Exciting lattice oxygen of nickel–iron bi-metal alkoxide for efficient electrochemical oxygen evolution reaction

High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.

Cu-Co bi-metal catalyst prepared by perovskite CuO/LaCoO_3 used for higher alcohol synthesis from syngas

Cu-Co bi-metal catalysts derived from CuO/LaCoO3 perovskite structure were prepared by one-step citrate complexing method, and the structure evolution reaction from CuO/LaCoO3 to Cu-Co2C/La202CO3 under 1-12 pretreatment was investigated by techniques of XRD, TPR and TEM. The results suggest that a much higher dispersion of copper significantly enhanced the reduction of cobalt, and a stronger interaction between copper and cobalt ions in LaCoO3 particles led to the formation of bi-metallic Cu-Co particles in the reduced catalysts and the enrichment of Co on the surface of bimetallic particles. The prepared catalysts were highly active and selective for the alcohol synthesis from syngas due to the presence of copper-modified C02C species.

Process optimization,microstructures and mechanical/thermal properties of Cu/Invar bi-metal matrix composites fabricated by spark plasma sintering

An orthogonal experiment scheme was designed to investigate the effects of the Cu content,compaction pressure,and sintering temperature on the microstructures and mechanical and thermal properties of(30−50)wt.%Cu/Invar bi-metal matrix composites fabricated via spark plasma sintering(SPS).The results indicated that as the Cu content increased from 30 to 50 wt.%,a continuous Cu network gradually appeared,and the density,thermal conductivity(TC)and coefficient of thermal expansion of the composites noticeably increased,but the tensile strength decreased.The increase in the sintering temperature promoted the Cu/Invar interface diffusion,leading to a reduction in the TC but an enhancement in the tensile strength of the composites.The compaction pressure comprehensively affected the thermal properties of the composites.The 50wt.%Cu/Invar composite sintered at 700℃ and 60 MPa had the highest TC(90.7 W/(m·K)),which was significantly higher than the TCs obtained for most of the previously reported Cu/Invar composites.

Perovskite LaFeO_3 supported bi-metal catalyst for syngas methanation

LaFeO3 perovskite supported Ni and Ni-Fe catalysts were prepared and applied to methanation reaction of syngas. Two preparation methods were employed. One was one-step citrate complexing method, and the other was a two step method using citrate complexing method to produce LaFeO3 and followed by loading nickel oxide on it with impregnation. The structure evolution of the sample as prepared was investigated by XRD, TPR and TEM techniques. For the former, the chemical composites of the calcined sample are NiO-Fe2O3/LaFe1-xNixO3. After reduction and reaction of CO methanation, its composites convert to Fe-Ni@Ni/LaFeO3-La2O2CO3, in which Fe-Ni@Ni is metal particles in nano-size composed of nickel core and Fe-Ni alloy shell. For the latter, the chemical composites of the calcined sample are NiO/LaFeO3; and after reduction and reaction of CO methanation, its chemical composites change to Ni/LaFeO3. Ni/LaFeO3 catalyst is a little more active, while Fe-Ni@Ni/LaFeO3-La2O2CO3 is much more stable and shows very good resistance to carbon deposition. In this work it is aimed to show that the structure and composites of the catalysts can be tailored using perovskite-type oxide as precursor with different preparing method or preparing condition. Therefore, it is a promising route to prepare supported bi-metal catalysts in nano-size for a lot of metals with desired catalytic performances.

Observation of interface of two kinds of bi-metal composite parts prepared by thixo-forging

Two kinds of bi-metal composite parts （Sn-15%Pb and Pb-22%Sn bi-metal system, and Al-7%Si and SiCp/6061 MMC bi-metal system） were prepared by the strain-induced melt activated thixo-forging. The interfaces of the bi-metal composites were observed by OM and SEM. The observations show that the semisolid metals keep independence during thixo-forging. The solid phases in the semisolid slurries maintain their original morphologies after thixo-forging. The liquid phases near the interface mix together and form a thin layer. The interfaces are bonded firmly with the metallurgical bonding. No oxide layers are found at the interfaces. Strengths of the interfaces were investigated by the micro-hardness test. The experimental results show that the composite interfaces have high strength. However, the agglomerated enhancing particles cause fine defect on the interface of the Al-7%Si and SiCr/6061 MMC bi-metal composite.

