Significant role of defect‐induced surface energy in water splitting to generate electricity by nickel ferrite hydroelectric cell

Abstract

Hydroelectric cell (HEC) is a magnificent device that produces environment friendly, clean and green energy using water only. In this device, electrical power is generated by splitting water into hydronium and hydroxide ions at room temperature without applying any external energy. The water splitting is carried out by oxygen-deficient and nanoporous nickel ferrite (NFO) via chemidissociation followed by physidissociation of water molecules wherein, the dissociated ions are collected by zinc anode and inert silver cathode of HEC. The surface energy of metal oxide/ferrite plays a crucial role in attracting and dissociating water molecules. Differential scanning calorimetry analysis confirms the role of sintering temperatures to create oxygen vacancies on the surface of NFO. Also, the presence of oxygen vacancies in the sintered samples has been confirmed by X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. A lower enthalpy of desorption 69.31 kJ/mol in NFO-1 (950°C) has been calculated compared to 80.46 kJ/mol for NFO-2 (1050°C). It confirms that more water is adsorbed on NFO-1 which implies lesser energy is required for water chemidissociation. The V–I polarisation curve of NFO-based HECs records a maximum current output of 15.3 mA for NFO-1 and 9.28 mA for NFO-2. In the present study, the role of oxygen vacancy-induced surface energy has been found to be a key parameter in water chemidissociation to deliver higher current in HECs. Thus, the present work is a unique revolutionary work to produce green electricity by monitoring defects in NFO among the available other techniques.