Synthesis of Eco-Friendly Zn-Ni Bimetallic MOFs with Biodegradable Glycolic Acid Ligands for Enhanced Supercapacitor Performance and Hydrogen Evolution Reaction

Abstract 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 (2060 F/g) under a current density of 1.0 A/g at 70 oC. 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 (55 F/g) at a higher current density of 2.0 A/g. 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.