Impacts of zinc layer and pouring method on interface performance for Al-22Si/ZL104 bi-metal

Bi-metal material consisting of spray-formed Al-22Si and ZL104 is a suitable candidate for applications in internal combustion engines. This research investigated the effects of surface treatment and appropriate gating system on the microstructures and mechanical properties in evaluating the optimal strategy for producing high quality bi-metal materials. The bi-metal materials were prepared using ZL104 gravity casting by different pouring types around the spray-formed AI-22Si with varied surface treatments. The wettability between AI-22Si and ZL104 was significantly improved when Zn coating was used to remove the natural oxide layer. This research also obtained the improved interfacial microstructures and interracial bonding strength for materials when applying the appropriate pouring method. The hardness profiles of AI-22Si/ZL104 bi-metal were consistent with the observed microstructures. The average tensile strength of the bi-metal material with zinc coating is -42.3 MPa, which is much higher than that with oxide film at -10 MPa. The process presented is a promising and effective approach for developing materials in the automotive industry.

A pathway to refined stress and strain distributions in aerospace-grade Ti/Al bi-metal sheets:Synergizing theoretical insights and FEM simulations

This study introduces an innovative theoretical model critical for predicting stress and strain distributions in Ti/Al bi-metal sheet production and its subsequent deep drawing process.Grounded in extensive mechanical and geometric analysis,the model facilitates manufacturing process optimization and the production of high-quality components.Finite Element Method(FEM)simulations are integrated to examine the significant effects of die geometric parameters on metal flow dynamics and susceptibility to material stress.The model's precision is enhanced by incorporating anisotropic material properties and cohesive zone models.A rigorous experimental framework validates the model,highlighting the practical utility of optimized parameters in Ti/Al bimetal component fabrication.Additionally,uniaxial tensile tests using the Video Image Correlation-3D(VIC-3D)system provide detailed insights into material deformation,elucidating stress distribution and metal flow in composite layers.Thus,the research presents a refined methodology for the efficient production of Ti/Al bi-metal components,offering valuable knowledge transferable to various materials and processing scenarios.The findings of this work are expected to make a significant impact on material engineering and mechanical manufacturing.

弯曲载荷下双金属机械复合管内衬层屈曲失效机理

双金属机械复合管是油气田集输管线防腐控制的主要措施之一,而内衬层的失效是制约复合管工程应用的关键难题。为研究双金属机械复合管内衬层屈曲失效机理,建立弯曲载荷下复合管力学模型,研究成型压力、工作内压及复合管结构参数对内衬层失效模式的影响规律。结果表明:增加成型后的残余接触压力有助于提高内衬层的抗屈曲能力;较高的工作内压能够延缓内衬层屈曲时间,减小其褶皱幅值;成型前复合管层间初始间隙减小有利于提高内衬层抗屈曲能力;随着外基管壁厚、内衬管壁厚、复合管内径的增加,内衬管的抗屈曲能力增强。

High-rate lithium-ion battery performance of a ternary sea urchin-shaped CoNiO_(2)@NiP_(6)Mo_(18)/CNTs composites

Bimetallic oxides are attractive anode materials for lithium-ion batteries(LIBs)due to their large theoretical capacity.However,the low conductivity,short cycle life,and poor rate capability are the bottlenecks for their further applications.To overcome above issues,the basket-like polymolybdate(NiP_(6)Mo_(18))and carbon nanotubes(CNTs)were uniformly embedded on the urchin-shaped CoNiO_(2)nanospheres to yield a ternary composites CoNiO_(2)@NiP_(6)Mo_(18)/CNTs via electrostatic adsorption.The multi-level morphology of urchin spinules accelerates the diffusion rate of Li^(+);CNT improves the conductivity and enhances cycle stability of the material;and heteropoly acid contributes more redox activity centres.Thus,CoNiO_(2)@NiP_(6)Mo_(18)/CNTs as an anode of LIBs exhibits a high initial capacity(1396.7 mA h g^(−1)at 0.1 A g^(−1)),long-term cycling stability(750.2 mA h g^(−1)after 300 cycles),and rate performance(450.3 mA h g^(−1)at 2 A g^(−1)),which are superior to reported metallic oxides anode of LIBs.The density functional theory(DFT)and kinetic mechanism suggest that CoNiO_(2)@NiP_(6)Mo_(18)/CNTs delivers an outstanding pseudocapacitance and rapid Li^(+)diffusion behaviors,which is due to the rich surface area of the urchin-like CoNiO_(2)with the uniform embeddedness of NiP_(6)Mo_(18)and CNTs.This study provides a new idea for optimizing the performance of bimetallic oxides and developing high-rate lithium-ion battery composites.

