Ni3Te2 has been reported as a highly efficient OER electrocatalyst with an overpotential of 180 mV at 10 mA cm−2 and also showing HER catalytic activity in alkaline medium.

The rational design of multifunctional catalysts that use non-noble metals to facilitate the interconversion between H2, O2, and H2O is an intense area of investigation. Bimetallic nanosystems with highly tunable electronic, structural, and catalytic properties that depend on their composition, structure, and size have attracted considerable attention. Herein, we report the synthesis of bimetallic nickel–copper (NiCu) alloy nanoparticles confined in a sp2 carbon framework that exhibits trifunctional catalytic properties toward hydrogen evolution (HER), oxygen reduction (ORR), and oxygen evolution (OER) reactions. The electrocatalytic functions of the NiCu nanoalloys were experimentally and theoretically correlated with the composition-dependent local structural distortion of the bimetallic lattice at the nanoparticle surfaces. Our study demonstrated a downshift of the d-band of the catalysts that adjusts the binding energies of the intermediate catalytic species. XPS analysis revealed that the binding energy for Ni 2p3/2 band of the Ni0.25Cu0.75/C nanoparticles was shifted ∼3 times compared to other bimetallic systems, and this was correlated to the high electrocatalytic activity observed. Interestingly, the bimetallic Ni0.25Cu0.75/C catalyst surpassed the OER performance of RuO2 benchmark catalyst exhibiting a small onset potential of 1.44 V vs RHE and an overpotential of 400 mV at 10 mA·cm–2 as well as the electrochemical long-term stability of commercial RuO2 and Pt catalysts and kept at least 90% of the initial current applied after 20 000 s for the OER/ORR/HER reactions. This study reveals significant insight about the structure–function relationship for non-noble bimetallic nanostructures with multifunctional electrocatalytic properties.

Shape memory (SM) ceramics, such as yttria-stabilized tetragonal zirconia (YSTZ), are a unique family of SM materials that offer unique properties including ultra-high operating temperature, and high resistance to chemical corrosion and oxidation. However, formation of defects is usually observed in SM ceramics during manufacturing and/or by mechanical deformation. To fully take advantage of the SM properties of these ceramics, it is necessary to fully understand the nanostructural evolution of defects under external stimuli. In this study, defect closure behaviors in YSTZ nanopillars are investigated by atomistic simulations. Two characteristic orientations of 011 and [001] are selected to represent the dominant deformation mechanisms of phase transformation and dislocation migration, respectively. With the presence of crack and void, the strength and yield strain of nanopillars are noted to decrease significantly, especially for 011oriented YSTZ nanopillars. Volume expansion associated with the tetragonal to monoclinic phase transformation is observed to promote healing of crack and void. Atom stress analyses reveal stress concentrations along the newly formed monoclinic phase bands. A critical crack width is identified, less than which the crack can be fully closed in compression. Size effect study reveals that an increase in nanopillar size has a positive effect on crack self-healing behavior. For [001]-oriented YSTZ nanopillars, dislocation migration leads to formations of an amorphous phase, which also assist the crack and void closure process. The revealed crack/void healing mechanisms may provide a path for mitigating internal defects that influences the mechanical properties and deformation mechanisms of SM ceramics.

Vane extruders are novel polymer-processing equipments, which are composed of a number of vane plasticizing and conveying units (VPCUs). With the vane extruder and the visualization VPCU device, the melting phenomenon of high-density polyethylene (HDPE) pellets under different operation conditions was investigated. It was shown that the positive displacement conveying mechanism and mandatory deformation of particles made the melting evolution in vane extruders totally different from screw extruders. The length of solid conveying and melting zone in vane extruders was much shorter, and the island-sea melting model was formed instead of Tadmor's melting model. Plastic energy dissipation, friction energy dissipation, and viscous energy dissipation were very important sources of heat energy for polymer

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