Herein, a 3D hierarchical structure is constructed by growing NiCo₂O₄ nanowires on few-layer Ti₃C₂ nanosheets using Ni foam (NF) as substrate via simple vacuum filtration and solvothermal treatment. Ti₃C₂ nanosheets are directly anchored on NF surface without binders or surfactants, and NiCo₂O₄ nanowires composed of about 15 nm nanoparticles uniformly grow on Ti₃C₂/NF skeleton, which can provide abundant active sites and ion diffusion pathways for enhancing electrochemical performance. Benefiting from the unique structure feature and the synergistic effects of active materials, NiCo₂O₄/Ti₃C₂ exhibits a high specific capacitance of 2468 F g⁻¹ at a current density of 0.5 A g⁻¹ and a good rate performance. Based on this, an asymmetric supercapacitor (ASC) based on NiCo₂O₄/Ti₃C₂ as positive electrode and activated carbon (AC)/NF as negative electrode is assembled. The ASC achieves a high specific capacitance of 253 F g⁻¹ at 1 A g⁻¹ along with 91.5% retention over 10,000 cycles at 15 A g⁻¹. Furthermore, the ACS presents an outstanding energy density of 90 Wh kg⁻¹ at the power density of 2880 W kg⁻¹. This work provides promising guidance for the fabrication of binder-free, free-standing and hierarchical composites for energy storage application.

Intermetallic compounds are increasingly being expected to be utilized in tribological environments, but to date their implementation is hindered by insufficient ductility at low and medium temperatures. This paper presents a novel multiphase intermetallic alloy with the chemical composition of Mo–40Ni–13Si (at %). Microstructure characterization reveals that a certain amount of ductile Mo phases formed during the solidification process of a ternary Mo–Ni–Si molten alloy, which is beneficial to the improvement of ductility of intermetallic alloys. Tribological properties of the designed alloy—including wear resistance, friction coefficient, and metallic tribological compatibility—were evaluated under dry sliding wear test conditions at room temperature. Results suggest that the multiphase alloy possesses an excellent tribological property, which is attributed to unique microstructural features and thereby a good combination in hardness and ductility. The corresponding wear mechanism is explained by observing the worn surface, subsurface, and wear debris of the alloy, which was found to be soft abrasive wear.

As a graphene-like material, h-BN has stimulated great research interest recently due to its potential application for next-generation electronic devices. Herein, a systematic theoretical investigation of electronic structures and optical properties of C-doped and Cu-Al co-doped h-BN is carried out by the first-principles calculations. Firstly, two different C-doped h-BN structures for the para-position and ortho-position are constructed. The results show that the C ortho-doped h-BN (BCN) structure with a band gap of 3.05 eV is relatively stable, which is selected as a substate to achieve the Cu-Al co-doped h-BN. Based on this, the effect of the concentration of C atom doping on the electronic and optical properties of Cu-Al co-doped BC_xN (x = 0, 11.1% and 22.2%) is investigated. The results demonstrate that the band gap of Cu-Al co-doped BC_xN decreases and the optical properties improve with the increase in C atom concentration. The band gap and static dielectric constant of Cu-Al co-doped BC₀N, BC₁N and BC₂N are 0.98 eV, 0.87 eV and 0.23 eV and 2.34, 3.03 and 3.77, respectively. As for all Cu-Al co-doped BC_xN systems, the adsorption peak is red-shifted, and the peak intensity obviously decreases compared to the undoped h-BN. Additionally, the Cu-Al co-doped BC₂N exhibits the best response to visible light. This work will provide valuable guidance for designing and developing h-BN-based doping systems with good performance in the field of optical and photocatalysis.

Hexagonal boron nitride (h-BN) nanoparticles have attracted increasing attention due to their unique structure and properties. However, it is difficult to synthesize h-BN nanoparticles with uniform spherical morphology due to their crystal characteristic. The morphology control by tuning their precursor synthesis is a promising and effective strategy to solve this problem. Especially, the treatment temperature of precursors plays an important role in the morphology and surface area of h-BN nanoparticles. Herein, h-BN nanoparticles with different morphologies were synthesized via regulating the treatment temperature of precursors. The result shows that treatment temperature will affect the microstructure and state of precursor and further influence the morphology of h-BN products. Benefiting from the unique structure, the h-BN obtained using 250 °C precursors shows higher specific surface area (61.1 m² g⁻¹) than that of 85 °C (36.5 m² g⁻¹) and 145 °C (27.9 m² g⁻¹). h-BN products obtained using 250 °C precursors show higher specific surface area than that of 85 °C and 145 °C. The optimal condition for obtaining high-quality spherical h-BN is the pretreatment temperature of 250 °C and sintering temperature of 1300 °C. Importantly, compared with commercial h-BN nanoparticles, the synthesized h-BN nanoparticles show more uniform structure and larger specific surface area, indicating that sintering activity will be greatly improved. Furthermore, the reaction pathway and formation mechanism of h-BN was revealed by DFT calculations. The result shows that the five stationary states and five transition states exist in the reaction pathway, and the energy barrier can be overcome at high temperatures to form a ring h-BN. In view of its simplicity and efficiency, this work is promising for designing and guiding the synthesis of h-BN nanoparticles with uniform morphology.