Simulating the Dynamics of Bimetallic Clusters Deposited onto a Surface Using Molecular Dynamics

This paper examines the interface development between a single crystalline Ag matrix and core-shell AgnCom nanoclusters that have been deposited with energies varying between 0.25 eV and 1.5 eV per atom using computer modeling techniques. Clusters undergo deformation as a result of the slowing down;they may also become epitaxial with the substrate and maintain their core-shell structure. A detailed analysis of the effects of the cluster-surface interaction is conducted over a realistic size and energy range, and a model is created to show how clusters accumulate. It is discovered that both the silver shells and the cobalt cluster cores exhibit limited epitaxy with the substrate, and that the contact produced is only a few atomic layers thick. The effect is higher for Ag shells than for Co cores, and it is not very energy dependent.

三维多孔铜及表面修饰铋协同构筑无枝晶锂金属电极

以化学镀制备的具有微米级三维(3D)多孔结构的3D多孔铜为基底,在其表面电沉积铋修饰层,构建了3D Cu@Bi;将其作为锂金属电极集流体.孔径约5μm的3D多孔结构具有高表面积,有利于降低局部电流密度,电流密度分布更均匀,其大容纳空间可缓解体积变化和释放应力,抑制锂枝晶生长.Bi的亲锂性促进了界面动力学,降低了形核过电位,增强了锂沉积/剥离的可逆性.在3D多孔结构和铋修饰层的协同作用下,锂金属沉积容量>4 mA·h/cm^(2)时,电极表面仍保持平整、光滑;由其组装的半电池经过200次循环后,库仑效率(CE)可保持在98.5%以上;由其组装的对称电池在电流密度为0.5 mA/cm^(2),面容量为1 mA·h/cm^(2)时,可稳定循环1500 h以上,循环100次后电极表面仍光滑、无枝晶;以磷酸铁锂为正极组装的LFP||3D Cu@Bi@Li全电池在1.0C倍率下经过200次循环后,显示出132 mA·h/g的高容量和约87.2%的容量保持率.

汉长安城武库出土铠甲片与铁铤的制作工艺研究

汉长安城武库遗址出土了大批西汉铁器,其中铠甲片、金属镞出土数量丰富,种类繁多。本文系统分析了24件铠甲片与17件残镞铁铤,发现残铁铤既包括铜镞之铤,也存在铁镞之铤,且存在不同的接铸顺序;所分析的铠甲片属于铜铁复合器,与铜镞之铤均存在超薄的夹铜层结构。依据两者微观结构特征,本文进一步认为具有铜铁复合架构的铠甲片是由这些铜镞之残铤经退火、锻打制成,且铠甲片的整个加工流程应完成于武库内,因此武库除屯藏兵备的职能外,还具有铁器锻造成型、加工的功能。

锡铋合金/肉豆蔻酸制备具有金属外壳的储能木材

【目的】利用锡铋合金对肉豆蔻酸浸渍材进行热处理,在热的驱动下将锡铋合金引入木材内部,以解决木基相变储能材料面临的液体泄漏和导热性差问题。【方法】以浸渍了肉蔻豆酸的杨木为基材,通过高低温交替热处理将锡铋合金与基材结合,制备具有金属外壳的储能木材。利用扫描电镜、邵氏硬度计、万能力学试验机、导热系数仪、差式扫描量热仪对储能木材的微观形貌、端面硬度、顺纹抗压强度和热性能进行测试。【结果】在160~220℃热处理1~5 min下试样质量增长效果显著,力学性能与热性能随着热处理温度的上升与时间的延长而提升,顺纹抗压强度和端面硬度相较于未处理材分别提升了120.02%~149.59%、13.53%~46.93%,轴向、径向导热率分别提升了34.18%~165.67%、38.11%~80.70%。在190℃热处理5 min条件下锡铋合金的填充效果最佳,端面硬度、轴向、径向导热率达到最高值62.65 HD、0.5324和0.2987 W/(m·K)。木材内部肉豆蔻酸的留存率介于27.54%~63.68%之间,经过160℃热处理3 min后储能密度最高(59.38 J/cm3)。【结论】高低温交替热处理促使锡铋合金进入到木材的导管内,实现了不同程度的渗透。木材的三维孔隙结构与外层填充的锡铋合金解决了相变材料的液体泄漏及导热性差问题。制备的储能木材综合了木材、金属与相变材料的优势,具有更优异的端面硬度、顺纹抗压强度与热性能,有望应用于建筑墙体和储能地板等领域。

