查看更多>>摘要：Recently, the 2021 United nations climate change conference (COP26) have again stressed on the need of carbon neutral economy. To cope up with the power hunger of industrial and/ technological world of hybrid electric vehicles and portable electronic devices it is imperative to search the environment friendly novel materials with property tailoring abilities. In this connection, we have deposited Co1-xCuxS/CoCuS (0.025 ≤ x ≤ 0.1) thin-films via chemical route as an alternative material for supercapacitor application. To asses the suitability of as-deposited thin films, we have characterized thin films using variety of characterization techniques. X-ray photoelectron spectroscopy was used to examine and confirm the chemical states of Co, Cu, and S. Surface morphology of as-deposited CoCuS film (x = 0.075, sample-C3) showed a crumpled flower-like microstructure. Uniform distribution of hillocks and valleys was observed using atomic force microscopy. The topographical outcomes obtained from electrostatic force microscopy and Kelvin probe force microscopy confirmed that the sample-C3 (x = 0.075) is suitable for energy storage applications. Sample-C3 demonstrated excellent supercapacitive performance with a high specific capacitance of 907.55 F g?1 at 5 mV s?1, remarkable rate capability, and ~ 90% of capacitive retention after 5000 cycles in a 1 M KOH electrolyte. Better supercapacitive behavior and cycling stability of the CoCuS samples may offer a perspective for various mixed metal sulfide thin films with hierarchical architectures as an viable alternative for the efficient energy storage devices.
查看更多>>摘要：We loaded palladium (Pd) nanoparticles (NPs) onto a flower-like boron (B), nitrogen (N) doped carbon carrier via a cobalt reduction path. The B, N co-doped flower-like carbon carrier itself (BNCF-800) was prepared by the pyrogenation process of flower-like cobalt boronoisophthalic acid (Co-BA), which was produced through the coordination between Co2+, derived from the zeolitic imidazolate frameworks (ZIF-67), and 5-boronoisophthalic acid. The abundant activity sites caused by B, N doped carbon are able to anchor the Pd nanoparticles further during the cobalt reduction process to prevent the agglomeration of Pd NPs on the BNCF-800 carrier. The flower-like construct of carbon composites also offers more open spaces and paths to promote mass and charge transmission in the catalyst process. Hence, the palladium catalyst immobilized on the flower-like B, N doped carbon exhibited electro-catalyst performance toward an ethanol oxidation reaction (EOR). The mass activity of the Pd/BNCF-800 was 1989.20 mA mg?1, which is 2.84 times that of the Pd/C in the basic electrolyte.
查看更多>>摘要：A systematic study of the Zr-Ta-B system was performed using thermodynamic and ab initio modeling, nanoindentation, and high-resolution TEM and XRD experiments. The phase diagram (convex hull) of the Zr-Ta-B system was constructed at 0 K, and phase stability, lattice parameters, and mechanical properties of ZrB2-TaB2 solid solutions were ascertained in silico. Dense ceramics were manufactured by the combination of combustion synthesis and hot pressing techniques. As opposed to theoretically predicted complete solubility in the ZrB2-TaB2 solid solution series, the highest experimentally attained Ta content in the ZrB2-based solution was 25–27 at%, suggesting that at higher Ta contents a non-equilibrium phase composition is formed during combustion synthesis and inherited during hot pressing. Single-phase ZrB2-TaB2 solid solutions displayed a super-hardness up to 70 GPa and coefficient of elastic recovery as high as 99.7%, which surpasses wurtzite and cubic boron nitride and rivals polycrystalline diamonds. In the non-equilibrium samples with multiple solid solutions, a “pop-in” (localized plastic deformation) effect was discovered and attributed to the formation of shearing bands, microtwins, and dislocation loops. The composition-dependent switching between super-hardened and locally plastic mechanical behavior allows the creation of a new generation of ultra-high temperature ceramic composites.
查看更多>>摘要：New infrared nonlinear optical (IR NLO) crystals with strong NLO efficiency, high laser damage threshold, excellent phase-matching ability and good IR transmittance, are urgently desirable because the commercial IR NLO materials (e.g., AgGaS2, AgGaSe2, and ZnGeP2) with inevitable defects are limited for high power laser applications. Pnictides are highly promising IR NLO candidate materials due to their probably large second-order NLO coefficient. After years of silence, the exploration on pnictide NLO crystals has emerged bring out numbers of excellent IR NLO pnictides. This review summarizes the achievements on IR NLO pnictides by focusing on their crystal structures and several key NLO indexes, and then get deep insight into their structure-property correlations. Furthermore, the existing issues and prospective development of NLO pnictides are also proposed and discussed.
查看更多>>摘要：Interfacial bond and structure as key points significant restrict the mechanical properties of carbon nanotubes (CNTs) reinforced aluminum matrix composites (CNTs/Al composites). In order to further enhance the interfacial bond of CNTs/Al composites, this paper proposed a novel fabrication process of CNTs/Al composites with Cu nanoparticles decorated CNTs, which results in the remarkable improvement of strength and ductility of CNTs/Al composites. The in-depth study results from microstructure of layered CNTs/Al composites show that: Cu nanoparticles can repair CNTs structural defects, and passivate the reaction activity of the defect points, which successfully inhibit producing big Al4C3 phase. On the other hand, Cu nanoparticles as a bridge connecting Al and CNTs, can improve the interface wettability, and produce an “Al-Cu-CNT” interlocking effect. Due to the improvement of the interfacial bond and structure between CNTs and Al matrix, the strengthening and toughening effect of CNTs is effectively exerted in the Al matrix composites. Additionally, this work avoids the traditional mismatch relationship between strength and ductility in CNTs/Al composites.
