Metal-Organic Framework-Derived Ultra-Microporous Bismuth Oxide Synchronizing Energy Density and Stability in Symmetric Supercapacitors

Abstract

The development of bismuth oxide (Bi 2 O 3 ) for supercapacitors is hampered by its intrinsic poor electrical conductivity and structural instability. Herein, a metal-organic framework (MOF)derived strategy is presented to engineer ultra-microporous Bi 2 O 3 architectures with tailored electronic and structural properties. Through a solvothermal-calcination process using terephthalic acid, Bi 2 O 3 is transformed into a hierarchically porous structure with a high surface area of 117 m 2 g -1 , dominated by ultra-micropores (0.42 nm). This architecture facilitates efficient ion transport and redox kinetics, evidenced by a low charge-transfer resistance, achieving a specific capacitance of 1248 F g -1 at 0.5 A g -1 in a three-electrode configuration. When configured as a symmetric supercapacitor, the MOF-derived Bi 2 O 3 electrode delivers a specific capacitance of 1088 F g -1 , a high energy density of 288 Wh kg -1 , and a power density of 109 W kg -1 . The device exhibits high cyclic stability, retaining 75.3% of its initial capacitance over 10,000 cycles with a Coulombic efficiency of 81.4%. This work underscores the profound impact of MOF-derived ultramicroporosity in overcoming the limitations of metal oxides, paving the way for next-generation, long-lasting energy storage devices.