泡沫镍原位生长普鲁士蓝类似物构筑镍铁双金属氧化物催化剂的氧析出反应性能研究

开发高性能、低成本的氧析出反应(OER)催化剂对促进电解水制氢降低电耗、提高经济性具有重要意义。以导电泡沫镍为基底,采用冰水浴法原位生长镍铁普鲁士蓝类似物,氧化制备了镍铁双金属氧化物催化剂。分别采用X射线衍射、扫描电镜、高分辨率透射电镜和X射线光电子能谱方法对催化剂的物相组成、微观形貌和表面化学状态进行了表征,并采用电化学测试表征了催化剂的OER催化性能。结果表明,当氧化温度为200℃、氧化时间为2 h时,制备的催化剂中镍铁双金属氧化物高度分散在泡沫镍基底上,纳米颗粒最小,平均粒径为71 nm,可暴露的催化反应活性位点多,表现出最优的OER催化性能。该催化剂在1.0 mol/L的KOH电解液中,电流密度为10 mA/cm^(2)时,过电位仅为272 mV,并在电流密度为100 mA/cm^(2)时稳定运行了40 h,表现出优异的OER电化学稳定性。

NiAl催化剂催化5-羟甲基糠醛加氢制备2,5-二羟甲基四氢呋喃

[目的] 5-羟甲基糠醛(HMF)是最重要的生物质基平台化学品之一,可以通过催化加氢途径制备许多高附加值化学品.本文为设计在更加温和的条件下达到高效催化HMF加氢的非贵金属催化剂进行了一系列研究.[方法]通过尿素共沉淀法制备了一种NiAl催化剂,考察了NiAl催化剂催化HMF加氢制备2,5-二羟甲基四氢呋喃(BHMTHF)的性能,并利用X射线衍射(XRD)、氢气程序升温还原(H_(2)-TPR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氨气程序升温脱附(NH_(3)-TPD)、X射线光电子能谱(XPS)等表征方法系统地研究了不同Ni/Al比、不同煅烧温度和还原温度对催化剂理化性质的影响.[结果] Ni和Al的投料原子比为3∶1,在350℃下煅烧、650℃下还原制备的催化剂Ni_(3)Al-350-650在100℃、氢气压力2.5 MPa的条件下反应1 h,HMF的转化率和BHMTHF产率分别高达99.5%和87.5%.过高的Ni/Al比制备的催化剂比表面积较小,导致暴露的活性位点较少从而降低了催化活性,通过煅烧温度可以调节NiAl催化剂的可还原性.[结论]本研究实现了在温和条件下HMF的高效催化加氢转化.该结果可为用于HMF定向转化的非贵金属催化剂的设计提供参考.

铋基金属有机框架材料的合成及光催化研究进展

铋基金属有机框架(Bi-MOF)材料综合铋基光催化剂和金属有机框架(MOFs)材料的优点,具有极大的应用潜力。本文介绍了Bi-MOF材料常见的制备方法,包括水热/溶剂热法、微波法、共沉淀法、机械化学法和高温退火法等;梳理了Bi-MOF材料作为光催化剂在处理废水、固氮、制氢、还原CO_(2)等方面的最新研究进展,分析了现阶段Bi-MOF材料在光催化方面存在的问题,对Bi-MOF材料在光催化领域的发展方向进行了展望。

