Electrosynthesized Fe‐based, Cu‐based and Fe‐Cu Metal‐Organic Framework Systems for Supercapacitor Applications

ABSTRACT A novel electrochemical method was successfully developed for the synthesis of monometallic MIL‐100(Fe), HKUST‐1 and Fe‐Cu metal‐organic framework (MOF) systems under mild conditions and short reaction times. X‐ray diffraction confirmed the successful formation of the parent frameworks, showing strong agreement with simulated patterns from the literature. Structural analysis of the Fe‐Cu MOF systems revealed the coexistence of Fe‐based and Cu‐based MOF phases, forming physical phase mixtures. Textural characterisation by N 2 adsorption‐desorption measurements revealed high surface areas of 1,044 m 2 ·g −1 for MIL‐100(Fe), 781 m 2 ·g −1 for HKUST‐1 and up to 800 m 2 ·g −1 for selected Fe‐Cu MOF systems. The electrochemical performance of MIL‐100(Fe), HKUST‐1 and Fe‐Cu(3.75/15) system was evaluated using galvanostatic charge‐discharge and cyclic voltammetry in a three‐electrode configuration with conductive catalytic inks. All materials displayed hybrid supercapacitor behaviour, combining electric double‐layer capacitance and pseudocapacitive contributions. The Fe‐Cu MOF system (Fe‐Cu(3.75/15)) demonstrated enhanced electrochemical performance, achieving a specific capacitance of 1,073 F·g −1 , an energy density of 205 Wh·kg −1 at 1 A·g −1 , and a power density of 3,632 W·kg −1 at 5 A·g −1 . The improved performance is attributed to the coexistence of Fe‐ and Cu‐based MOF phases, which promote complementary redox activity and charge storage mechanisms. These results highlight the potential of electrochemically synthesised MOF phase mixtures as promising materials for high‐performance supercapacitor applications.