Fine-tuning interconnected leaf-like architecture of Co-MOFs by varying linker concentrations for solid-state supercapacitors

Metal Organic Frameworks (MOFs) have risen as potential contenders for applications in supercapacitors (SCs) owing to their tunable porosity and surface chemistry. In this article, we synthesized Co-MOFs electrodes via Reaction Diffusion Framework approach, employing different linker concentrations, namely 0.7 M (CMA), 0.8 M (CMB), 0.9 M (CMC), and 1 M (CMD). The primary focus of this article lies in fine-tuning the concentration of the linker to optimize the synthesis of Co-MOFs, along with investigating how this optimization enhances their performance in an electrochemical study. Structural, morphological, and compositional studies have been con-ducted on Co-MOFs electrodes. Morphological studies unveiled CMB electrode exhibited a high interconnected leaf-like structure which enables high structural stability, low resistance, quick ion diffusion, and efficient charge-transfer in SCs than other electrodes. While the X-ray Photoelectron Spectroscopy analysis confirmed that the Co 2p exhibited an oxidation state of + 2. The electrochemical results demonstrated a direct correlation between linker concentration and the resultant leaf-like architecture. Specifically, the CMB exhibited high SCs performance, including a specific capacity (Csp) of 66 mAh/g and a specific capacitance (Cs) of 597 F/g at 5 mV/ s, maintaining an impressive cyclic stability of 80 % over 3000th cycles at 100 mV/s. Additionally, it achieved a good energy density (Ed) of 11.14 Wh/kg and power density (Pd) of 4000 W/kg at 4 mA/cm2. Furthermore, the solid-state device was fabricated and evaluated for its practical application in SCs. This device achieved higher Cs of 49 F/g at 10 mV/s, along with an 82 % retention rate over 2000 cycles at 15 mA. Moreover, this device attained a good Ed of 3.56 Wh/kg and Pd of 2266 W/kg at 4 mA. These findings manifested the significance of tailoring the morphology of Co-MOFs through optimal linker concentration for achieving high-performance solid-state SCs.