Electrochemical Hydrogen Storage by a New Nanocomposite AuW₁₁Ni@HKUST-1@MOF-5 Multi-Component Composite as an Innovative Cathode Material

To meet the global energy demand, research efforts have been focused on enhancing electrode materials to address the challenges associated with the energy crisis. In this regard, a novel ternary-component hybrid nanocomposite-based host–guest material was prepared by encapsulating potassium salt of nickelII-coordinated gold(III) dodecatungstate (K6[AuW11NiO39]·6H2O, abbreviated as AuW11Ni) in the scaffold of nonisostructural metal–organic framework (MOF) pairs, including HKUST-1 and MOF-5. After characterization of the corresponding inorganic–organic hybrid material (AuW11Ni@HKUST-1@MOF-5) by various techniques, the as-prepared nanocomposite served as a high-capacity electrode material for electrochemical hydrogen storage application. The electrochemical properties were analyzed via cyclic voltammetry and charge–discharge chronopotentiometry (CP) methods at a scan rate of 50 mV s–1. Various parameters influencing the H2 storage capacity were examined, including the surface area of the Cu foam, current (mA), and Coulombic efficiency. The initial cycle of the AuW11Ni@HKUST-1@MOF-5 displayed a remarkable hydrogen discharge capacity of 2250 mAh g–1 using an optimal current of ±1.5 mA in 6.0 M KOH, which subsequently increased to 2990 mA h g–1 following 20 cycles, demonstrating a Coulombic efficiency of 80.81%. High capacity of the AuW11Ni@HKUST-1@MOF-5 suggests that developing this composite is a feasible approach to design high energy cathode materials for the hydrogen storage process.