含能金属有机框架[Ag_(2)(HOBTT)]_(n)的制备与性能表征

以4,5-二(1-羟基-四唑)-1,2,3-三唑(H 3OBTT)为配体,Ag(Ⅰ)作为金属中心,采用溶剂热法合成了一种新的含能金属有机框架材料[Ag_(2)(HOBTT)]_(n);通过单晶X射线衍射(SXRD)、粉末X射线衍射(PXRD)、元素分析(EA)和红外光谱(IR)表征了其结构;采用差示扫描量热仪(DSC)和热重分析仪(TG)研究了其热稳定性,基于Kissinger法获得了非等温热分解动力学参数;通过撞击感度仪、摩擦感度仪考察了[Ag_(2)(HOBTT)]_(n)的机械感度;根据GGA-PBE泛函得到[Ag_(2)(HOBTT)]_(n)的爆炸热,并结合Kamlet-Jacobs方程计算得到爆速和爆压。结果表明,[Ag_(2)(HOBTT)]_(n)为三维框架结构,结构中不含溶剂分子,晶体属于斜方晶系、Fddd空间群,晶体密度为3.309 g/cm^(3),起始热分解温度为586.6 K,热分解动力学参数分别为E_(a)=255.18 kJ/mol、ln(A/s^(-1))=43.30,撞击感度IS>40 J、摩擦感度FS=108 N,爆速为7.68 km/s,爆压为35.08 GPa。表明[Ag_(2)(HOBTT)]_(n)热稳定性好,机械感度适中,爆轰性能优异,是一种具有应用前景的含能材料。

基于多区多求解器的金属-介质复合目标电磁散射特性分析

在导弹类金属-介质复合目标电磁散射特性求解过程中,采用常规迭代求解方法存在难以收敛以及内迭代边界积分区域重复求解的问题。针对该问题,在传统有限元边界积分区域分解法(finite element boundary integral domain decomposition method,FE-BI-DDM)的基础上,采用了更为灵活的多区多求解器的方法(multi domain multi solver method,MDMSM)。该方法对导弹类金属-介质复合目标中难以收敛的金属区域,使用快速直接求逆的方法求解,由于可以使用独立的网格模型进行电磁建模,避免了内迭代部分的模型重复建立过程,从而大幅减少了整体模型求解时间。实验结果表明:所提方法可以在相同计算精度的条件下,以不过多增加内存空间为前提,大幅缩短了导弹类目标的金属-介质复合模型的电磁求解时间。该方法为开展导弹类目标特性分析提供了一条可行的技术途径。

Recent update on electrochemical CO_(2)reduction catalyzed by metal sulfide materials

Seeking and developing efficient CO_(2)reduction reaction(CO_(2)RR)electrocatalysts is a hot topic in this era of global warming.Among material candidates for sustainable and cost-effective applications,metal sulfides have attracted attention as promising nature-inspired materials due to multiple adsorption sites which are enhanced by the covalent character of sulfur.This article summarizes the current status regarding the utilization and development of metal sulfide materials as CO_(2)RR electrocatalysts.First,the research background and basic principles of electrochemical CO_(2)RR are introduced.Next,an overview of the main obstacles to developing efficient CO_(2)RR electrocatalysts is presented.The section is followed by a summary of the empirical evidence supporting the application of metal sulfides as CO_(2)RR electrocatalysts beside nature-inspired motivation.The summary of synthesis methods of various metal sulfides is also presented.Furthermore,the paper also highlights the recent works on metal sulfide as efficient CO_(2)RR including the undertaking strategy on the activity enhancement,and finally,discusses the challenges and prospect of metal sulfides-based CO_(2)RR electrocatalysts.Despite recent efforts,metal sulfides remain relatively unexplored as materials for CO_(2)RR electrocatalytic applications.Therefore,this review aims to stimulate novel ideas and research for improved catalyst designs and functionality.

C_(6)^(+)正构烷烃芳构化的研究进展

通过烷烃芳构化可将催化裂化汽油深度脱硫工艺和煤制油工艺中产生的大量低辛烷值饱和直链烷烃转化成芳烃,从而提升油品质量和芳烃产能,是制备芳烃的重要非石油路线,具有显著的社会经济价值。其中,C_(2)-C_5轻烃芳构化技术相对成熟,已进入到工业应用阶段;而针对C_(6)^(+)直链烷烃芳构化,由于反应过程复杂、多种基元反应相互竞争,导致芳烃收率偏低、催化剂易结焦失活。为此,本工作综述了近年来有关C_(6)^(+)正构烷烃芳构化的研究进展,重点讨论了C_(6)^(+)直链烷烃芳构化的反应机理以及单功能及双功能催化体系中金属位点分散度、电子状态及载体的酸性、形貌和孔道结构等对反应性能的影响。