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

Abstract

Summary 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.

Effect of Li+, Mg2+, and Al3+ Substitution on the Performance of Nickel Ferrite-Based Hydroelectric Cells

“…Shah et al enhanced the output short-circuit current of the SnO 2 HEC to a high value of 93 mA by doping antimony (Sb) in metallic form, which makes it a highly oxygen-deficient and reduced compound . We reported earlier the effect of synthesis temperature on the oxygen vacancies and short-circuit current of Li 0.3 Ni 0.4 Fe 2 O 4 and NiFe 2 O 4 . , …”

“…13 We reported earlier the effect of synthesis temperature on the oxygen vacancies and short-circuit current of Li 0.3 Ni 0.4 Fe 2 O 4 and NiFe 2 O 4 . 14,15 As per the literature review, SnO 2 and spinel ferrite-based HECs have shown promising results. 11,16,17 Spinel ferrite with a chemical formula of MFe 2 O 4 can be categorized into three categories: (i) normal, (ii) inverse, and (iii) mixed ferrite.…”

“…19−23 Ferrites have been studied for hydroelectric cell application in the past. 2,3,7,9,11,14,15,24 Lattice strain, porosity, and defects (oxygen vacancies) play a prominent role in water dissociation on the material's surface for hydroelectric cells. These defect centers provide sites for water adsorption and chemidissociation on the material's surface.…”

“…The hydroelectric cell has emerged in the past as a cost-effective green energy source to generate electric energy by nonphotocatalytic water molecule dissociation. Ferrites have shown wide application in the field of catalysis, water splitting, oxygen evolution reaction, hydrogen evolution reaction, supercapacitors, and many other fields. − Ferrites have been studied for hydroelectric cell application in the past. ,,,,,,, Lattice strain, porosity, and defects (oxygen vacancies) play a prominent role in water dissociation on the material’s surface for hydroelectric cells. These defect centers provide sites for water adsorption and chemidissociation on the material’s surface.…”

Enhanced Water Splitting by Strained Lithium-Substituted Nickel Ferrite Hydroelectric Cells

“…The HEC gives hope and a different perspective to work on it because it fulfills both the environmentally friendly criterion and the energy supply–demand for human well-being. Recently, a lot of research has been reported on the HEC. − Magnesium ferrite was the first material used for HEC application …”