CNT Interwoven Cu-MOF: A Synergistic Electrochemical Approach for Solid-State Supercapacitor and Hydrogen Evolution Reaction

Considering climate issues resulting from the burning of fossil fuels, the synthesis of cost-effective extensive electrodes for electrochemical energy storage and green hydrogen generation is one of the frontier research areas to sustainably meet current energy demand. Herein, a facile synthesis of a novel composite material (MC) consisting of copper-based metal–organic frameworks (Cu-MOFs) (M) interwoven with carbon nanotubes (CNTs) (C). The MC composite has been designed for bifunctional application as a high-performance solid-state supercapacitor electrode and for catalyzing hydrogen evolution reaction (HER). The Cu-MOF (M) is synthesized using a solvothermal technique, which, upon simple ultrasonication with activated CNTs, affords the Cu-MOF/CNT composite (MC). The coordinative interactions between carboxylate groups of CNTs with Cu (II) centers of Cu-MOF ensure a firm anchorage of two components, leading to a robust composite. Cu-MOF (M), with a suitable channel structure, offers a large number of accessible redox-active centers, while CNTs (C) provide a conductive network throughout the composite, enabling efficient charge transport and improved electrical conductivity. The calculated specific capacitance of the MC composite shows a value of 348.62 Fg–1 at 1 Ag–1 with a high-rate capability. Furthermore, to enhance practical usability, a symmetrical device has been constructed, achieving an energy density of 27.7 Wh kg–1 and a power density of 1.64 kW kg–1. The observed retention in capacitance is 90.15% after 10000 cycles. Moreover, the MC composite exhibited remarkable electrocatalytic activity for the HER, demonstrating an overpotential of 192 mV vs RHE at 10 mA cm–2, along with a Tafel slope of 129 mV dec–1. The dual functionality of the Cu-MOF (M) interwoven CNT (MC) composite as a high-performance solid-state supercapacitor and an efficient electrocatalyst for HER opens up opportunities for integrated energy storage and conversion devices.