High entropy alloy electrocatalysts

Compared to traditional pure metals or alloys based on just one principal element,high entropy alloys(HEAs)exhibit notable structural and physical characteristics,drawing significant attention.While significant advancements have been made in the synthesis and utilization of HEAs,there is a lack of comprehensive understanding and systematic approach towards the rational design of electrocatalysts.This review begins by introducing the fundamental principles and impacts of HEAs,followed by an overview of traditional and emerging synthesis techniques;in particular,we categorize and critically analyze approaches.Subsequently,a detailed examination of the advancements and comparative performance of HEAs in specific electrocatalytic reactions is presented.The paper concludes by outlining the current challenges and opportunities associated with HEAs catalysts,along with offering personal insights on potential future developments.

中空结构材料专辑

中空结构材料是一类具有内部空腔、壳壁的形貌组成多变的先进功能材料.从细胞到宇宙,中空结构在自然界中无处不在,发挥着独特且非常重要的作用,也为材料的设计带来了灵感.中空结构材料因具有密度低、比表面积大、负载能力高及壳壁形貌组成数目可控等特性,使其在能量转换与存储、催化和生物医药等领域获得广泛应用.

Boosting Lean Electrolyte Lithium-Sulfur Battery Performance with Transition Metals: A Comprehensive Review

Lithium–sulfur(Li–S) batteries have received widespread attention, and lean electrolyte Li–S batteries have attracted additional interest because of their higher energy densities. This review systematically analyzes the effect of the electrolyte-to-sulfur(E/S) ratios on battery energy density and the challenges for sulfur reduction reactions(SRR) under lean electrolyte conditions. Accordingly, we review the use of various polar transition metal sulfur hosts as corresponding solutions to facilitate SRR kinetics at low E/S ratios(< 10 μL mg~(-1)), and the strengths and limitations of different transition metal compounds are presented and discussed from a fundamental perspective. Subsequently, three promising strategies for sulfur hosts that act as anchors and catalysts are proposed to boost lean electrolyte Li–S battery performance. Finally, an outlook is provided to guide future research on high energy density Li–S batteries.

Phase formation and thermoelectric properties of Zn_(1+x)Sb binary system

The phase formation and thermoelectric(TE)properties in the central region of the Zn−Sb phase diagram were analyzed through synthesizing a series of Zn_(1+x)Sb(x=0,0.05,0.1,0.15,0.25,0.3)materials by reacting Zn and Sb powders below the solidus line of the Zn−Sb binary phase diagram followed by furnace cooling.In this process,the nonstoichiometric powder blend crystallized in a combination of ZnSb andβ-Zn4Sb3 phases.Then,the materials were ground and hot pressed to form dense ZnSb/β-Zn4Sb3 composites.No traces of Sb and Zn elements or other phases were revealed by X-ray diffraction,high resolution transmission electron microscopy and electron energy loss spectroscopy analyses.The thermoelectric properties of all materials could be rationalized as a combination of the thermoelectric behavior of ZnSb andβ-Zn4Sb3 phases,which were dominated by the main phase in each sample.Zn1.3Sb composite exhibited the best thermoelectric performance.It was also found that Ge doping substantially increased the Seebeck coefficient of Zn1.3Sb and led to significantly higher power factor,up to 1.51 mW·m−1·K−2 at 540 K.Overall,an exceptional and stable TE figure of merit(ZT)of 1.17 at 650 K was obtained for Zn1.28Ge0.02Sb.

Modulation doping of p-type Cu_(12)Sb_(4)S_(13)toward improving thermoelectric performance

The commercial viability of thermoelectric(TE)devices relies heavily on two factors:cost reduction and efficiency enhancement.In this study,we first produce p-type Cu_(12)Sb_(4)S_(16-x)(x=0,3,4)using a low-temperature bottom-up approach and demonstrate Cu_(12)Sb_(4)S_(13)to show the best TE performance among the three tested compositions.Subsequently,the TE energy conversion efficiency of Cu_(12)Sb_(4)S_(13)is further enhanced by optimizing its electronic band structure through the incorporation of small amounts of tel-lurium.At an optimal Te content of 5 mol%,more than a twofold increase in the TE figure of merit(zT)is obtained.To gain insight into the mechanism of improvement on the transport properties of the mate-rial,we compare the interphase transport mechanism by incorporating nanodomains of different metals(Ag and Cu)into the Cu_(12)Sb_(4)S_(13)matrix.The improved electrical conductivity obtained with Cu_(12)Sb_(4)S_(13)-Te nanocomposites is attributed to a charge flooding of the Cu_(12)Sb_(4)S_(13)surface.In contrast,excessive down-ward band-bending at the interphases of Ag/Cu metal-semiconductor drastically reduces the electrical conductivity.Besides,a weighted mobility(μw)analysis shows a dominant thermal activation of carri-ers in Cu_(12)Sb_(4)S_(13)-Te nanocomposites.In this material,a strong decrease in lattice thermal conductivity is also found,which is associated with a phonon-carrier scattering mechanism.Our work shows the impor-tance of proper band-engineering in TE nanocomposites to decouple electrical and thermal transport to enhance TE performance,and the efficacy ofμw for electrical and thermal transport analysis.

