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Investigation of the preparation methodologies of Pd-Cu single atom alloy catalysts for selective hydrogenation

Xinxiang Cao,Arash Mirjalili,James Wheeler,Wentao Xie,Ben W.-L. Jang

《化学科学与工程前沿（英文）》 2015年 第9卷 第4期   页码 442-449 doi: 10.1007/s11705-015-1547-x

摘要： Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) and H chemisorption results confirmed that Pd-Cu single-atom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.

关键词： H2 pulse chemisorption     palladium-copper bimetallic catalyst     single atom alloy     acetylene hydrogenation     HAADF-STEM    

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Promising approach for preparing metallic single-atom catalysts: electrochemical deposition

《能源前沿（英文）》 2022年 第16卷 第4期   页码 537-541 doi: 10.1007/s11708-022-0837-5

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Oxygen reduction electrocatalysis: From conventional to single-atomic platinum-based catalysts for proton

《能源前沿（英文）》 doi: 10.1007/s11708-023-0907-3

摘要： Platinum (Pt)-based materials are still the most efficient and practical catalysts to drive the sluggish kinetics of cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, their catalysis and stability performance still need to be further improved in terms of corrosion of both carbon support and Pt catalyst particles as well as Pt loading reduction. Based on the developed synthetic strategies of alloying/nanostructuring Pt particles and modifying/innovating supports in developing conventional Pt-based catalysts, Pt single-atom catalysts (Pt SACs) as the recently burgeoning hot materials with a potential to achieve the maximum utilization of Pt are comprehensively reviewed in this paper. The design thoughts and synthesis of various isolated, alloyed, and nanoparticle-contained Pt SACs are summarized. The single-atomic Pt coordinating with non-metals and alloying with metals as well as the metal-support interactions of Pt single-atoms with carbon/non-carbon supports are emphasized in terms of the ORR activity and stability of the catalysts. To advance further research and development of Pt SACs for viable implementation in PEMFCs, various technical challenges and several potential research directions are outlined.

关键词： oxygen reduction electrocatalysis     Pt single-atom catalysts     conventional Pt-based catalysts     design thoughts and synthesis     metal-support interactions    

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Real atom economy and its application for evaluation the green degree of a process

Weihan WANG, Jing Lü, Li ZHANG, Zhenhua LI

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 349-354 doi: 10.1007/s11705-010-1030-7

摘要： Green chemistry has attracted more attention in the past century. Among the 12 principles of green chemistry, only atom economy and E factor can be expressed quantitatively to depict the impact of a chemical process to environment. Atom economy was thought better than the traditional yield for evaluating the atom efficiency of raw materials. But it is not enough to reflect the conversion degree of raw material. In this paper, we proposed the concept of real atom economy (RAE) as a metric. RAE could combine the above two factors together to better express the green degree of a process. We further suggested an equation to correlate E factor with RAE. The concept of RAE is proved to be helpful for estimating an environmentally benign process.

关键词： green chemistry     real atom economy     E factor     atom economy     yield    

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Spin polarization strategy to deploy proton resource over atomic-level metal sites for highly selective CO electrolysis

《化学科学与工程前沿（英文）》 2022年 第16卷 第12期   页码 1772-1781 doi: 10.1007/s11705-022-2197-4

摘要： Unlocking of the extremely inert C=O bond during electrochemical CO2 reduction demands subtle regulation on a key “resource”, protons, necessary for intermediate conversion but also readily trapped in water splitting, which is still challenging for developing efficient single-atom catalysts limited by their structural simplicity usually incompetent to handle this task. Incorporation of extra functional units should be viable. Herein, a proton deployment strategy is demonstrated via “atomic and nanostructured iron (A/N-Fe) pairs”, comprising atomically dispersed iron active centers spin-polarized by nanostructured iron carbide ferromagnets, to boost the critical protonation steps. The as-designed catalyst displays a broad window (300 mV) for CO selectivity > 90% (98% maximum), even outperforming numerous cutting-edge M–N–C systems. The well-placed control of proton dynamics by A/N-Fe can promote *COOH/*CO formation and simultaneously suppress H2 evolution, benefiting from the magnetic-proximity-induced exchange splitting (spin polarization) that properly adjusts energy levels of the Fe sites’ d-shells, and further those of the adsorbed intermediates’ antibonding molecular orbitals.

