查看更多>>摘要：? 2022A rich reserve, low-cost electrocatalyst with high-efficiency catalytic activity is supposed to be a promising substitute for Pt-based noble metal electrocatalysts. Herein, we produced a heterostructure MoS2-Ni3S2 nanosphere on 3D nano-porous Ni through a novel synthetic strategy. Benefiting from the unique nanospherical heterostructure MoS2-Ni3S2 catalyst exhibits relatively low overpotentials of η10 = 109 mV and Tafel slope of 81 mV dec?1 for HER, η10 = 130 mV and 91 mV dec?1 for OER. Using heterostructure MoS2-Ni3S2 as bifunctional electrocatalysts, a low cell voltage of 1.49 V was required to reach a current density of 10 mA cm?2. The outstanding performance of heterostructure MoS2-Ni3S2 is attributed to the fast charge transfer channel offered by the interface between MoS2 and Ni3S2 as well as the large surface area provided by the nanospherical structure. This work elaborates a feasible measure to realize the non-noble and high-efficiency electrocatalysts and is instructive for the design of interface engineering and nanostructures.
查看更多>>摘要：? 2022 Elsevier B.V.Recently, an innovative process chain has been investigated and proposed, using laser-based directed energy deposition technology to produce pre-forms for forging. The advantage of this technology is to get high-performance near-formed parts at a low cost, compared traditional processing. Clarifying the hot workability and the microstructural evolution of as-deposited samples is the key to obtaining high performance parts. In present work, the plastic behaviors and dynamic recrystallization mechanisms of as-deposited nickel-based superalloy are studied. The compression curves are corrected by eliminating adiabatic heating and friction effect. And then the hot deformation activation energy and the constitutive equation of as-deposited sample are obtained. Compared to the wrought Inconel 625, as-deposited Inconel 625 has lower hot deformation activation energy (466.511 kJ/mol). The peak stress gradually decreases, while the recrystallized grain volume fraction gradually increases when deformation temperature increases and strain rate decreases. The characterization results of TEM and EBSD show that the discontinuous dynamic recrystallization mechanism nucleating by the bowing of grain boundaries occupies an absolute dominant position. In addition, combined with the microstructural evolution and hot processing map, the best hot working conditions of as-deposited Inconel 625 are obtained (deformation temperature: 1050–1150 ℃, strain rate: 0.001–0.01 s?1).
查看更多>>摘要：? 2022 Elsevier B.V.The stress-induced α’’ phase transformation in titanium alloys has received extensive attention due to its significant effect on mechanical properties. In this work, by adjusting the heat treatment process, the stress-induced α’’ phase transformation is activated in Ti-5Al-2.5Cr-5Mo-1Sn. The quasi-static tensile mechanical properties of the alloy under air-cooled and as-quenched states have been compared. Further, the morphology and orientation of the stress-induced α’’ phase and its interaction with dislocations are investigated by X-ray diffraction (XRD), optical microscope (OM), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) experiments. The value of average misorientation at the stress-induced α’’ bands region is larger than that in the β matrix, which indicates that the degree of plastic deformation in the stress-induced phase transformation region is higher. Therefore, the stress-induced α’’ phase exhibits a strong strain partitioning effect during the stretching process and improves the ductility of the material. The β/α’’ interface has a weak effect to hinder the dislocations, which results in low tensile strength of the alloy. This work can provide insight into the influence of stress-induced α’’ phase transformation on the mechanical properties of transformation induced plasticity (TRIP) type titanium alloys.
查看更多>>摘要：? 2022 Elsevier B.V.The relatively poor lifespan caused by the formation of passivation film on a Mg anode in conventional electrolytes greatly hinders the rejuvenation of magnesium ion batteries (MIBs). Therefore, it is urgent to develop novel and alternative anode materials. Noteworthy, Na2Li2Ti6O14 (NLTO) was synthesized through sol-gel method as an anode material of MIBs for the first time. Small particle size and abundant porous structure not only short ion diffusion path but also promote electrolyte permeation. Significantly, NLTO shows well electrochemical properties including long cycle life (over 300 cycles), high Coulombic efficiency and superior rate performance (91% capacity recovery rate). Furthermore, the ex-situ characterization results demonstrate that NLTO in MIBs depends on Li+ insertion/extraction to provide capacity, and it owns favorable structural reversibility and stability during cycling.
查看更多>>摘要：? 2022 Elsevier B.V.The bifunctional catalysts which can improve both oxygen evolution (OER) and oxygen reduction reaction (ORR) activity are highly desirable for fuel cells, metal-air batteries and water splitting. Here, we report a perovskite structure Sr0.9M0.1RuO3-δ (SMRO, M=K, Na, Ag) synthesized via sol-gel method performing excellent bifunctional catalytic activity. With the metal ion (M+) doping in A-site, X-ray photoelectron spectroscopy analysis reveals that oxygen vacancy and lattice oxygen are introduced into the structure, which is confirmed as the primary reason for the improvement of catalytic activity. The highest OER and ORR activity among these four samples is observed in Sr0.9Ag0.1RuO3 (SARO). This work may shed light on the designing of high-efficiency bifunctional OER/ORR electrocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.The crystal chemistry of the Al13(Fe,TM)4 (TM = Co, Cr, Ni, Pt) solid solutions has been investigated by combining formation enthalpy measurements by differential scanning calorimetry (DSC), density functional theory (DFT) calculations and thermodynamic modelling. The formation enthalpies of seven alloys of the Al13(Fe,Co)4 solid solution were measured by DSC at 920 K, allowing the determination of the mixing enthalpy of the solution. These measurements are presented here for the first time and highlight the ideal nature of this solid solution. In addition, the mixing enthalpy of the Al13(Fe,TM)4 solid solutions (TM = Co, Cr, Ni, Pt) was determined by DFT at 0 K. These calculated and measured data (in the case of the Al13(Fe,Co)4 solid solution) were used to perform thermodynamic modelling of the solid solutions and better understand their thermodynamic stability. In addition, our modelling was used to calculate the TM occupancy on the Fe sites of the Al13(Fe,TM)4 solid solution structure at different temperatures. These data were used to quantify the chemical ordering of the solid solutions as a function of temperature. While these solid solutions show significant chemical ordering at low temperatures, only the Al13(Fe,Pt)4 solution remains highly ordered at high temperatures. These data are presented for the first time in this paper and have allowed us to design an optimal sublattice (SL) model for the Al13Fe4 solid solutions.
