Design of a new nanocomposite based on Keggin-type [ZnW 12 O 40 ] 6– anionic cluster anchored on NiZn 2 O 4 ceramics as a promising material towards the electrocatalytic hydrogen storage

Abstract

While hydrogen is considered as a highly promising alternative fuel for energy production and consumption systems due to its clean-burning properties, its relatively low volumetric energy density has hindered its sorption abilities under ambient conditions. As a result, extensive research efforts have been dedicated to developing electrode materials with high capacity in order to address the increasing complexities arising from the energy crisis. Herein, a new nanocomposite was synthesized via the sol-gel method by immobilizing potassium salt of Keggin-type polyoxometalate ([ZnW12O40]6–) within the surface of NiZn2O4 ceramics. The assembled nanocomposite (ZnW12O40/NiZn2O4) was characterized by FT-IR, UV-vis, XRD, SEM, EDX, BET, and TGA-DTG methods. Furthermore, the electrochemical characteristics of the materials were examined using cyclic voltammogram (CV) and charge-discharge chronopotentiometry (CHP) techniques. Multiple factors affecting the hydrogen storage capacity, including current density (j), surface area of the copper foam, and the consequences of repeated cycles of hydrogen adsorption-desorption were evaluated. The initial cycle led to an impressive hydrogen discharge capability of 340 mAh/g, which subsequently increased to 900 mAh/g after 20 runs with a current density of 2 mA in 6.0 M KOH medium. The surface area and the electrocatalytic characteristics of the nanoparticles contribute to facilitate the formation of electrons and provide good diffusion channels for the movement of electrolyte ions throughout the charge-discharge procedure.