Synergistic engineering and sintering-induced tuning of Al Sn co-doped Zn/Co ferrites for integrated hydroelectric and supercapacitive energy systems

The growing demand for sustainable energy technologies has prompted intensive research into multifunctional materials capable of both energy generation and storage. In this study, nanostructured spinel ferrites ZnAl 0.1 Sn 0.1 Fe 1.8 O 4 (ZASFO) and CoAl 0.1 Sn 0.1 Fe 1.8 O 4 (CASFO) were synthesized via a sol–gel auto-combustion method and sintered at 800 °C, 1000 °C, and 1200 °C to investigate their structural, electrochemical, and hydroelectric properties. Structural analyses using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed single-phase cubic spinel formation with thermally induced grain growth, cation redistribution, and strain relaxation. Electrochemical performance was assessed via cyclic voltammetry and galvanostatic charge–discharge, revealing superior pseudocapacitive behavior in CASFO sample sintered at 1000 °C (CASFO 1000 ), driven by Co 2+ /Co 3+ and Fe 2+ /Fe 3+ redox transitions, high conductivity, and optimized mesoporosity. CASFO 1000 achieved a specific capacitance of 756.57 F/g at 1 mV/s and retained >90 % capacity after prolonged cycling. Concurrently, hydroelectric cell evaluations demonstrated enhanced water dissociation and energy conversion in CASFO 1000 , yielding an open-cell voltage of 1.05 V and maximum power output of 31.74 mW. These findings underscore the synergistic role of Co substitution, Al and Sn co-doping, and optimized sintering in tailoring spinel ferrite frameworks for integrated green energy applications. This study offers a comprehensive pathway for the design of high-performance oxide-based materials for concurrent energy harvesting and storage systems. • Al/Sn co-doping and sintering temperature optimization enhances the electrochemical and hydroelectric performance of Zn-based ferrites. • CoAl₀.₁Sn₀.₁Fe₁.₈O₄ sintered at 1000 °C delivers 756.57 F/g at 1 mV/s and a hydroelectric power of 31.74 mW. • Sintering at 1000°C optimizes grain connectivity, reduces charge transfer resistance, and enhances redox activity (Fe 2+ /Fe 3+ and Co 2+ /Co 3+ ). • The ferrite layer facilitates proton conduction and water splitting, enabling spontaneous electricity generation in a hydroelectric cell. • A comprehensive mechanism highlights how dopants, sintering, and charge dynamics collectively drive hybrid energy conversion.