Superior multiphase interfaces in AgCuTe-based composite with significantly enhanced thermoelectric properties

It is common sense that a phase interface(or grain boundary)could be used to scatter phonons in thermoelectric(TE)materials,resulting in low thermal conductivity(k).However,a large number of impurity phases are always so harmful to the transport of carriers that poor TE performance is obtained.Here,we demonstrate that numerous superior multiphase(AgCuTe,Ag_(−2)Te,copper telluride(Cu_(2)Te and Cu_(2−x)Te),and nickel telluride(NiTe))interfaces with simultaneous strong phonon scattering and weak electron scattering could be realized in AgCuTe-based TE materials.Owing to the similar chemical bonds in these phases,the depletion region at phase interfaces,which acts as carrier scattering centers,could be ignored.Therefore,the power factor(PF)is obviously enhanced from~609 to~832μW·m^(−1)·K^(−2),and k is simultaneously decreased from~0.52 to~0.43 W·m^(−1)·K^(−1) at 636 K.Finally,a peak figure of merit(zT)of~1.23 at 636 K and an average zT(zTavg)of~1.12 in the temperature range of 523–623 K are achieved,which are one of the best values among the AgCuTe-based TE materials.This study could provide new guidance to enhance the performance by designing superior multiphase interfaces in the TE materials.

In-situ electro-deposition synthesis of MnO_(x)-NiCo_(2)O_(4) monolithic catalyst with rich phase interfaces

A hierarchically structured MnO_(x)-NiCo_(2)O_(4) monolithic catalyst with rich phase interfaces was designed by a simple,eco-friendly and time-saving in-situ electro-deposition method.The abundance of active oxygen species due to this rich phase interfaces contributed to the excellent benzene combustion performance of MnO_(x)-NiCo_(2)O_(4)-2:2 sample,oxidizing about 90% of benzene(T_(90)) at 198℃ under 12000 h^(-1) gaseous hourly space velocity.This work shed new light on the design of excellent monolithic catalysts,which might pave the way for the industrialization of benzene combustion.

Design of phase interface and defect in niobium-nickel oxide for ultrafast Li-ion storage

Niobium pentoxide(Nb2O5)has attracted much attention in lithium batteries due to its advantages of high operating voltage,large theoretical capacity,environmental friendliness and cost-effectiveness.However,the intrinsic poor electrical conductivity,sluggish kinetics,and large volume changes hinder its electrochemical performance at high power density,making it away from the requirements for practical applications.In this research work,we regulate the electron transport of niobium-nickel oxide(NiNbO)anode material with enhanced structural stability at high power density by constructing the two-phase boundaries between niobium pentoxide(Nb2O5)and nickel niobate(NiNb2O6)through simple solid phase reaction.In addition,the presence of lattice defects in NiNbO-F further speeds up the transport of Li+and promotes the electrochemical reaction kinetics more effectively.The two-phase boundaries and defect modulated anode material displays high Li+diffusion coefficient of 1.63×10^(−10) cm^(2) s^(−1),pretty high initial discharge capacity of 222.8 mAh g^(−1) at 1 C,extraordinary high rate performance(66.7 mAh g^(−1))at an ultrahigh rate(100 C)and ultra-long cycling stability under high rate of 25 C(83.4 mAh g^(−1) after 2000 cycles)with only 0.016%attenuation per cycle.These results demonstrate an effective approach for developing electrode materials that greatly improve rate performance and durability.

Customizing the microenvironment of CO_(2) electrocatalysis via three‐phase interface engineering

Converting CO_(2) into high‐value fuels and chemicals by renewable‐electricitypowered electrochemical CO_(2) reduction reaction(CRR)is a viable approach toward carbon‐emissions‐neutral processes.Unlike the thermocatalytic hydrogenation of CO_(2) at the solid‐gas interface,the CRR takes place at the three‐phase gas/solid/liquid interface near the electrode surface in aqueous solution,which leads to major challenges including the limited mass diffusion of CO_(2) reactant,competitive hydrogen evolution reaction,and poor product selectivity.Here we critically examine the various methods of surface and interface engineering of the electrocatalysts to optimize the microenvironment for CRR,which can address the above issues.The effective modification strategies for the gas transport,electrolyte composition,controlling intermediate states,and catalyst engineering are discussed.The key emphasis is made on the diverse atomic‐precision modifications to increase the local CO_(2) concentration,lower the energy barriers for CO_(2) activation,decrease the H2O coverage,and stabilize intermediates to effectively control the catalytic activity and selectivity.The perspectives on the challenges and outlook for the future applications of three‐phase interface engineering for CRR and other gasinvolving electrocatalytic reactions conclude the article.

Toward developing Ti alloys with high fatigue crack growth resistance by additive manufacturing

Fatigue crack growth behaviors were investigated by three-point bending tests for TA19 alloy fabricated by laser metal deposition and four kinds of heat-treated samples.The crack growth resistance of the TA19 samples in the near-threshold regime and Paris regime was evaluated through the experimental characterization and theoretical analysis of the interaction between fatigue crack andα/βphase inter-face,columnar prior-βgrain boundary and colony boundary.The results show that in the near-threshold regime,the fatigue crack propagation threshold and resistance increase with the increase of widths of lamellarαp phases and colonies,and the decrease of the number ofαlaths with an angle(ϕ)relative to the applied stress direction ranging from 75°to 90°.In the Paris regime,the fatigue cracking path can be deflected at colony boundaries or columnar prior-βgrain boundaries.The larger the deflection angle,the more tortuous the cracking path and the lower the fatigue crack growth rate.The angle(γ)of the columnar prior-βgrain growth direction relative to the build direction affects not onlyϕof differentαvariants,but also the fatigue cracking path deflection angle(θij)at columnar prior-βgrain boundaries.An optimal combination ofγ=0°-15°-0°-15°for several adjacent columnar prior-βgrains is derived from the theoretical analysis,and that can effectively avoidϕbeing in the range from 75°to 90°and makeθij as large as possible.Such findings provide a guide for the selection of scanning strategies and process parameters to additively manufacture Ti alloys with high fatigue damage tolerance.

Water-in-Water Emulsions,Ultralow Interfacial Tension,and Biolubrication

A water-in-water(W/W)emulsion consists of droplets formed by the spontaneous liquid-liquid separation of two immiscible aqueous phases.The inherent properties of the W/W interfaces,low or ultralowinterfacial tension(γ_(W/W)=1-1000μN/m)and a large thickness of several nanometers,beget the poor inherent stability of emulsions.Herein,we report a nanofibril emulsifier having Schiff base reactivity to generate a W/W emulsion.The W/W emulsion has superior stability(stable>6 months)because collagen nanofibrils,acting as a stabilizer of W/W emulsions,can simultaneously satisfy the requirements of sizeandoverall coverage ratio of the phase interfaces.W/Wemulsions having γ_(W/W)∼10μN/m were used as synthetic synovial fluids,showing superior lubrication performance with a coefficient of friction in the range of 0.003-0.011,which has been demonstrated to be suitable for joint lubrication.An intraarticular injection assessment further confirmed this protective effect on articular cartilage in vivo.Our study reveals the mechanism of emulsion stabilization and opens up the possibility of osteoarthritis(OA)treatment using the biolubrication effects of W/W emulsions for lubricated artificial implant surfaces.