[en] Highly-crystallized cubic cattierite CoS_2 pyramids were deposited on Ti foil via a simple hydrothermal method using CoCl_2 and thiourea as precursors. Scanning electron microscopy (SEM) characterization revealed the morphology evolution from ramdom nanoparticles to micro-pyramids with well defined facets. These CoS_2 pyramids were applied as electrocatalysts for hydorgen evolution reaction (HER) and showed very different acidic HER performance. The sample prepared at 15 h reaction time showed the best performance with an onset overpotential as low as 81 mV and a Tafel slope of ∼72 mV/dec. The activity was kept almost 89% even after working for 30,000 seconds. Further study showed that these CoS_2 pyramids also functioned well in neutral (1.0 M potassium phosphate buffer solution, pH = 7.00) and alkaline (1.0 M KOH solution, pH = 13.57) conditions. The cubic cattierite-type CoS_2 can work as a novel HER electrocatalyst over the wide pH range from 0 to 14, combined with its easy-synthesis, low-cost and high stability, which can potentially serve as a ready-to-go HER catalyst for practical utilization

[en] This paper discusses two deterministic quantities, mean first exit time and escape probability, for the anomalous processes having the tempered Lévy stable waiting times with the tempering index $\mathrm{\mu <!--\; ??\; -->}>0$ and the stability index $0<\mathrm{\alpha <!--\; ??\; -->}\le <!--\; ???\; -->1$. We derive the nonlocal elliptic partial differential equations (PDEs) governing the mean first exit time and escape probability. Based on the analysis of the derived PDEs, some interesting phenomena are observed. (letter)

[en] Strongly intensive quantities Σ[P _T, N] and Δ[P _T, N] have become one of the important tools in study of phase transitions and critical points in high energy heavy-ion collisions. In this paper the properties of Σ[P _T, N] and Δ[P _T, N] are discussed within different colliding nuclei systems generated by the AMPT model. The combined event method are proposed to simulate the model of independent sources in which Σ[P _T, N] and Δ[P _T, N] are independent of the number of original events. The effects of transverse momentum, pseudorapidity and parton cascade are also discussed. (paper)

[en] Highlights: • Hierarchical mesoporous NiO nanoarrays show an ultrahigh specific capacitance beyond its theoretical faradaic capacitance. • A self-generated sacrificial template approach was developed to prepare the 3D hierarchical and mesoporous array structure. • The ultrahigh capacitance is ascribed to the combination of faradaic and electrical double-layer capacitance. • The hybrid supercapacitor made of NiO-HMNAs and MGMs showed a high energy density and outstanding cycleability. Hybrid supercapacitors (HSCs), which usually involve faradaic or pseudocapacitive positive materials and electric double-layer capacitive negative materials, have demonstrated great potentials with enhanced energy density outdistancing traditional electrical double-layer capacitors. To endow materials with higher energy density and power density, the rational design and synthesis of electrodes with hierarchical and mesoporous structure are highly desired. In this work, we report the fabrication of hierarchical mesoporous NiO nanoarrays (NiO-HMNAs) as a battery-type electrode for hybrid supercapacitor with an ultrahigh specific capacitance (3114 F g⁻¹ at the current density of 5 mA cm⁻²), which is beyond the theoretical faradaic capacitance value of NiO. NiO-HMNAs were prepared by a self-generated sacrificial template approach, which involves the preparation of hierarchical ZnO/NiO composites by co-deposition of Zn²⁺ and Ni²⁺ and the removal of ZnO by an alkali etching process to construct mesoporous structure. The ultrahigh capacitance of NiO-HMNAs is ascribed to the nearly full redox reaction of NiO in the unique hierarchical mesoporous architecture, and the raised electrical double-layer capacitance at the enlarged surface of nanoarrays. Moreover, the optimized HSC fabricated by using NiO-HMNAs as the positive electrode and macroporous graphene monoliths (MGMs) as the negative electrode has demonstrated a high energy density of 67.0 W h kg⁻¹ at a power density of 320 W kg⁻¹ with a maximum voltage of 1.6 V and outstanding cycleability (capacitance retention of 89.6% after 6000 cycles).

[en] Highlights: • W-Al₂O₃ ultrafine powder was prepared by hydrothermal synthesis. • Al₂(WO₄)₃ was a key process for forming nano-Al₂O₃ coated W structure. • This coated structure inhibited the further growth of W particles. • Dispersed Al₂O₃ particles improved obviously mechanical properties of W alloy. • Fracture mode changed into intergranular from transcrystalline with Al₂O₃ addition. - Abstract: W-Al₂O₃ composite powder was prepared via hydrothermal synthesis containing doping, annealing and reduction. The precursors WO₃ and AlOOH were synthesized by the two sets of the hydrothermal reactions, respectively. The formation of Al₂(WO₄)₃ from these two precursors in an aqueous solution is a key process, which is beneficial to improve the mixing uniformity of final powder to a molecular level. During subsequent reduction, nano-Al₂O₃ coated W particles were obtained, and inhibited the further deposition of reduced W atoms on the adjacent W particles, obtaining ultra-fine Al₂O₃/W composite powder. After sintering, the dense and fine-grained W-Al₂O₃ alloy was obtained due to the high sintering activity of ultra-fine powder. Compared with the pure tungsten, the W-Al₂O₃ alloy displays obvious higher values of both strength and plasticity especially when the Al₂O₃ content is 2 wt%.

