Enhancing conductivity of Bi2O3 through 'Fe3+' doping for pseudocapacitor application

Binary metal oxides have emerged as pSromising materials for advanced electrochemical energy storage systems due to their superior performance characteristics. In this study, we focus on bismuth oxide (Bi2O3), a material renowned for its high theoretical capacity, wide potential range, and exceptional power density, as a potential candidate for supercapacitors. Iron doping was employed as a strategy to enhance its electrochemical performance and modulate the band gap, thereby improving conductivity and charge storage efficiency. Fe-doped bismuth oxide (Fe-Bi2O3) was synthesized via a solvothermal method with varying iron concentrations (2%, 4%, and 6%), followed by annealing. The pure and iron-doped bismuth oxide samples revealed a combination of monoclinic and cubic phases and a prominent micro-sheet architecture. The introduction of iron doping led to a noticeable reduction in the band gap, highlighting its role in fine-tuning the electronic properties for enhanced energy storage capabilities. The electrochemical evaluation highlighted the 4% Fe-Bi2O3 sample as the optimal composition, achieving a remarkable specific capacity of 904 F g(-1), a substantial improvement over 101 F g(-1) for pristine Bi2O3, at 1 A g(-1) in a 2 M KOH electrolyte. Moreover, this sample exhibited outstanding cyclic stability, retaining 104 F g(-1) after 2000 cycles at 10 A g(-1).