A bimetallic Fe–Mg MOF with a dual role as an electrode in asymmetric supercapacitors and an efficient electrocatalyst for hydrogen evolution reaction (HER)

Abstract

In this work, a novel bimetallic Fe–Mg/MOF was synthesized through a cost-effective and rapid hydrothermal process. The structure, morphology, and composition were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy. Further, the Brunauer–Emmett–Teller (BET) measurement showed a 324 m² g⁻¹ surface area for Fe–Mg/MOF. The Fe–Mg/MOF achieved 1825 C g⁻¹ capacity at 1.2 A g⁻¹ current density, which is higher than simple Fe-MOF (1144 C g⁻¹) and Mg-MOF (1401 C g⁻¹). To assess the long-term stability of the asymmetric device, the bimetallic MOF supercapattery underwent 1000 charge/discharge cycles and retained 85% of its initial capacity. The energy and power densities were calculated to be 57 W h kg⁻¹ and 2393 W kg⁻¹, respectively. Additionally, Fe–Mg/MOF showed superior electrocatalytic performance in hydrogen evolution reaction (HER) by demonstrating a smaller Tafel slope of 51.43 mV dec⁻¹. Our research lays the foundation for enhancing the efficiency of energy storage technologies, paving the way for more sustainable and robust energy solutions.