Synthesis of Eco-friendly Zn-Ni bimetallic MOFs with biodegradable glycolic acid ligands for enhanced supercapacitor performance and hydrogen evolution reaction

Electrochemical technologies like supercapacitors and water-splitting electrolysis are gaining traction due to their impressive efficiency in both energy storage and generation. A hydrothermal technique was employed to synthesize a metal-organic framework (MOF) containing zinc and nickel. Glycolic acid (GA), a naturally occurring biodegradable ligand, was utilized to explore its potential for incorporation into the MOF heterostructure. The ZnNi-MOF (GA) composites showed a notable specific capacity of 1648 C g⁻¹ (2060 F/g) under a current density of 1.0 A g⁻¹ at 70 °C. The study investigated a supercapacitor system design where a combination of polyaniline-doped activated carbon was used for the negative electrode and a zinc-nickel metal-organic framework (GA) was used for the positive electrode. The synthesized ZnNi-MOF (GA)//AC energy storage device demonstrated a specific capacity of 110 C g⁻¹ (55 F g⁻¹) at a higher current density of 2.0 A g⁻¹. The recyclability and stability of device (ZnNi-MOF (GA)//AC) were evaluated using 10000 charge-discharge cycles, yielding an 86% capacity retention. The ZnNi-MOF (GA) composite displayed outstanding catalytic ability in the hydrogen evolution reaction (HER) in comparison to other tested materials, achieving the lowest Tafel slope of 42.79 mV/dec. The findings of our research suggest that ZnNi-MOF (GA) exhibits desirable characteristics that make it a promising material for electrodes in the applications of supercapattery and HER.