关键词： CO2 electrolysis     single-atom catalysts     spin polarization     proton dynamics     in situ IR spectroscopy     kinetic isotope effect    

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A novel shape memory alloy actuated soft gripper imitated hand behavior

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0700-8

摘要： The limited length shrinkage of shape memory alloy (SMA) wire seriously limits the motion range of SMA-based gripper. In this paper, a new soft finger without silicone gel was designed based on pre bent SMA wire, and the finger was back to its original shape by heating SMA wire, rather than relying only on heat exchange with the environment. Through imitating palm movement, a structure with adjustable spacing between fingers was made using SMA spring and rigid spring. The hook structure design at the fingertip can form self-locking to further improve the load capacity of gripper. Through the long thin rod model, the relationship of the initial pre bent angle on the bending angle and output force of the finger was analyzed. The stress-strain model of SMA spring was established for the selection of rigid spring. Three grasping modes were proposed to adapt to the weight of the objects. Through the test of the gripper, it was proved that the gripper had large bending amplitude, bending force, and response rate. The design provides a new idea for the lightweight design and convenient design of soft gripper based on SMA.

关键词： shape memory alloy (SMA)     pre bent     wire     gripper     grasping mode     lightweight    

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Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 448-466 doi: 10.1007/s11709-022-0910-5

摘要： In this study, a numerical analysis was conducted on aluminum alloy reticulated shells (AARSs) with gusset joints under fire conditions. First, a thermal-structural coupled analysis model of AARSs considering joint semi-rigidity was proposed and validated against room-temperature and fire tests. The proposed model can also be adopted to analyze the fire response of other reticulated structures with semi-rigid joints. Second, a parametric analysis was conducted based on the numerical model to explore the buckling behavior of K6 AARS with gusset joints under fire conditions. The results indicated that the span, height-to-span ratio, height of the supporting structure, and fire power influence the reduction factor of the buckling capacity of AARSs under fire conditions. In contrast, the reduction factor is independent of the number of element divisions, number of rings, span-to-thickness ratio, and support condition. Subsequently, practical design formulae for predicting the reduction factor of the buckling capacity of K6 AARSs were derived based on numerical analysis results and machine learning techniques to provide a rapid evaluation method. Finally, further numerical analyses were conducted to propose practical design suggestions, including the conditions of ignoring the ultimate bearing capacity analysis of K6 AARS and ignoring the radiative heat flux.

关键词： aluminum alloy reticulated shell     gusset joint     numerical analysis     fire resistance    

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Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1565-1580 doi: 10.1007/s11709-022-0867-4

摘要： This study proposes a shape optimization method for K6 aluminum alloy spherical reticulated shells with gusset joints, considering geometric, material, and joint stiffness nonlinearities. The optimization procedure adopts a genetic algorithm in which the elastoplastic non-linear buckling load is selected as the objective function to be maximized. By confinement of the adjustment range of the controlling points, optimization results have enabled a path toward achieving a larger elastoplastic non-linear buckling load without changing the macroscopic shape of the structure. A numerical example is provided to demonstrate the effectiveness of the proposed method. In addition, the variation in structural performance during optimization is illustrated. Through parametric analysis, practical design tables containing the parameters of the optimized shape are obtained for aluminum alloy spherical shells with common geometric parameters. To explore the effect of material nonlinearity, the optimal shapes obtained based on considering and not considering material non-linear objective functions, the elastoplastic and elastic non-linear buckling loads, are compared.

关键词： shape optimization     aluminum alloy     spherical reticulated shell     non-linear buckling     material nonlinearity     genetic algorithm    

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Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0720-4

摘要： Aerospace aluminum alloy is the most used structural material for rockets, aircraft, spacecraft, and space stations. The deterioration of surface integrity of dry machining and the insufficient heat transfer capacity of minimal quantity lubrication have become the bottleneck of lubrication and heat dissipation of aerospace aluminum alloy. However, the excellent thermal conductivity and tribological properties of nanofluids are expected to fill this gap. The traditional milling force models are mainly based on empirical models and finite element simulations, which are insufficient to guide industrial manufacturing. In this study, the milling force of the integral end milling cutter is deduced by force analysis of the milling cutter element and numerical simulation. The instantaneous milling force model of the integral end milling cutter is established under the condition of dry and nanofluid minimal quantity lubrication (NMQL) based on the dual mechanism of the shear effect on the rake face of the milling cutter and the plow cutting effect on the flank surface. A single factor experiment is designed to introduce NMQL and the milling feed factor into the instantaneous milling force coefficient. The average absolute errors in the prediction of milling forces for the NMQL are 13.3%, 2.3%, and 7.6% in the x-, y-, and z-direction, respectively. Compared with the milling forces obtained by dry milling, those by NMQL decrease by 21.4%, 17.7%, and 18.5% in the x-, y-, and z-direction, respectively.

