Engineering Coordination-Modulated Binary Nickel Cobalt MOF Nanoarchitectures for Enhanced Supercapacitor Performance.

Abstract

A strategy focused on modulating the coordination environment facilitated the development of an optimized NiCo metal-organic framework (MOF). This advancement has directly contributed to a higher capacitance and improved efficiency for supercapacitor applications. The present study investigates how coordination modulation (CM) affects deprotonation of the organic linker and nucleation, as well as their subsequent influence on the electrochemical performance of bimetallic NiCo MOFs. This CM strategy resulted in the formation of NiCo MOFs with different pH levels at various concentrations, resulting in distinct morphologies, further highlighting the critical role that pH plays in determining the structural, textural, surface charge, and electrochemical properties of the materials. These outcomes emphasize the significance of CM in the pH-induced surface charge effect for supercapacitors. Notably, the NiCo MOFs synthesized at pH 6.0 exhibited an extraordinary specific capacitance of 576.4 F/g at a current density of 1 A/g, along with energy and power densities of 24.2 Wh/Kg and 275 W/kg, respectively. Furthermore, the asymmetric device composed of pH 6.0 NiCo MOF and activated carbon achieved a specific capacitance of 61.03 F/g with an energy density of 20.4 Wh/kg, a Coulombic efficiency of 92.75%, and capacity retention of 87.50% after 2500 cycles. Armed with the knowledge of the CM strategy, this article successfully elucidated the effect of CM and pH on bimetallic NiCo MOFs, pinpointing that NiCo MOF at pH 6.0 is a potential candidate by all beneficial means.