Gamma-Induced Cationic Inversion in Cobalt Ferrite for High-Performance Hydroelectric Cells

The development of next-generation energy materials is pivotal for addressing global energy demands and achieving sustainable, carbon-neutral power solutions. Hydroelectric cells (HECs), which generate clean energy via water dissociation, offer a promising pathway for energy generation. This study employs gamma irradiation as an effective defect-engineering approach to enhance the performance of cobalt ferrite (CoFe 2 O 4 )-based HECs. CoFe 2 O 4 was synthesized via a solid-state route and subjected to gamma doses of 0, 20, 50, 100, and 200 kGy. X-ray diffraction confirmed the cubic spinel phase, while irradiation reduced crystallite size and increased lattice strain and structural disorder, as evidenced by peak broadening, elevated Urbach energy, and high-resolution transmission electron microscopy observed defects. X-ray photoelectron spectroscopy revealed substantial cationic redox transitions (Fe 3+ → Fe 2+, Co 2+ → Co 3+ ) accompanied by marked rise in the oxygen vacancy concentration from 19% to 32% at 100 kGy. These irradiation-induced defects serve as active sites for water adsorption and dissociation, thereby boosting the ionic conductivity and accelerating electrochemical kinetics. Consequently, the offload current density and power density of the HECs improved nearly 3-fold, achieving 7.18 mA/cm 2 and 0.76 mW/cm 2, respectively. This study underscores gamma irradiation as a powerful strategy to tailor defect landscapes and cation valence states in CoFe 2 O 4 for sustainable green energy generation systems.