Proton exchange membrane （PEM） water electrolysis presents considerable advantages in green hydrogen ***,oxygen evolution reaction （OER） catalysts in PEM water electrolysis currently encounter several pressing cha...
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Proton exchange membrane （PEM） water electrolysis presents considerable advantages in green hydrogen ***,oxygen evolution reaction （OER） catalysts in PEM water electrolysis currently encounter several pressing challenges,including high noble metal loading,low mass activity,and inadequate durability,which impede their practical application and *** we report a self-constructed layered catalyst for acidic OER by directly using an Ir–Ta-based metallic glass as the matrix,featuring a nanoporous IrO2surface formed in situ on the amorphous Ir TaOxnanostructure during *** distinctive architecture significantly enhances the accessibility and utilization of Ir,achieving a high mass activity of 1.06 A mgIr-1at a 300 mV overpotential,13.6 and 31.2 times greater than commercial Ir/C and IrO2,*** catalyst also exhibits superb stability under industrial-relevant current densities in acid,indicating its potential for practical *** analyses reveal that the coordinated nature of the surface-active Ir species is effectively modulated through electronic interaction between Ir and Ta,preventing them from rapidly evolving into high valence states and suppressing the lattice oxygen ***,the underlying IrTaOxdynamically replenishes the depletion of surface-active sites through inward crystallization and selective dissolution,thereby ensuring the catalyst’s long-term durability.
In this work, we performed in situ nanoindentation in TEM to capture the real-time dislocation and twinning activities in pure Mg during loading and unloading. We demonstrated that the screw component of dislocations ...
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In this work, we performed in situ nanoindentation in TEM to capture the real-time dislocation and twinning activities in pure Mg during loading and unloading. We demonstrated that the screw component of dislocations glides continuously, while the edge components rapidly become sessile during loading. The twin tip propagation is intermittent, whereas the twin boundary migration is more continuous. During unloading, we observed the elastic strain relaxation causes both dislocation retraction and detwinning. Moreover,we note that the plastic zone comprised of dislocations in Mg is well-defined, which contrasts with the diffused plastic zones observed in face-centered cubic metals under the nanoindentation impressions. Additionally, molecular dynamics simulations were performed to study the formation and evolution of deformation-induced crystallographic defects at the early stages of indentation. We observed that,in addition to dislocations, the I1stacking fault bounded with a <1/2c+p> Frank loop can be generated from the plastic zone ahead of the indenter, and potentially serve as a nucleation source for abundant dislocations observed experimentally. These new findings are anticipated to provide new knowledge on the deformation mechanisms of Mg, which are difficult to obtain through conventional ex situ approaches. These observations may serve as a baseline for simulation work that investigate the dynamics of dislocation slip and twinning in Mg and alloys.
Mg-Zn-based alloys have been widely used in computer,communication,and consumer(3C)products due to excellent thermal ***,it is still a challenge to balance their mechanical performance and thermal ***,we investigate m...
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Mg-Zn-based alloys have been widely used in computer,communication,and consumer(3C)products due to excellent thermal ***,it is still a challenge to balance their mechanical performance and thermal ***,we investigate microstructure,mechanical performance,thermal conductivity and metal fluidity of Mg-5Zn(wt.%)alloy after Cu alloying by experimental and simulation ***,Mg-5Zn alloy consist ofα-Mg matrix and interdendritic MgZn *** the Cu content increases,however,MgZn phases disappear but intragranular Mg_(2)Cu and interdendritic MgZnCu phases appear in Mg-5Zn-Cu ***,the grain size ofα-Mg phase is refined and the volume fraction of MgZnCu phase increases as the Cu content ***,Cu addition is found to improve thermal conductivity of Mg-5Zn alloy ***,Mg-5Zn-4Cu alloy exhibits the best thermal conductivity of 124 W/(m·K),which is mainly due to the significant reduction in both solid solubility of Zn in theα-Mg matrix and lattice distortion ofα-Mg ***,a stable crystal structure of MgZnCu phase also contributes to an increased thermal conductivity based on first principles and molecular dynamics ***,Cu addition simultaneously enhances strength and ductility of Mg-5Zn *** yield strength and elongation of Mg-5Zn-6Cu alloy reach 117 MPa and 18.0%,respectively,which is a combined result of refinement,solution,second phase,and dislocation ***,combined with a phase field simulation,we found that Cu addition enhances metal fluidity of Mg-5Zn *** the one hand,Cu alloying not only delays dendrite growth but also prolongs solidification *** the other hand,MgZnCu phase stabilizes the dendrite growth of theα-Mg phases by reducing energy consumption during solidification of liquid *** work demonstrates that Cu alloying is an ideal strategy for synergistically improving the thermal conductivity,mechanical performance and metal fluidi
The practical application of lithium–sulfur(Li–S)batteries is inhibited by the shuttle effect of lithium polysulfides(LiPSs)and slow polysulfide redox kinetics on the S cathode as well as the uncontrollable growth o...
