Enhanced ionic diffusion in a gold-augmented binary metal–organic framework composite with zirconium oxide for asymmetric supercapacitors and monosodium glutamate (MSG) detection

Layered intercalation compounds of Au-doped ZnCo-MOF/ZrO₂ nanoflakes were synthesized directly via a wet electrochemical process, with Au ions spontaneously integrating into the ZnCo-MOF interlayers. In a three-electrode setup, the Au@ZnCo-MOF/ZrO₂ can deliver a maximum of 1162.5 C/g at 1.5 A/g current density. The synthesized Au@ZnCo-MOF/ZrO₂-based supercapacitors demonstrate significantly faster ionic diffusion and pronounced redox peaks due to gold nanoparticles (Au NPs) and high ionic diffusion from the MOF and ZrO₂ components, achieving energy densities up to 63.77 Wh/kg and capacitances exceeding 287 C/g in an aqueous KOH electrolyte, outperforming traditional supercapacitors. The free-standing electrode structure and optimal crystal arrangement of the Au@ZnCo-MOF/ZrO₂ nanoflake electrodes contribute to exceptional electrochemical stability, retaining 99.9% of capacitance after 10,000 cycles. Additionally, the pre-intercalation effect was investigated to elucidate the enhanced electrochemical performance. This research shows that appropriate pre-intercalation can effectively improve the diffusion of electrolyte cations and overall electrochemical performance of layered oxides. Also, the Au@ZnCo-MOF/ZrO₂ electrode material was used to detect the monosodium glutamate. The resulting nanoflakes are promising materials for achieving high energy and power density hybrid supercapacitors.