd/TiO_(2)-SBO,and Pd1Cu1/TiO_(2)-SBO)were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO_(2)to CH_(4).The Pd1Cu1/TiO_(2)-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO_(2)into CH_(4).More interestingly,the product selectivity of CH_(4)reaches up to 100%with a rate of 25μmol g^(-1)h^(-1).In-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)simulations indicate that the main reasons for the high selectivity of CH_(4)are attributed to the PdCu alloy and oxygen vacancies,which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates.Moreover,due to the tunable d-band center of the Cu site in the PdCu alloy,the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions.Hopefully,the current study will provide insight into the development of new,highly selective photocatalysts for the visible light-catalytic reduction of CO_(2)into CH_(4).
基金supported by the National Natural Science Foundation of China(Grant Nos.52172136,12088101,11991060,and U2230402)。
文摘Materials for deep-ultraviolet(DUV)light emission are extremely rare,significantly limiting the development of efficient DUV light-emitting diodes.Here we report CsMg(I_(1−x)Br_(x))_(3) alloys as potential DUV light emitters.Based on rigorous first-principles hybrid functional calculations,we find that CsMgI_(3) has an indirect bandgap,while CsMgBr_(3) has a direct bandgap.Further,we employ a band unfolding technique for alloy supercell calculations to investigate the critical Br concentration in CsMg(I_(1−x)Br_(x))_(3) associated with the crossover from an indirect to a direct bandgap,which is found to be∼0.36.Thus,CsMg(I_(1−x)Br_(x))_(3) alloys with 0.366≤6≤1 cover a wide range of direct bandgap(4.38–5.37 eV;284–231 nm),falling well into the DUV regime.Our study will guide the development of efficient DUV light emitters.
基金Project supported by the Anhui Provincial Natural Science Foundation(Grant No.2208085QE121)the Key Research&Development Plan of Anhui Province(Grant No.2022a05020016)+1 种基金the University Natural Science Research Project of Anhui Province(Grant No.2023AH051084)the National Natural Science Foundation of China(Grant No.52071078)。
文摘Compared to the commercial soft-magnetic alloys,the high saturation magnetic flux density(Bs)and low coercivity(Hc)of post-developed novel nanocrystalline alloys tend to realize the miniaturization and lightweight of electronic products,thus attracting great attention.In this work,we designed a new FeNiBCuSi formulation with a novel atomic ratio,and the microstructure evolution and magnetic softness were investigated.Microstructure analysis revealed that the amount of Si prompted the differential chemical fluctuations of Cu element,favoring the different nucleation and growth processes ofα-Fe nanocrystals.Furthermore,microstructural defects associated with chemical heterogeneities were unveiled using the Maxwell-Voigt model with two Kelvin units and one Maxwell unit based on creeping analysis by nanoindentation.The defect,with a long relaxation time in relaxation spectra,was more likely to induce the formation of crystal nuclei that ultimately evolved into theα-Fe nanocrystals.As a result,Fe_(84)Ni_(2)B_(12.5)Cu_(1)Si_(0.5)alloy with refined uniform nanocrystalline microstructure exhibited excellent magnetic softness,including a high B_(s)of 1.79 T and very low H_(c)of 2.8 A/m.Our finding offers new insight into the influence of activated defects associated with chemical heterogeneities on the microstructures of nanocrystalline alloy with excellent magnetic softness.
文摘Mg-Gd alloy particle has exhibited its unique combustion properties as the fuel of Mg/Teflon/Viton(MTV).Mg-Gd alloy/Teflon/Viton(MGTV)could burn at lower ambient pressure than MTV.To further investigate the reaction of MGTV in air,it was investigated via thermo gravity-differential scanning calorimetry(TG-DSC).Meanwhile,the morphologies and element distributions on the alloy surface during the reaction of MGTV in air were investigated via scanning electronic microscope-mapping-electronic differential spectrometer.Meanwhile,a similar experimental protocol on the Mg-Gd alloy particle during oxidation was also applied.The results showed that owning to a protective oxide shell,the onset oxidation temperature of Mg-Gd alloy is higher than Mg.However,the onset oxidation temperature of the exceeded Mg-Gd alloy in MGTV is significantly lower than that of the exceeded Mg in MTV.It was due to the existence of GdOF,which could significantly lower the oxidation temperature of the exceeded fuel.Furthermore,a possible reaction mechanism was proposed.The fascinating oxidation properties of Mg-Gd alloy suggested its promising applications in energetic materials.