查看更多>>摘要：? 2022 Elsevier B.V.Cobalt-based spinel oxides are promising candidates for oxygen evolution reaction (OER), however their limited electrical conductivity and low crystal stability may hinder further improvement. This report indroduces CuCo2O4 nanoparticles/Ti3C2Tx/nickel foam (NF) hybrid electrocatalyst as a robust electrode for OER, where the presence of the Ti3C2Tx MXene structure could enhance the electrical conductivity of the electrocatalysts. The ultra-thin hybrid structure with large surface area can effectively increase the number of electrochemically active sites and enhance the electrocatalytic performance. Experimental ?ndings indicated that CuCo2O4/Ti3C2Tx hybrid structure on NF shows superior improved OER electrocatalytic activity compared to pristine Ti3C2Tx. Accordingly, hybrid elecrocatalyst not only showed a low overpotential of 1.67 V at 100 mA.cm2, and a small Tafel slope of 49 mV dec?1, but also exhebited an outstanding long-term durability.
查看更多>>摘要：? 2022 Elsevier B.V.The electrocatalytic oxygen reduction reaction (ORR) plays an important role in renewable energy storage and conversion systems such as polymer electrolyte membrane fuel cells. However, design of high-performance cathode electrocatalysts is still required to speed up the sluggish kinetics of ORR. In this work, we develop a facile strategy to synthesize hierarchically porous N-doped carbon nanosheet networks with ultrafine encapsulated Fe3C and Fe-Nx for ORR by consideration of thermodynamic (intrinsic and support effect) and kinetic (diffusion effect) parameters. The synthetic process is straightforward and sustainable and the hierarchically porous materials can be synthesized directly starting from raw materials and without any additional template. The as-designed catalyst exhibits excellent ORR catalytic performance in both acidic and basic media with much positive half-wave potential and good stability, which is comparable to commercial Pt/C. The excellent ORR performance may result from highly active Fe-Nx sites and ultrafine encapsulated Fe3C, and the hierarchically porous nanosheet structure for accelerating mass diffusion and increasing exposure of the active site. This work provides a facile strategy for rational design and synthesis of highly active, hierarchically porous non-precious metal electrocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.The development of highly active electrocatalysts is of great significance to improve hydrogen production technology and promoting the development of the hydrogen energy economy. Herein, we report an electrocatalyst consisting of bimetallic carbide nanoparticles encapsulating by an N-doped carbon (NC) layer deposited on the multilayer Ti3C2Tx (denoted as Ni3Mo3C/Mo2C/Ti3C2Tx/NC) for hydrogen evolution reaction (HER) using Ti3C2Tx MXene as a conductively catalytic carrier, polyoxometalates (POM) as a soft template, in which bimetallic carbides interact with hybrid carbon. Profiting from the bimetallic character and multi-aperture structure, the Ni3Mo3C/Mo2C/Ti3C2Tx/NC catalyst represents an overpotential of 99 mV in acidic medium and 98 mV in alkaline medium at 10 mA cm?2 with extended durability for 24 h. The turnover frequency (TOF) at 100 mV overpotential for Ni3Mo3C/Mo2C/Ti3C2Tx/NC electrocatalyst is 0.188 s?1. The remarkable catalytic activity for Ni3Mo3C/Mo2C/Ti3C2Tx/NC electrocatalyst can be attributed to the synergistic effects of bimetallic carbides. In addition, the introduction of Ti3C2Tx MXene further strengthened the conductivity of the catalyst as well as accelerated proton transport. Moreover, the protective effect of the porous carbon layer and the adulteration of the N atom increased the active site, resulting in improved HER properties. This simple preassembly-thermal conversion strategy offers a novel approach for the designing of superior electrocatalysts for HER.
查看更多>>摘要：? 2022 Elsevier B.V.Though two-dimensional metal chalcogenides are a promising anode material for Li-ion batteries owing to their high theoretical capacity, they exhibit poor cycling stability and inferior rate performance due to their structural deterioration caused by huge volume change during the repeated cycling. Herein, we report extra-small tin sulfide quantum flakes with nitrogen-doped carbon over two-dimensional molybdenum sulfoselenide microspheres (SnS QFs/NC@MoSSe) to improve the lithium ion-storage capability. The exclusive design of SnS QFs/NC@MoSSe endows the heterostructure with the large surface area, improves charge storage kinetics, maintains robust structural stability and exaggerates ion storage ability. An initial discharge capacity of 962 mAh g?1 is obtained at 100 mAg?1 with good cycling stability (1026 mAhg?1 after 100 cycles) and superior rate capability (628 mAhg?1 at 2000 mA g?1). The full cell with SnS QFs/NC@MoSSe anode and LiNi0.8Co0.1Mn0.1O2 cathode exhibits good cycling performance with a capacity retention of 90.0% after 300 cycles at 0.5 C rate. Our work provides the feasible design of anchoring/infusing quantum-sized active materials into the various two-dimensional structures for the development of high-performance anode materials for advanced Li-ion batteries.
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