查看更多>>摘要：To understand the microstructural stability of candidate plasma-facing materials under fusion-relevant environments, neutron irradiation of W and W-3%Re alloys with and without K and La dopants was performed in the mixed-spectrum High Flux Isotope Reactor at nominal temperatures of ~850 °C and ~1100 °C to calculated doses between 0.42 and 0.47 dpa. To the best of our knowledge, this study presents the first experimental evidence of radiation-enhanced recrystallization in W and undoped W–Re alloys at ~850 °C, conditions where thermal annealing does not cause any grain growth in a similar timescale. Potassium- or lanthanum-doped tungsten alloys showed more resistance to radiation-enhanced grain growth. We explain the acceleration of grain growth by analyzing the self-diffusion constant under atomic displacement environments. The microstructural observations of the studied W variants suggest that La doping is more effective than K doping for mitigating recrystallization. This study also found that radiation-enhanced recrystallization is an important consideration when designing and applying W to plasma-facing components in future nuclear fusion reactors.
查看更多>>摘要：In this study, the thermal expansion behavior of ZK60 magnesium alloy was investigated under different precipitation hardening and extrusion conditions. The alloy samples were subjected to precipitation hardening at temperatures of 125, 175, and 225 °C for 6, 12, 18, 24, and 30 h, and extrusion process at ratios of 1:6, 1:8, 1:12, and 1:18 to evaluate the effects of volume fraction of precipitates and grain size on the thermal expansion behavior of the alloy. Microstructure characterizations showed that the precipitates with needle and cloudy morphologies and uniform distribution were formed in the samples. It was revealed that the size and volume fraction of the precipitates were highly dependent on the process conditions. Microhardness measurement results demonstrated that the sample treated at 175 °C for 12 h submitted the highest hardness. Also, the dilatometry test results confirmed that the presence of precipitates resulted in a decrease in the coefficient of thermal expansion; so that the lowest value was obtained for the sample aged at 175 °C. Furthermore, it was concluded that the matrix grain size and volume fraction of the precipitates affected the thermal expansion behavior of the ZK60 magnesium alloy.
查看更多>>摘要：Ferromagnetic alloys of the Mn-Al system are promising materials for permanent magnets and details of electric motors. Deformation methods of processing these alloys allow obtaining high magnetic properties, however, they are still not well researched. In the current study the effect of the τ-MnAl alloy structure obtained by severe plastic deformation on the phase composition, structure, and magnetic properties gained during subsequent annealing is investigated. It was shown that a twinned structure is preferable for recrystallization (in terms of recrystallized volume) than a dislocation one. The largest coercive force of 3.7 kOe was reached in the current investigation after deformation by 20 revolutions (ε ≈ 6.83). Subsequent annealing led to a drastic fall in coercive force due to vanishing of defects (dislocations and nanotwins) acting as sites of domain wall pinning.
查看更多>>摘要：MXenes have been considered as a promising electrode material for Na+ or K+ storage due to their high conductivity, large specific surface area and unique 2D layered structure. However, their tendency to restacking limits the penetration of electrolyte, resulting in poor energy storage capacity. In efforts to overcome this obstacle and take full advantage of Ti3C2Tx MXene, herein, Ti3C2Tx MXene/CNT hybrid has been rationally fabricated as the anode for high-performance sodium- and potassium-ion storage through a surfactant-free assembly strategy assisted by hydrochloric acid (HCl). The HCl-assisted assembly can realize the assembly of Ti3C2Tx MXene and CNT on the nanoscale to make full use of the advantages of CNT as a spacer. Moreover, highly conductive CNT can also provide more diffusion paths for electrons and sodium/potassium ions. Benefiting from the synergistic effect between CNT and Ti3C2Tx flakes, the Ti3C2Tx/CNT hybrid has exhibited excellent electrochemical properties for sodium- and potassium-ion storage. It is worth emphasizing that the Ti3C2Tx/CNT electrode also has superior rate capability, which outperforms that of most reported literatures. This work proposes a new strategy for introducing CNT between MXene layers, which could be expected to be an effective strategy to exert the attracting surface functionality for target applications.
查看更多>>摘要：Bandgap engineering has attracted increasing interest in the field of semiconductive materials with specific electrical and optical characteristics for various applications, such as solar energy harvesting, energy-related applications, and photocatalysts. Here, we propose a novel and facile method to obtain a combination of type-II structure and Ohmic contact by the fabrication of WO3/Ti-WOx/TiHyOz homo/heterojunction on a WO3 photocatalyst using ball milling. The morphology and structural characterizations of the material are obtained using UV–vis, SEM/EDS, XRD, Raman spectroscopy, and XPS. It is revealed that titanium hydride (TiH2) facilitates simultaneous WO3 reduction and cation doping, which generates intervalent W ions (W5+, W4+) with oxygen deficiency, leading to the formation of new band structures at the WO3/Ti-WOx/TiHyOz interface. As a result, the homo/heterojunction significantly extends light absorption above 400 nm and facilitates the spatial separation of photoexcited carriers, which significantly enhances the photocatalytic performance to degrade azo-dye water pollutants under visible light irradiation.
NSTL
Elsevier