Nanoarchitectonics with redox active site modulation in bimetallic MIL-125(Ti, Mn) MOF for enhanced supercapacitor performance

Metal-organic frameworks (MOFs) involving dual transition metals have recently gained prominence as promising materials in energy storage applications because of their redox activity sites and unique structural architecture. Herein, we present a facile one-pot solvothermal strategy for the design and optimization of bimetallic Mn-incorporated titanium-based metal-organic frameworks (MIL-125(Ti)) MOFs using benzene-1,4-dicarboxylic acid as a coordinating linker for asymmetric supercapacitors. A more distinct structure that incorporates spindle morphology covered with flake-like sheets allows for the interaction between active sites and electrolyte ions and modulates redox active sites for enhanced electrochemical performance. As such, the optimized MIL-125(Ti)-Mn-2 electrode demonstrates a high specific capacity of 137.2 mAhg-1 at 1 A g–1 and a capacity retention of more than 76.3% after 5,000 cycles. In addition, the asymmetric device fabricated using Mn-MIL-125(Ti)-2 and peanut shell-derived activated carbon affords a high specific energy of 22.74 Wh kg–1 at a specific power of 996 W kg–1, and an outstanding stability of 71.2% at 10 Ag-1 over 10,000 charge-discharge cycles. This one-pot incorporation strategy offers a novel strategy to modulate the structure of MIL-125(Ti) via Mn2+ doping and used as MOF-based electrode materials for enhanced supercapacitor performance.