The nickel oxide nano-flakes materials prepared by a facile approach maintain high power density at high rates of discharge and have excellent cycle life, suggesting their potential application in supercapacitors.

CoMoO₄–NiMoO₄·xH₂O bundles with excellent electrochemical behavior were designed and synthesized by a facile strategy. CoMoO₄ nanorods were fabricated by a chemical co-precipitation method, and then CoMoO₄–NiMoO₄·xH₂O bundles were prepared by the same method using the CoMoO₄ nanorods as the backbone material. A growth mechanism was proposed to explain the formation of the bundles. The composites combine the advantages of the good rate capability of CoMoO₄ and the high specific capacitances of NiMoO₄·xH₂O, showing higher specific capacitances than CoMoO₄ and a better rate capability than NiMoO₄·xH₂O. A maximum specific capacitance of 1039 F g⁻¹ was achieved at a current density of 2.5 mA cm⁻², and 72.3% of this value remained at a high current density of 100 mA cm⁻². The excellent electrochemical performance makes the composite a promising electrode material for electrochemical capacitors.

Water splitting, to produce hydrogen and oxygen, has long been considered to be a desirable option for the storage of electrical energy. The catalysts for oxygen evolution reactions (OER) are very important in this process. Herein, we have synthesized Co₃V₂O₈ nanoparticles by a simple and cost-effective technique, which have low crystallinity and large specific surface area (122.8 m² g⁻¹). Because of the low crystallinity, large specific surface area and suitable pore size, Co₃V₂O₈ nanoparticles yielded an electrocatalytic OER current density of up to 429.7 mA cm⁻² at 2.05 V vs. RHE and low OER over potentials of 359 mV (at 10 mA cm⁻²) and 497 mV (at 100 mA cm⁻²). In addition, the OER stability of the Co₃V₂O₈ catalyst was very excellent, and the current density at 2.05 V was reduced by just 7.3% after galvanostatic OER measurement at 10 mA cm⁻² for 3 h. This work demonstrates that binary metal oxides Co₃V₂O₈ is a highly active and stable oxygen evolution electrocatalyst that can potentially replace expensive noble metal-based anode catalysts for electrochemical water splitting to generate hydrogen fuels.

Binary metal oxides have recently attracted extensive attention from researchers in the energy storage field due to their multiple oxidation states and high energy density. In the present work, Ni₃V₂O₈, Co₃V₂O₈, and the Ni₃V₂O₈/Co₃V₂O₈ nanocomposite are designed and synthesized as a new class of high performance electrode material for supercapacitors. Ni₃V₂O₈ and Co₃V₂O₈ show a structure comprising nanoflakes and nanoparticles, respectively. The Ni₃V₂O₈/Co₃V₂O₈ nanocomposite is prepared by growing Co₃V₂O₈ nanoparticles on the surface of Ni₃V₂O₈ nanoflakes. The composite inherits the structural characteristics and combines the pseudocapacitive benefits of both Ni₃V₂O₈ and Co₃V₂O₈, showing higher specific capacitance than Co₃V₂O₈ and superior rate capability as well as better cycle stability to Ni₃V₂O₈. The dependence of pseudocapacitive properties of the Ni₃V₂O₈/Co₃V₂O₈ nanocomposite on the Ni/Co mass ratio is also investigated, indicating that the high specific capacitance of the composite is contributed by Ni₃V₂O₈, while its excellent rate capability and cycle stability can be attributed to the Co₃V₂O₈ component.