基金Project supported by the Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK20220407 and BK20220428)。
文摘Since the superior mechanical,chemical and physical properties of high-entropy alloys(HEAs)were discovered,they have gradually become new emerging candidates for renewable energy applications.This review presents the novel applications of HEAs in thermoelectric energy conversion.Firstly,the basic concepts and structural properties of HEAs are introduced.Then,we discuss a number of promising thermoelectric materials based on HEAs.Finally,the conclusion and outlook are presented.This article presents an advanced understanding of the thermoelectric properties of HEAs,which provides new opportunities for promoting their applications in renewable energy.
基金Project supported by the Science Fund of the Key Laboratory of Cryogenic Science and Technology(Grant Nos.CRYO20230203 and CRYO202106)the National Natural Science Foundation of China(Grant Nos.51872299 and 52071223)the National Key Research and Development Program of China(Grant No.2019YFA0704904)。
文摘Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems.The search for refrigeration materials displaying a unique combination of pronounced caloric effect,low hysteresis,and high reversibility on phase transformation was very active in recent years.Here,we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment,with very low stress hysteresis(6.3 MPa)under a large applied strain(5%).Large adiabatic temperature changes(△T_(max)=16.3 K atε=5%)and moderate COP_(mater)values(maximum COP_(mater)=11.8 atε=2%)were achieved.The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.
基金supported by the Southwest Institute of Technology and Engineering cooperation fund(Grant No.HDHDW5902020104)。
文摘The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.11802139).
文摘The effect of Mn element on shock response of CoCrFeNiMn_(x) high entropy alloys(HEAs)are investigated using molecular dynamics simulations.Structural analysis shows that Mn-rich CoCrFeNiMn_(x) HEA has a larger average atomic volume.The elastic properties of CoCrFeNiMn_(x) HEAs under various hydrostatic pressures are studied,revealing that the elastic modulus decreases with increasing of Mn content.The shock thermodynamic parameters are quantitatively analyzed.The Mn-dependent shock Hugoniot relationship of CoCrFeNiMn_(x) HEAs is obtained:Us=1.25+(5.21–0.011x)Up.At relatively high shock pressure,the increase in Mn content promotes the formation of clustered BCC structures and hinders the development of dislocations.In addition,more FCC structures in Mn-rich CoCrFeNiMn_(x) HEAs transform into disordered structures during spallation.Spall strength decreases with increasing Mn content.This study can provide a reference for the design and application of CoCrFeNiMn HEAs under shock loading.
基金Project support provided by the National Natural Science Foundation of China(Grant No.12075200)the National Key Research and Development Program of China(Grant No.2022YFB3706004)。
文摘A series of high-entropy alloys(HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method.In order to study the irradiation evolution of helium bubbles in the FeCoNiCrbased HE As with γ' precipitates,these samples are irradiated by 100-keV helium ions with a fluence of 5 × 10^(20) ions/m^(2) at 293 K and 673 K,respectively.And the samples irradiated at room temperature are annealed at different temperatures to examine the diffusion behavior of helium bubbles.Transmission electron microscope(TEM) is employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles.Experimental results reveal that nanosized,spherical,dispersed,coherent,and ordered L1_(2)-type Ni_(3)Ti γ' precipitations are introduced into FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs by means of ageing treatments at temperatures between 1073 K and 1123 K.Under the ageing treatment conditions adopted in this work,γ' nanoparticles are precipitated in FeCoNiCr(Ni_(3)Ti)_(0.1) HE As,with average diameters of 15.80 nm,37.09 nm,and 62.50 nm,respectively.The average sizes of helium bubbles observed in samples after 673-K irradiation are 1.46 nm,1.65 nm,and 1.58 nm,respectively.The improvement in the irradiation resistance of FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs is evidenced by the diminution in bubbles size.Furthermore,the FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs containing γ' precipitates of 15.8 nm exhibits the minimum size and density of helium bubbles,which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries.Subsequently,annealing experiments conducted after 293-K irradiation indicate that HEAs containing precipitated phases exhibits smaller apparent activation energy(E_(a)) for helium bubbles,resulting in larger helium bubble size.This study provides guidance for improving the irradiation resistance of L1_(2)-strengthened high-entropy alloy.
