The morphology of NiCo₂O₄ can be controlled by changing the kinds of alkali source and the addition of NH₄F, influencing its electrochemical properties.

As the lightest structural metal material, magnesium alloys possess good casting properties, high electrical and thermal conductivity, high electromagnetic shielding, and excellent damping properties. With the increasing demand for lightweight, high-strength, and high-damping structural materials in aviation, automobiles, rail transit, and other industries with serious vibration and noise, damping magnesium alloy materials are becoming one of the important development directions of magnesium alloys. A comprehensive review of the progress in this field is conducive to the development of damping magnesium alloys. This review not only looks back on the traditional damping magnesium alloys represented by Mg-Zr alloys, Mg-Cu-Mn alloys, etc. but also introduces the new damping magnesium materials, such as magnesium matrix composites and porous magnesium. But up to now, there have still been some problems in the research of damping magnesium materials. The effect of spiral dislocation on damping is still unknown and needs to be studied; the contradiction between damping performance and mechanical properties still lacks a good balance method. In the future, the introduction of more diversified damping regulating methods, such as adding other elements and reinforcements, optimizing the manufacturing method of damping magnesium alloy, etc., to solve these issues, will be the development trend of damping magnesium materials.

Developing efficient and stable ORR catalysts for Mg-air batteries is crucial to enabling extensive applications. Herein, CuMnO ₂ nanoflakes were synthesized with a facile one-step hydrothermal way and applied as the cathode catalyst for Mg-air batteries. The ORR activities in alkaline and neutral electrolyte were then investigated. The half-wave potential has a minus variation of 22 mV after 5000 cycles, indicating the outstanding stability of the CuMnO ₂ . The electron transfer number of the CuMnO ₂ is 3.70 under neutral condition, which demonstrates that the reaction process of ORR is equivalent to the commercial Pt catalyst. Moreover, the primary Mg-air battery with CuMnO ₂ as the cathode catalyst was assembled and the discharge properties were tested. The open circuit voltage achieved was 1.78 V and the operating voltage remained about 1.36 V after 22 h operation at 1.0 mA·cm ⁻² . It is evident that the CuMnO ₂ nanoflake is an effective catalyst to accelerate the reaction rate of ORR process in Mg-air battery. This work provides a novel approach for the subsequent exploration of non-noble metal catalysts for Mg-air batteries.