Base-Free Synthesis of Copper-Based Metal–Organic Frameworks Functionalized with Reduced Graphene Oxide for Enhanced Glucose Sensing and Supercapacitive Performance

A copper-based metal–organic framework (Cu-MOF) was synthesized via a wet chemical process, where Cu2+ ions coordinate with four imidazole ligands. This base-free deprotonation of pyrrolic nitrogen enabled Cu–N bond formation, producing the Cu-MOF framework. Functionalization with reduced graphene oxide (rGO) through covalent bonding enhanced both glucose sensitivity and supercapacitive performance. The Cu-MOF/rGO composite exhibited superior electrochemical performance, attributed to the catalytic activity of copper centers (Cu–N4) and the conductive matrix of rGO. The Cu-MOF component facilitates glucose oxidation by providing redox-active sites, while rGO ensures rapid charge transfer, leading to enriched sensitivity and a low detection limit. The composite displayed strong anti-interference capabilities, maintaining a steady response even among conventional interferents. This combination significantly enhanced both glucose adsorption and electron mobility, resulting in a spectacular sensitivity of 4036 μA mM–1 cm–2 with a limit of detection of 0.4 μM and a reliable specific capacitance of 287 F g–1.