[en] Highlights: • Typical microstructure of F82H–ODS steel is observed. • The existence of a meta-stable ferrite phase in F82H–ODS steel is confirmed. • The microstructure can be modified by the coarsening of the oxide particles. • The relationship between the phase formation and oxide particles is revealed. - Abstract: For the reduced activation F82H–ODS ferritic steel developed as the advanced fusion blanket material, the structure control and phase formation mechanisms were investigated. The area fraction of the ferrite phase was reduced, when the specimens were annealed at 1250 °C for long enough time inducing oxide particle coarsening. The effect of oxide particles on α–γ transformation was investigated, and ferrite formation is ascribed to pinning of α–γ interfacial boundaries by the dispersed oxide particles. This ferrite is meta-stable, and designated as residual-ferrite

[en] Highlights: •Hot-rolling can induce a coarser ferrite grain in 8CrODS ferritic steel. •HR specimen consists of martensite, residual ferrite and transformed ferrite. •The coarsening of the transformed ferrite was analyzed by EBSD. •Hot-rolling can improve the strength of 8CrODS ferritic steel at 700 °C. -- Abstract: The 8CrODS ferritic steel is based on J1-lot developed for the advanced fusion blanket material to increase the coolant outlet temperature. A hot-rolling was conducted at the temperature above A_r3 of 716 °C, and its effect on the microstructure and tensile strength in 8CrODS ferritic steel was evaluated, comparing together with normalized and tempered specimen. It was confirmed that hot-rolling leads to slightly increased fraction of the ferrite and highly improved tensile strength. This ferrite was formed by transformation from the hot-rolled austenite during cooling due to fine austenite grains induced by hot-rolling. The coarsening of the transformed ferrite in hot-rolled specimen can be attributed to the crystalline rotation and coalescence of the similar oriented grains. The improved strength of hot-rolled specimen was ascribed to the high dislocation density and replacement of easily deformed martensite with the transformed coarse ferrite

[en] Spherical porous Al₂O₃ nanoparticles were synthesized by hydrothermal method using C₆H₅(NH₄)₃O₇·2H₂O and Al(NO₃)₃·9H₂O as raw materials. The morphology and size of the Al₂O₃ particles were significantly influenced by hydrothermal temperature, time, and the molar ratio of Al³⁺ to (C₆H₅O₇)³⁻. The interphase Al(OH)₃ is a key factor on the preparation of γ-Al₂O₃. Under the hydrothermal conditions of high temperatures, Al(OH)₃ decomposes into the precursor γ-AlOOH instead of the exothermic reaction between Al(OH)₃ and H⁺. In the form of hydrogen bonds, (C₆H₅O₇)³⁻ adsorbs on the surface of γ-AlOOH nanoparticles to form some nano-chains, which interweave and tangle each other to become spheres. During calcination, the precursor γ-AlOOH converts to γ-Al₂O₃ nanoparticles while the spherical morphology is retained. Gas outrush during calcination should be the formative cause of the porous structure. The as-prepared spherical porous Al₂O₃ nanoparticles can be used as a catalyst or carrier due to the favorable adsorption property. (paper)

[en] Highlights: • Highly homogeneous LiNi_0.6Co_0.2Mn_0.2O₂ and LiNbO₃-coated LiNi_0.6Co_0.2Mn_0.2O₂ thin-film electrodes were fabricated via RF sputtering deposition. • The prepared-LiNbO₃ layer had an ionic conductivity of 1.32 × 10⁻⁵ S cm⁻¹. • The interface between LiNi_0.6Co_0.2Mn_0.2O₂ and LiNbO₃ layers was investigated by XPS depth profiling. • The modified LiNi_0.6Co_0.2Mn_0.2O₂ cathode shown better stability and mitigated the impedance increase after cycling. • Post-mortem analyses revealed the stability of the LiNbO₃/LiNi_0.6Co_0.2Mn_0.2O₂ interface and moderate CEI formation. -- Abstract: Ni-rich LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) and LiNbO₃-protected LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) thin-film cathodes have been prepared by radio frequency (RF) magnetron sputtering. Electrochemical investigations show enhanced stability of LiNbO₃-protected cathodes compared with bare LiNi_0.6Co_0.2Mn_0.2O₂. The interfacial interaction of LiNbO₃ and LiNi_0.6Co_0.2Mn_0.2O₂ layers has been investigated by XPS depth profiling and demonstrated different cathode electrolyte interface (CEI) film formation processes at the electrodes. The results elaborate on the interaction between LiNbO₃ and LiNi_0.6Co_0.2Mn_0.2O₂, emphasizing the role of the LiNbO₃ layer in improving the cycling performance of Ni-rich cathodes.

[en] The olivine polymorph LiCoPO₄ was synthesized by solvothermal and a subsequent annealing process. Carbon free, ex-situ carbon coated and in-situ carbon coated materials were prepared. With the addition of citric acid in the solvothermal reaction, a carbon layer was coated via an in-situ approach. To systematically compare the different carbon coating routes, the structure and morphology of the LiCoPO₄ materials were investigated by XRD, Raman, and SEM. HAADF-STEM combined with EDX was applied to analyze the homogeneity of the carbon layer and corresponding antisite defects. Electrochemical properties were analyzed by half-cells measuring cyclic-voltammograms, charge/discharge cycling behavior stability and rate-capability. It was found that the in-situ carbon coated LiCoPO₄/C exhibited a superior electrochemical performance due to the relatively uniform and complete surface-layer formation. As a result, an appropriate carbon layer improves the electronic and ionic transport properties, ensures fast electron-transfer kinetics at the electrode particle surfaces and suppresses unwanted side reactions with the electrolyte.