Abstract
This study presents a novel metal organic framework (MOF-199) based composites synthesized under two conditions: room temperature (RCMBF) and hydrothermal (HCMBF). Initially, MOF-199 was doped with barium, followed by fluorine-doped titanium dioxide (F-TiO₂) to form the final composites. These materials were combined with activated carbon (AC) to fabricate asymmetric supercapacitor cells, enhancing the energy storage performance. Dual doping improved the ionic conductivity and electrochemical behavior. Structural and morphological analysis, such as scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) confirmed the octahedral MOF-199 morphology in the pristine MOFs and composite coarseness. X-ray diffraction (XRD) revealed sharp 2θ peaks, indicating high crystallinity. Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) revealed strong interactions between the dopants and MOF-199, confirming their thermal and chemical stability. Brunauer-Emmett-Teller (BET) analysis showed progressive reduction in surface area due to layer-by-layer stacking. Xray photoelectron spectroscopy (XPS) revealed excellent interactions between dopants and MOF framework. Electrochemical tests revealed that in a three-electrode system, the RCMBF achieved a specific capacitance of 67 F g⁻¹, whereas the HCMBF reached 57 F g⁻¹. In a two-electrode system with AC, RCMBF delivered 123 F g⁻¹, and the HCMBF delivered 68 F g⁻¹ via cyclic voltammetry (CV). Electrochemical impedance spectroscopy (EIS) analysis revealed that the RCMBF electrode had less resistance than the HCMBF electrode. Galvanostatic charge discharge (GCD) tests at 0.07 mA g⁻¹ revealed that the RCMBF/AC achieved values of energy and power densities of 1.5 Wh kg⁻¹ and 126 kW kg⁻¹, respectively. At a current density of 0.02 mA g⁻¹, HCMBF/AC yielded 1.8 Wh kg⁻¹ and 45 kW kg⁻¹. At 10,000 cycles, the RCMBF/AC system demonstrated 79% retention, whereas the HCMBF/AC system showed 61% retention. The columbic efficiencies were 94% (RCMBF) and 83% (HCMBF) respectively. These results demonstrate the potential of Ba/F-TiO₂-doped MOF-199 composites for high-performance, eco-friendly supercapacitor applications.