Unraveling the role of iron on Ni-Fe alloy nanoparticles during the electrocatalytic ethanol-to-acetate process

The anodic electrooxidation of ethanol to value-added acetate is an excellent example of replacing the oxygen evolution reaction to promote the cathodic hydrogen evolution reaction and save energy.Herein,we present a colloidal strategy to produce Ni-Fe bimetallic alloy nanoparticles(NPs)as efficient electrocatalysts for the electrooxidation of ethanol in alkaline media.Ni-Fe alloy NPs deliver a current density of 100 mA·cm^(-2) in a 1.0 M KOH solution containing 1.0 M ethanol merely at 1.5 V vs.reversible hydrogen electrode(RHE),well above the performance of other electrocatalysts in a similar system.Within continuous 10 h testing at this external potential,this electrode is able to produce an average of 0.49 mmol·cm^(-2)·h^(-1) of acetate with an ethanol-to-acetate Faradaic efficiency of 80%.A series of spectroscopy techniques are used to probe the electrocatalytic process and analyze the electrolyte.Additionally,density functional theory(DFT)calculations demonstrate that the iron in the alloy NPs significantly enhances the electroconductivity and electron transfer,shifts the rate-limiting step,and lowers the energy barrier during the ethanol-to-acetate reaction pathway.

Surface strain-enhanced MoS_(2)as a high-performance cathode catalyst for lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)are one of the main candidates for the next generation of energy storage systems.To improve the performance of LSBs,we herein propose the use of strained MoS_(2)(s-MoS_(2))as a catalytically active sulfur host.The introduction of strain in the MoS_(2)surface,which alters its atomic positions and expands the S-Mo-S angle,shifts the d-band center closer to the Fermi level and provides the surface with abundant and highly active catalytic sites;these enhance the catalyst's ability to adsorb lithium polysulfides(LiPS),accelerating its catalytic conversion and promoting lithium-ion transferability.Strain is generated through the synthesis of core-shell nanoparticles,using different metal sulfides as strain-inducing cores.s-MoS_(2)nanoparticles are supported on carbon nanofibers(CNF/s-MoS_(2)),and the resulting electrodes are characterized by capacities of 1290 and 657 mAh g−1 at 0.2 and 5 C,respectively,with a 0.05%capacity decay rate per cycle at 8 C during 700 cycles.Overall,this work not only provides an ingenious and effective strategy to regulate LiPS adsorption and conversion through strain engineering,but also indicates a path toward the application of strain engineering in other energy storage and conversion fields.

PdMoSb trimetallene as high-performance alcohol oxidation electrocatalyst

Metallenes are an emerging class of two-dimensional(2D)material with outstanding potential in electrocatalysis.Herein,we present a new PdMoSb trimetallene produced by a facile wet-chemistry procedure and tested for the alcohol oxidation reaction.PdMoSb shows an extremely high Pd utilization and superior performance toward ethanol,methanol,and glycerol electro-oxidation compared with PdMo and commercial Pd/C catalysts.Experimental results and density functional theory calculations reveal that the enhanced activity relies not only on the high surface area that characterizes the ultrathin 2D metallene structure,but also on the particular electronic configuration of Sb.Sb facilitates OH−adsorption in the reactive-intermediate pathway and strongly enhances the CO tolerance in the poisoning-intermediate pathway for alcohol oxidation.The excellent alcohol oxidation performance of PdMoSb trimetallene demonstrates the high potential of multimetallenes in the field of electrocatalysis.

Stabilizing highly active atomically dispersed NiN_(4)Cl sites by Cl-doping for CO_(2)electroreduction

Nickel-nitrogen-carbon single-atom catalysts have attracted widespread interest for CO_(2)electroreduction but they suffer from poor stability.Herein,we report on the preparation of Cl-and N-doped porous carbon nanosheets with atomically dispersed NiN_(4)Cl active sites(NiN_(4)Cl-ClNC)through a molten-salt-assisted pyrolysis strategy.The optimized NiN_(4)Cl-ClNC catalyst delivers exceptional CO_(2)conversion activity with outstanding stability for over 220 h at−0.7 V versus RHE and a high CO Faradaic efficiency of 98.7%at a CO partial current density of 12.4 mA cm^(−2).Moreover,NiN_(4)Cl-ClNC displays a remarkable CO partial current density of approximately 349.4 mA cm^(−2)in flow-cell,meeting the requirements of industrial applications.Operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy and density functional theory calculations are used to understand the outstanding activity and stability.Results reveal that the introduced axial Ni-Cl bond on the Ni center and Cl─C bond on the carbon support synergetically induce electronic delocalization,which not only stabilizes Ni against leaching but also facilitates the formation of the COOH*intermediate that is found to be the rate-determining step.