Three-dimensional flower-like NiCo2O4 hierarchitectures have been successfully prepared on a large scale via a facile solvothermal method followed by an annealing process. The as-synthesized NiCo2O4 flower-like architectures have uniform diameters of about 500 nm assembled by numerous nanosheets radially grown from the center. The possible growth mechanism of the unique structures has been investigated. Both the poly(vinylpyrrolidone) (PVP) surfactant and the formation of metal glycolate play important roles in the formation of these novel three-dimensional flower-like hierarchitectures. With a large surface specific area of 212.6 m2 g−1, this novel NiCo2O4 material exhibited a superior specific capacitance of 1191.2 F g−1 and 755.2 F g−1 at current densities of 1 and 10 A g−1, respectively, which suggests that 63.4% of the capacitance is still retained when the charge–discharge rate is increased from 1 A g−1 to 10 A g−1. This superior electrochemical performance of NiCo2O4 as an electrode material for supercapacitors can be ascribed to the synergetic effect of the porous structure and the small diffusion lengths in the nanosheet building blocks. The simple, versatile and cost-effective route reported here may provide a general methodology for the high-yield synthesis of metal cobaltite nanostructures featuring improved properties and structures.

Ni₂P nanoparticles grown on reduced graphene oxide (rGO) were successfully synthesized via the low-temperature solid state reaction method and investigated as electrochemical pseudocapacitor materials for potential energy storage applications. The specific capacitance of the as-prepared Ni₂P/rGO is 2266 F g⁻¹ and the Ni₂P/rGO composite also exhibits superior cycling performance when they are used as the capacitor materials. The as-prepared Ni₂P/rGO sample demonstrates interesting supercapacitive properties with high capacitance and good cycling performance.

Highly crumpled graphene nanosheets (GNS) with a BET surface area as high as 1159 m2 g−1 was fabricated by a thermal exfoliation method. A systematic investigation was performed on the hydrogen sorption properties of MgH2–5 wt% GNS nanocomposites acquired by ball-milling. It was found that the as-synthesized

We have demonstrated an extremely facile procedure for the preparation of 1D porous Ni@C nanostructures by pyrolysis of Ni-based coordination polymer nanorods. The highly aligned Ni-based polymer nanorods were prepared using nitrilotriacetic acid (NTA) as a chelating agent by a one-step solvothermal approach. The obtained precursors are demonstrated to have a well-designed 1D nanostructure and a 3D interconnected mesoporous texture. After thermal treatment, 1D porous Ni@C nanorods were obtained, which basically preserved the morphology of the precursors. In addition, the carbon in the porous Ni@C nanorods is in both crystalline and amorphous states. The as-prepared Ni@C sample displays nanorod-like morphology with about 3 μm length and about 200 nm diameter. With a large surface area of 161.4 m2 g−1, this novel material had a good catalytic effect on de/hydrogenation of MgH2. The desorption peak temperature of MgH2–5 wt% Ni@C composites can be lowered more than 57 °C than the pure as-milled MgH2. The MgH2–5 wt% Ni@C composite could desorb 6.4 wt% H2 within 10 min at 300 °C, in contrast, only 2.3 wt% H2 was desorbed even after 100 min for pure MgH2. In addition, an activation energy of 108 kJ mol−1 for the as-milled MgH2–5 wt% Ni@C composites has been obtained, which exhibit an enhanced kinetics.

To realize high-rate and long-term performance of rechargeable batteries, the most effective approach is to develop an advanced hybrid material with a stable structure and more reaction active sites. Recently, 2D MXenes have become an up-and-coming electrode owing to their high conductivity and large redox-active surface area. In this work, we firstly prepared Ti₃C₂ MXenes through the selective etching of silicon from Ti₃SiC₂ (MAX) using HF and an oxidant for highly durable lithium-ion batteries (LIBs). The interlayer distance of Ti₃C₂ MXenes can be controlled with the oxidizability of the oxidant and etching temperature. In addition, Ti₃C₂@TiO₂ MXene hybrids with further expanded interlayer spacing were purposefully fabricated by a simple hydrothermal method. The hierarchical N-doped Ti₃C₂@TiO₂ MXene hybrids show that the in situ synthesized nanoscale TiO₂ particles are loaded homogeneously on the layered N-doped Ti₃C₂ surface. The interlayer distance of N-doped Ti₃C₂@TiO₂ MXene can reach 12.77 Å when using HNO₃ as the oxidant at room temperature. As an anode material, the N-doped Ti₃C₂@TiO₂(HNO₃-RT) hybrid displays a high reversible capacity of 302 mA h g⁻¹ at 200 mA g⁻¹ after 500 cycles and 154 mA h g⁻¹ at 2000 mA g⁻¹ after 1500 cycles, which indicates its long cycle lifetime and excellent stability in LIBs. This highly durable LIB anode performance is ascribed to synergetic contributions from the high capacitive contribution, high electrical conductivity, high-capacity of in situ formed nanoscale TiO₂ and interlayer-expanded architecture of the N-doped Ti₃C₂@TiO₂(HNO₃-RT). This study provides a theoretical basis for the application of MXenes as high capacity anodes for advanced LIBs.