基金the support from the National Natural Science Foundation of China(Grant No.22179006)supported by the Beijing Natural Science Foundation(2244101)+1 种基金the National Natural Science Foundation of China(Grant No.52072036)the SINOPEC project(223128)。
文摘Solid polymer electrolytes(SPEs)are urgently required to achieve practical solid-state lithium metal batteries(LMBs)and lithium-ion batteries(LIBs),Herein,we proposed a mechanism for modulating interfacial conduction and anode interfaces in high-concentration SPEs by LiDFBOP.Optimized electrolyte exhibits superior ionic conductivity and remarkable interface compatibility with salt-rich clusters:(1)polymer-plastic crystal electrolyte(P-PCE,TPU-SN matrix)dissociates ion pairs to facilitate Li+transport in the electrolyte and regulates Li^(+)diffusion in the SEI.The crosslinking structure of the matrix compensates for the loss of mechanical strength at high-salt concentrations;(2)dual-anion TFSI^(-)_(n)-DFBOP^(-)_(m)in the Li^(+)solvation sheath facilitates facile Li^(+)desolvation and formation of salt-rich clusters and is conducive to the formation of Li conductive segments of TPU-SN matrix;(3)theoretical calculations indicate that the decomposition products of LiDFBOP form SEI with lower binding energy with LiF in the SN system,thereby enhancing the interfacial electrochemical redox kinetics of SPE and creating a solid interface SEI layer rich in LiF.As a result,the optimized electrolyte exhibits an excellent ionic conductivity of9.31×10^(-4)S cm^(-1)at 30℃and a broadened electrochemical stability up to 4.73 V.The designed electrolyte effectively prevents the formation of Li dendrites in Li symmetric cells for over 6500 h at0.1 mA cm^(-2).The specific Li-Si alloy-solid state half-cell capacity shows 711.6 mAh g^(-1)after 60 cycles at 0.3 A g^(-1).Excellent rate performance and cycling stability are achieved for these solid-state batteries with Li-Si alloy anodes and NCM 811 cathodes.NCM 811‖Prelithiated silicon-based anode solid-state cell delivers a discharge capacity of 195.55 mAh g^(-1)and a capacity retention of 97.8%after 120 cycles.NCM 811‖Li solid-state cell also delivers capacity retention of 84.2%after 450 cycles.
基金Project supported by the National Natural Science Foundation of China (Grant No.11974184)。
文摘The thermal-elastic martensitic transformation from high-temperature Ni_(2)In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in MnMX(M=Ni or Co,and X=Ge or Si)alloys.However,the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear.In this work,the hexagonal-orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated.One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature(M_(s)).With the the sample cooing to M_(s),the laths turn broader,indicating that the martensitic transformation starts from these pre-existing orthorhombic laths.Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal-orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the preexisting orthorhombic laths.The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent.Therefore,the orthorhombic martensite can take these pre-existing laths as embryos and grow up.This work implies that the martensitic transformation in MnNiSi_(1-x)(CoNiGe)_(x) alloy is initiated by orthorhombic embryos.