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The practical application of lithium–sulfur(Li–S)batteries is inhibited by the shuttle effect of lithium polysulfides(LiPSs)and slow polysulfide redox kinetics on the S cathode as well as the uncontrollable growth of dendrites on the Li metal ***,both cathode and anode sides must be considered when modifying LiS ***,two-dimensional(2D)ultrathin CoSe_(2)nanobelts are in situ grown on 2D N-doped MXene nanosheets(CoSe_(2)@N-MXene)via one-step solvothermal process for the first *** to its unique 2D/2D structure,CoSe_(2)@N-MXene can be processed to crumpled nanosheets by freeze-drying and flexible and freestanding films by vacuum *** crumpled CoSe_(2)@NMXene nanosheets with abundant active sites and inner spaces can act as S hosts to accelerate polysulfide redox kinetics and suppress the shuttle effect of LiPSs owing to their strong adsorption ability and catalytic conversion effect with ***,the CoSe_(2)@N-MXene film(CoSe_(2)@NMF)can act as a current collector to promote uniform Li deposition because it contains lithiophilic CoSe_(2)and N *** the systematic effect of CoSe_(2)@N-MXene on S cathode and Li metal anode,the electrochemical and safety performance of Li–S batteries are ***_(2)@NMF also shows excellent storage performances in flexible energy storage devices.
In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were *** showed that eutectic Si underwent three stages dur...
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In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were *** showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and *** the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then *** with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical *** coarsening of microstructure was the main reason for the deterioration of mechanical *** Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the *** Al_(11)La_(3) with secondary precipitation occurred in the La-rich *** addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature *** the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 *** high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.
Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient ***,precipitates generally reduce the localized corrosion resistance in aggressive solution *** solve this problem,a...
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Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient ***,precipitates generally reduce the localized corrosion resistance in aggressive solution *** solve this problem,a strategy of introducing nano-sized L12 precipitates in CoCrFeNiAlTi HEAs has been proposed in this *** demonstrate the pitting corrosion potential can be elevated from 258 mVSCE to 603 mVSCE by increasing the precipitate content to 38 wt.％.Such an improvement in localized corrosion resistance can be attributed to two ***,L1 2 precipitates tend to be dissolved during the corrosion process,which promotes the heterogeneous nucleation of pro-tective Cr2O3 due to the rapid deposition of oxides/hydroxides of Al/Ti,and improves the passive film stability due to the Cr-rich FCC ***,the dissolution kinetic inside the pits can be suppressed on account of the enrichment of Cr element in the FCC matrix,thus inhibiting the pitting *** summary,the current work not only reveals the mechanisms of the nano-sized L12 precipitates upon the corrosion behavior,but also provides a strategy for designing corrosion-resistant HEA.
Heterostructures and the introduction of heterogeneous elements have been regarded as effective strategies to promote electrochemical performance. Herein, sulfur species are introduced by a simple hydrothermal vulcani...
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Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable ***,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanopar...
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Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable ***,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 *** well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 *** novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution *** 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 ***,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 ***,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 *** 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.
The long-lasting expectation"the hotter the engine,the better"calls for the development of high-temperature metallic *** the high specific strengths of titanium alloys are compelling for such applications,th...
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The long-lasting expectation"the hotter the engine,the better"calls for the development of high-temperature metallic *** the high specific strengths of titanium alloys are compelling for such applications,their deleterious softening beyond 600 ℃ imposes serious *** has been known for decades regarding the phase metallurgy for precipitation strengthening design in titanium al-loys,however,the other facile strength promotion mechanism,dispersion strengthening,remains compar-atively less-explored and *** present research concerns the multi-scale dispersion strength-ening in titanium alloys,with mechanistic emphases on the critical plasticity micro-events that affect strength *** to the simultaneous introduction of intragranular dispersoids and intergran-ular reinforcers,the current titanium alloys present superior engineering tensile strength of 519 MPa at 700 ℃.Throughout the examined 25-800 ℃ temperature range,noticeable softening induced by the ther-mal activation occurs above 600 ℃,accompanied by evident strength *** temperature-dependence transition of dominated softening mechanisms from dynamic recovery to dynamic recrystallization has been clarified by theoretical ***,the strengthening effect of multi-scale architec-tures is underpinned as the enhanced dislocation strengthening owing to the introduction of thermally-stable heterointerfaces,which could generically guide the design of similar heat-resistant titanium alloys.
Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium ***,the poor chemical stability and compatibility with lithium...
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Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium ***,the poor chemical stability and compatibility with lithium metal limit their ***,Li_(5.4)PS_(4.4)Cl1.4I0.2solid electrolyte with high ionic conductivity of 11.49 m S ccm^(-1)and improved chemical stability is synthesized by iodine *** ultra-thin Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane with thickness of 10μm can be obtained by wet coating process,exhibiting a high ionic conductivity of 2.09 mS ccm^(-1)and low areal resistance of 1.17Ωcm^(-2).Moreover,iodine doping could in-situ form LiI at the lithium/electrolyte interface and improve the critical current density of Li_(5.4)PS_(4.4)Cl_(1.6)from 0.8 to 1.35 mA cm^(-2).The resultant LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)/Li battery shows excellent cycling stability at 1 C,with a reversible specific capacity of 110.1 mA h g^(-1)and a retention of 80.5% after 1000 *** addition,the assembled LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane/Li pouch cell delivers an initial discharge capacity of 110.4 mA h g^(-1)and 80.5% capacity retention after 100 cycles.
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