Potential electrochemical hydrogen storage in nickel and cobalt nanoparticles-induced zirconia-graphene nanocomposite

Abstract

Green fuels which are sustainable in nature are becoming a reliable energy source in the era of climatic concerns. Hydrogen, a renewable clean energy carrier supplies energy three times more than that of conventional energy sources. Thus, efficient methods are developed to store hydrogen in a safe and cost-effective way. Synthesis of economical and environmental friendly nanomaterials that can be used for hydrogen storage has paramount importance in research field. Nanocomposites with good surface area and porosity emerge as effective materials in the field of sustainable hydrogen storage. We synthesized nanocomposites having metal, metal oxide and carbon content in them to explore their hydrogen storage capacity (HSC). Nickel zirconia reduced graphene oxide (Ni–ZrO₂–rGO), and cobalt zirconia-reduced graphene oxide (Co–ZrO₂–rGO) were synthesized hydrothermally. The confirmation of their structure, composition, and morphology were done by various characterizations. The surface area calculations of nanocomposites were carried out by nitrogen (N₂) adsorption–desorption measurements. Thereafter, these samples were coated onto nickel foam and their electrochemical studies were carried out in 6 M KOH electrolyte to evaluate their HSC. The discharge capacity for Ni–ZrO₂–rGO was calculated to be 416.12 mAhg⁻¹ (1.54 wt%) and 291.38 mAhg⁻¹ (1.07 wt%) for Co–ZrO₂–rGO. These nanocomposite having all three metal, ceramic and carbon components influence HSC in a considerable way. All constituents have significant influence, as the metal part alters the electrocatalytic properties, zirconia impacts the crystalline structure and porosity is varied due to properties of graphene.