Scalable Synthesis of Layered Bismuth Germanate (Bi₁₂GeO₂₀) for Supercapacitors and Sodium ion Battery Applications

Bismuth-based semiconductors have attracted significant attention in rechargeable batteries and supercapacitor devices. In this study, layered structured bismuth germanate (Bi₁₂GeO₂₀) was synthesized using hexamine as a surfactant, at 850 °C, and utilized as electro-active material for supercapacitor and sodium ion (NaB) storage applications. The physical characterization of the prepared Bi₁₂GeO₂₀ was studied with various characterization and microscopic analyses such as XRD, FT-IR, FESEM with EDS, HRTEM, and XPS analysis. The XRD analysis exposed the successful formation of a highly crystalline sillenite phase of Bi₁₂GeO₂₀. The surface morphology analysis FE-SEM and HR-TEM revealed the effective construction of the 2D layered structure of Bi₁₂GeO₂₀. The EDS results profound that uniform distribution of the Bi, Ge, and O elements with good elemental stoichiometry. The supercapacitor properties of the prepared Bi₁₂GeO₂₀ were evaluated with the help of three electrode method using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance (EIS) techniques in the aqueous solution of 3.0 M KOH. The prepared Bi₁₂GeO₂₀ architecture shows a higher specific capacitance of 355 F g⁻¹, with a current density of 1 A g⁻¹. Finally, the sodium-ion storage capacity of Bi₁₂GeO₂₀ was evaluated using a coin cell-type electrode. The as-synthesized Bi₁₂GeO₂₀ material was utilized as an anode for Na ion storage and demonstrated a high specific capacity of 740 mAh g⁻¹ at 0.1 C rate. With these appreciable electrochemical performances, the single component Bi₁₂GeO₂₀ holds an ideal alternative electrode material to develop high-performance power and energy storage devices.