基金supported by Shenzhen Key Laboratory of Advanced Functional Carbon Materials Research and Comprehensive Application(No.ZDSYS20220527171407017)。
文摘Transition metals like Au,Ag,and Cu have been reported to be quite active for CO_(2) reduction.In this study,we use density functional theory(DFT)calculation to investigate the electronic structure and catalytic performance of Au,Ag,Cu and their alloys for CO_(2) reduction reaction(CO_(2)RR).Theoretical calculations identified the combination of Ag,Cu,and Au in a face-centered cubic(fcc)alloy as an outstanding electrocatalyst for CO_(2) reduction to CO,with Cu as the active site.The d-orbital projected density of state(PDOS)profile suggests that alloying alters the electronic structure of the Cu site,thereby affecting the Gibbs free energy change for the formation of*COOH intermediate(ΔG_(*COOH)).To demonstrate the theoretical prediction experimentally,we employ a top-down dealloying approach to synthesize a nanoporous structured AgCuAu alloy(NP-Ag_(5)Cu_(5)Au_(5)).Electrochemical experiments validate that the ternary alloy catalyst is clearly better than unary and binary catalysts,showing a Faradaic efficiency(FE)for CO over 90%across a broad potential range of 0.6 V,with a peak of approximately 96%at-0.573 V vs.RHE.This study underscores the potential of multi-component alloys in CO_(2)RR and establishes a theoretical basis for designing efficient catalysts for CO_(2) utilization.
基金supported by the National Natural Science Funds of China(Grant number 22278016)Science and technology planning project of Yunnan Precious Metals Laboratory(Grant number YPML-2023050204)。
文摘Achieving composition tunability and structure editability of nanoalloys with high level strain may be an efficient strategy to remarkably boost catalytic performance toward oxygen evolution reaction(OER)in acidic water oxidation.Herein,lotus root-like RuIr alloys with native micro-strain were constructed by an epitaxial growth of Ru-richened hcp-(0001)branches on Ir-richened fcc-(111)seeds using a polyol thermal synthesis strategy.The resultant Ru_(60)Ir_(40) alloy shows an OER overpotential of 197 mV at 10 mA cm^(-2) and a Tafel slope of 46.59 mV dec^(-1),showing no obvious activity decay for 80 h continuous chronopotentiometry test in 0.5 M H_(2)SO_(4).The related characterizations including X-ray absorption fine structure(XAFS)spectroscopy and density functional theory(DFT)calculations show that that the remarkably improved activity of the lotus root-like alloy can be attributed to the(0001)facet-triggered strain,which can efficiently optimize the electronic band structure of the active metal and the weakening of the chemisorption of oxygen-containing substances to boost OER electrocatalysis.Therefore,this work provides a new strategy to designing a class of advanced electrocatalysts with high strain using diverse nanostructures as building materials for carbon-free clean energy conversion systems.
基金supported by the National Natural Science Foundation of China(22162012 and 22202089)the Youth Jinggang Scholars Program in Jiangxi Province([2019]57)+6 种基金the Thousand Talents Plan of Jiangxi Province(jxsq2019201083)the Natural Science Foundation of Jiangxi Province for Distinguished Young Scholars(20224ACB213005)the Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology(JXUSTQJBJ2019002)the Research Foundation of Education Bureau of Jiangxi Province of China(GJJ210833)the Foundation of State Key Laboratory of Physical Chemistry of Solid Surfaces(202022)the China Postdoctoral Science Foundation(2021M693893)the Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(20212BCD42018)。
文摘Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation.Herein,the PtFe alloy nanoparticles(NPs) with small particle size(~4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios(Pt_(1)Fe_(2)/C,Pt_(3)Fe_(4)/C,Pt_(1)Fe_(1)/C,and Pt_(2)Fe_(1)/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction(MOR).The optimal atomic ratio of Pt/Fe for the MOR is 1:2,and the mass activity of Pt_(1)Fe_(2)/C(5.40 A mg_(Pt)^(-1)) is 13.5 times higher than that of conventional commercial Pt/C(Pt/C-JM)(0.40 A mg_(Pt)^(-1)).The introduction of Fe into the Pt lattice forms the PtFe alloy phase,and the electron density of Pt is reduced after forming the PtFe alloy.In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR.The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites,promoting the cleavage of C-O bonds with good selectivity of CO_(2)(58.1%).Moreover,the Pt_(1)Fe_(2)/C catalyst exhibits higher CO tolerance,methanol electrooxidation activity,and long-term stability than other Pt_(x)Fe_(y)/C catalysts.
