Electrical energy of the order of 24 W/m2 from water splitting using nickel oxide: Effect of synthesis process on power output

Abstract

Electricity production from metal oxides using the water-splitting phenomenon is an innovative method that came into existence recently. Still, a lot of research is going on to find optimal metal oxide which can produce maximum electrical energy under standard room conditions. In the present work, Nickel oxide has been explored for the same using different synthesis techniques viz. solid-state method, sol–gel method, and hydrothermal method to compare their respective efficiencies. XRD study reveals the crystalline nature and crystallite size of the material synthesized by three methods. A minimum crystallite size of 11 nm is observed when synthesized by hydrothermal technique. BET confirms the specific surface area of NiO to be 11.58, 20.32, and 47.83 m2/g prepared by the solid-state method, sol–gel method, and hydrothermal method respectively. Small-type cubical-type morphology is also observed in the FESEM study of NiO. UV–visible spectrometry reveals band gap of the material increase from 4.5 to 5 eV when we shift from the solid-state method to the hydrothermal method. NiO synthesized using the hydrothermal method has a smaller crystallite size and more surface areas and porosity giving a peak power of 12.36 mW with short circuit current (Isc) of 12 mA and open circuit voltage (Voc) of 1.03 V. Three such cells connected in series are capable of glowing an LED.

Keywords

• Water splitting
• Nickel oxide
• Renewable energy
• Green energy