Hollow Opening Morphology Engineering and Fe/Cu Doping for High Performance MOF Electrode Materials

As the demand for efficient energy storage solutions continues to rise, metal-organic frameworks (MOFs) have gained significant attention as potential electrode materials for supercapacitors. Herein, Ni-MOFs with uniform particle size and stable hawthorn-shaped hollow structures were controllably synthesized via the emulsion interfacial reaction and solvothermal methods. The electrochemical performances of both the undoped and Cu/Fe-doped samples as supercapacitor electrode materials were thoroughly investigated. The introduction of Fe and Cu introduced additional pore architectures and active sites, boosting charge transfer, ion diffusion, and pseudocapacitive behavior. Among the samples, Fe-Ni-MOF possessed the best mass capacitance, reaching 613 C g^-1 (1226 F g^-1) at 0.8 A g^-1. Both doped samples were further tested in asymmetric supercapacitor devices with Fe-Ni-MOF//AC exhibiting the best energy density of 34.75 Wh kg^-1 at a power density of 160 W kg^-1. This study advances the design and optimization of MOFs for supercapacitors, offering a potential candidate for practical electrode material development.