Improvement of the electrochemical performance of Bi₂O₃ by electron beam irradiation

The method of preparation is a critical factor affecting the structure and properties of Bi₂O₃ material. In this work, Bi₂O₃ was synthesized through calcination (denoted as Bi₂O₃–C) and hydrothermal methods (denoted as Bi₂O₃–H), utilizing bismuth-based metal–organic framework (Bi–MOF) as the precursor. As an electrode material for supercapacitors, Bi₂O₃–H demonstrated outstanding rate performance (515 F g⁻¹ at 50 A g⁻¹) and remarkable cycle stability (74% retention after 4000 cycles). Subsequently, the Bi₂O₃-H underwent further processing through electron beam irradiation (EBI), resulting in a sample designated as Bi₂O₃–I. Following EBI treatment, the crystalline characteristics of Bi₂O₃–I and the concentration of oxygen vacancies (OVs) exhibited a significant improvement, thereby augmenting the material's conductivity. Because the positively charged OVs can quickly attract OH⁻ from the electrolyte to the electrode surface, thereby accelerating the REDOX reaction, the current control mechanism of Bi₂O₃–I is partially derived from a surface-controlled pseudo-capacitance process. The irradiated Bi₂O₃-I electrode demonstrated superior capacitance (990 F⁻¹ at 2 A g⁻¹), enhanced rate performance (585 F⁻¹ at 50 A g⁻¹), and remarkable cycling stability (83% retention after 4000 cycles).