Green energy generation via water splitting by non-photocatalytic process based on Gd doped magnesium ferrite hydroelectric cells

Abstract

This study presents compelling empirical evidence that highlights the notable effect of increased defect concentration on the splitting of water molecules in MgGdxFe2-xO4 hydroelectric cells (HECs), which serve as a promising avenue for environmentally friendly electricity generation. The MgGdxFe2-xO4 (x = 0.00, 0.02, 0.06 and 0.10) series for eco-friendly electricity generation has been successfully synthesized using a facile sol-gel technique. These materials exhibit the characteristic spinel cubic structure with the Fd-3 m space group confirmed using Rietveld analysis of X-ray diffraction plots. A maximum strain of 7.49×10-3 was observed in the MgGd0.10Fe1.90O4, indicating the formation of a probable defective structure. Moreover, the X-ray density values decrease with increase in Gd concentration, suggesting an increase in porosity of the samples. Langmuir hysteresis curve follows a typical type IV pattern further consolidating the mesoscopic nature of the materials. Furthermore, the conclusive identification of defects, particularly oxygen vacancies, through Photoluminescence and X-ray Photoelectron Spectroscopic (XPS) studies, holds an utmost importance in facilitating the water dissociation process at room temperature by ferrites. Impedance spectroscopy has been employed to scrutinize the contribution of small polaron hopping-assisted ionic conduction to the observed improved current density. The maximum short circuit output current of 6.8, 10.1, and 13.4 mA was achieved for MgGd0.02Fe1.98O4 (GMF-1), MgGd0.06Fe1.94O4 (GMF-2) and MgGd0.10Fe1.90O4 (GMF-3) HECs, respectively. The corresponding open cell voltage values were found to be 0.85 V, 0.92 V and 0.98 V. Off-load peak power output was 5.78 mW, 9.29 mW, and 13.13 mW, respectively. The estimated Gibbs free energy values were -164.02, -177.53, and −189.11 kJ/mol. MgGdxFe2-xO4-based hydroelectric cells possess the advantages of being cost-effective and yielding eco-friendly by-products without reliance on photocatalytic activity, acid/alkali solutions, or electrolytes. The incorporation of Gadolinium (Gd) dopant not only enhances the hydroelectric current but also contributes to sustained current generation over extended periods. The extended operational lifespan of the cell positions it as an excellent candidate for practical applications