Enhanced Water Splitting by Strained Lithium-Substituted Nickel Ferrite Hydroelectric Cells
Sandeep Saini, K. L. Yadav, Jyoti Shah, R. K. Kotnala
Abstract
Hydroelectric cells (HECs) have received significant attention due to green and clean energy generation. In this work, we have developed HECs using porous, oxygen-deficient bare and lithium-substituted nickel ferrites. Monovalent lithium ions prefer to occupy octahedral sites of spinel ferrite and replace the Fe and Ni ions. Lithium ions induce the strain and defect in the spinel lattice, which acts as the reactive site for the adsorption and dissociation of water molecules. Porosity percentage and strain have been calculated from X-ray diffraction patterns and Williamson–Hall plots. Fourier transform infrared spectroscopy confirms the water adsorption on substituted ferrite samples. Raman spectroscopy and X-ray photoelectron spectroscopy have confirmed the increase in the number of defects with lithium substitution. The conductivity of lithium-substituted nickel ferrite HECs was observed by ac conductivity and Nyquist plots. The fabricated HECs based on Li-substituted nickel ferrite delivered high short circuit current and off-load peak power compared to a pure nickel ferrite-based HEC. A maximum short circuit current of 67 mA and open-circuit voltage of 0.94 volts have been obtained for a Li0.25Ni0.5Fe2.25O4-based HEC of 4.8 cm2 area. This enhancement in short circuit current is 2.7 times higher than that in the nickel ferrite-based HEC. A current density of 13 mA/cm2 generated by the nickel ferrite-based HEC is a significant value in order to surpass solar cells.