Construction of 2D MOF nanosheets with missing-linker defects for enhanced supercapacitor performance

Abstract

Metal-Organic Frameworks (MOFs) are highly promising as electrode materials for supercapacitor development due to their large specific surface areas and tunable pore structures. Nevertheless, the intrinsic poor conductivity and suboptimal electrochemical performance of MOFs present substantial challenges. Traditional pyrolysis methods often compromise the inherent characteristics of MOFs. Consequently, a reasonable design of the original MOFs is a promising approach to enhancing its performance. This study commenced with pristine two-dimensional (2D) Ni-BTC (BTC = Trimesic acid) and improved their electrical conductivity and active site accessibility by embedding isophthalic acid (IPA) as missing linkers, resulting in defective Ni-BTC/IPA-x. The physicochemical properties of Ni-BTC/IPA were systematically characterized. The results indicate that defects effectively modulate the electronic structure of the metal center, pore structures, and specific surface areas of MOFs, which is conducive to improving supercapacitor performance. Electrochemical measurements reveal that Ni-BTC/IPA-3 exhibits an exceptional specific capacity of 1209 F g−1 at 0.5 A g−1, demonstrating a rate performance of 70.8 %. Furthermore, hybrid supercapacitor (HSC) devices, incorporating the Ni-BTC/IPA-3, possess an energy density of 30 Wh kg−1 at a power density of 1775.8 W kg−1. These HSC devices successfully power multi-colored light-emitting diodes (LEDs), highlighting their significant potential for practical energy storage applications.