关键词： milling     force     nanofluid minimum quantity lubrication     aerospace aluminum alloy     nano biological lubricant    

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Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts

WU Zhijie, LI Wei, ZHANG Minghui, TAO Keyi

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 87-95 doi: 10.1007/s11705-007-0018-4

摘要： This paper reviews the advances in the chemical synthesis and application of metal-metalloid amorphous alloy nanoparticles consisting of transition metal (M) and metalloid elements (B, P). After a brief introduction on the history of amorphous alloy catalysts, the paper focuses on the properties and characterization of amorphous alloy catalysts, and recent developments in the solution-phase synthesis of amorphous alloy nanoparticles. This paper further outlines the applications of amorphous alloys, with special emphasis on the problems and strategies for the application of amorphous alloy nanoparticles in catalytic reactions.
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Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 256-260 doi: 10.1007/s11465-010-0095-9

摘要： In the present study, samples of aluminium alloy 6060 were coated by cold spraying with a powder of brazing alloy Al12Si. The influence of the process gas temperature on particle velocities and coating build-up was investigated. The coated samples were heat-treated in air and under argon atmosphere to investigate the wetting behaviour of the deposited Al12Si and the diffusion processes between Al12Si coatings and substrates. Coated samples were brazed flux-free under argon atmosphere by an induction heating system. The microstructure of the coated, heat-treated, and brazed samples was investigated. The shear strength of the brazed joints was determined. The results show that the brazing alloy Al12Si could be very well deposited on the substrate by cold spraying. The particle velocity increased with increasing process temperature. Correspondingly, the thickness of Al12Si coatings increased with increasing process temperature. The heat treatments showed that a very good metallurgical bond between the Al12Si coatings and the substrate could be realized by the deposition using cold spraying. The coated samples could be well brazed without fluxes. The coating thickness and overlap width influenced the shear strength of the brazed joints. The highest shear strength of brazed joints amounts to 80 MPa.

关键词： aluminium alloy     flux-free brazing     cold spraying     shear strength    

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Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

《结构与土木工程前沿（英文）》 2015年 第9卷 第1期   页码 48-64 doi: 10.1007/s11709-014-0271-9

摘要： To improve the design methods of Chinese aluminum alloy members, experiment of 63 profiled aluminum alloy members, made of Chinese aluminum alloy 6061-T6, under axial compression is conducted in this paper. Valuable experimental data are obtained. At the same time, in order to obtain the relevant data, a large number of other experimental data from published papers and technical reports are collected and sorted out. 167 valid experimental data points are obtained finally. Furthermore, for the purpose of creating column curves, the aluminum alloy members under the axial compression, used in experiments, are analyzed by means of FEM. Based on the numerical results, 2 column curves are created by means of the numerical fitting method. The column curves are compared with the calculated data according to the experimental results for verification, and also are verified with the curves in design codes of several relevant countries. The numerical results show that the column curves obtained in this paper are valid and reliable.

关键词： aluminum alloy     column curve     compression members     overall stability coefficient    

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Formic acid dehydrogenation reaction on high-performance PdAu alloy nanoparticles prepared by the eco-friendly

《能源前沿（英文）》   页码 751-762 doi: 10.1007/s11708-023-0895-3

摘要： Dehydrogenation of formic acid (FA) is considered to be an effective solution for efficient storage and transport of hydrogen. For decades, highly effective catalysts for this purpose have been widely investigated, but numerous challenges remain. Herein, the PdxAu1−x (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloys over the whole composition range were successfully prepared and used to catalyze FA hydrogen production efficiently near room temperature. Small PdAu nanoparticles (5–10 nm) were well-dispersed and supported on the activated carbon to form PdAu solid solution alloys via the eco-friendly slow synthesis methodology. The physicochemical properties of the PdAu alloys were comprehensively studied by utilizing various measurement methods, such as X-ray diffraction (XRD), N2 adsorption–desorption, high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray photoelectrons spectroscopy (XPS). Notably, owing to the strong metal-support interaction (SMSI) and electron transfer between active metal Au and Pd, the Pd0.5Au0.5 obtained exhibits a turnover frequency (TOF) value of up to 1648 h−1 (313 K, nPd+Au/nFA = 0.01, nHCOOH/nHCOONa = 1:3) with a high activity, selectivity, and reusability in the FA dehydrogenation.

