Green synthesis of [formula omitted]2[formula omitted]4[formula omitted] nanoparticles as effective electrode materials for electrochemical hydrogen and energy storage: A comparative study.

Molecular hydrogen is a promising energy carrier and the best potential alternative for environment-damaging fossil fuels. Hydrogen as a secondary clean energy can lead to the development of fuel cell technology. Hydrogen transportation is highly costly due to its low volumetric energy density at ambient temperature and pressure. However, reactive hydrogen can be electrochemically generated in the solid state and occurs either as a surface-adsorbed or lattice-settled species. Herein, the mesoporous structures of LiMn 2 O 4 and NiMn 2 O 4 were prepared by using Aleo Vera extract as a complexing agent. The samples were characterized by various techniques to determine their crystal structures, surface morphology, and porosity. Electrochemical hydrogen storage abilities and the specific capacitance values of as-prepared mixed metal manganese oxides were measured in the 2 M KOH electrolyte solution. The results showed that LiMn 2 O 4 and NiMn 2 O 4 nanoparticles have an excellent specific capacitance of 783 and 552 Fg-1, respectively. The maximum discharge capacities of LiMn 2 O 4 and NiMn 2 O 4 nanoparticles were obtained to be 3605 and 1501 mAh/g after 11 cycles, respectively. The higher and excellent discharge capacity of LiMn 2 O 4 can partially be ascribed to its higher porosity. [Display omitted] • LiMn 2 O 4 and NiMn 2 O 4 nanoparticles were produced using a green method. • The crystalline texture, morphology, and porosity support hydrogen storage abilities. • The discharge capacity of the LiMn 2 O 4 and NiMn 2 O 4 nanoparticles were obtained 3605 and 1501 mAhg−1, respectively. • Promising materials for electrochemical hydrogen storage. [ABSTRACT FROM AUTHOR]