关键词： FA dehydrogenation     face-centred cubic structures     PdAu solid solution alloy nanoparticles     slow synthesis methodology     SMSI effect    

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Parameter prediction in laser bending of aluminum alloy sheet

WANG Xuyue, XU Weixing, CHEN Hua, WANG Jinsong

《机械工程前沿（英文）》 2008年 第3卷 第3期   页码 293-298 doi: 10.1007/s11465-008-0046-x

摘要： Based on the basic platform of BP neural networks, a BP network model is established to predict the bending angle in the laser bending process of an aluminum alloy sheet (1–2 mm in thickness) and to optimize laser bending parameters for bending control. The sample experimental data is used to train the BP network. The nonlinear regularities of sample data are fitted through the trained BP network; the predicted results include laser bending angles and parameters. Experimental results indicate that the prediction allowance is controlled less than 5%–8% and can provide a theoretical and experimental basis for industry purpose.

关键词： control     industry purpose     nonlinear     network     aluminum    

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Grindability of high-temperature alloy with ceramic alumina wheels

ZHANG Hongxia, CHEN Wuyi, CHEN Zhitong

《机械工程前沿（英文）》 2008年 第3卷 第2期   页码 139-145 doi: 10.1007/s11465-008-0040-3

摘要： The grindability of high-temperature alloy by using ceramic alumina wheels is studied on the basis of extensive analysis of the grinding force, grinding temperature, surface roughness and topography of ground surfaces, residual stress, hardness distribution of surface layer, and morphology of the surface layer from a metallographic point of view. The grinding burn mechanism of high-temperature alloy is unveiled and the feasible grinding parameters to avoid burning are analyzed. Some conclusions are obtained as follows. Increasing the grinding depth or the wheel velocity makes grinding temperature and residual tensile stress of the surface rise, which deteriorates the surface topography. Appropriate liner velocity of the wheel is 18–22 m/s and the depth of grinding should not exceed 0.02 mm in grinding GH2132 alloy with ceramic alumina wheels to assure the surface quality. When increases enough to cause grinding burn, the strengthening effect of particles ′ in base decrease and the micro-hardness of the surface is obviously lower than that of the base material, which deteriorates the mechanical properties and heat resistance of GH2132 alloy. Results provide a theoretical and experimental basis for technical optimization in the grinding of high-temperature alloy with high efficiency and high quality.

关键词： metallographic     topography     grinding GH2132     resistance     decrease    

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标题 作者 时间 类型 操作

Investigation of the preparation methodologies of Pd-Cu single atom alloy catalysts for selective hydrogenation

Xinxiang Cao,Arash Mirjalili,James Wheeler,Wentao Xie,Ben W.-L. Jang

期刊论文

Promising approach for preparing metallic single-atom catalysts: electrochemical deposition

期刊论文

Oxygen reduction electrocatalysis: From conventional to single-atomic platinum-based catalysts for proton

期刊论文

Real atom economy and its application for evaluation the green degree of a process

Weihan WANG, Jing Lü, Li ZHANG, Zhenhua LI

期刊论文

Spin polarization strategy to deploy proton resource over atomic-level metal sites for highly selective CO electrolysis

期刊论文

A novel shape memory alloy actuated soft gripper imitated hand behavior

期刊论文

Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

期刊论文

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

期刊论文

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological

期刊论文

Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts

WU Zhijie, LI Wei, ZHANG Minghui, TAO Keyi

期刊论文

Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

期刊论文

Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

期刊论文

Formic acid dehydrogenation reaction on high-performance PdAu alloy nanoparticles prepared by the eco-friendly

期刊论文

Parameter prediction in laser bending of aluminum alloy sheet

WANG Xuyue, XU Weixing, CHEN Hua, WANG Jinsong

期刊论文

Grindability of high-temperature alloy with ceramic alumina wheels

ZHANG Hongxia, CHEN Wuyi, CHEN Zhitong

期刊论文