Improved Electrochemical Performance from Nano-Cobalt Oxide: Bifunctional Application in Energy Generation and Storage

Abstract

The bifunctional properties, supercapacitive and water splitting, of the electrodeposited nano-Co3O4 film grown on different substrates, namely, FTO, carbon paper, and carbon cloth, have been investigated. A comparative study shows that the underlying substrate, on which the nano-Co3O4 film is deposited, plays a role and affects the performance. A detailed electrochemical study carried out on the Co3O4@CC electrode reveals that the charge is stored at the electrode/electrolyte interface in the form of a redox state triggered by the faradaic reaction and thus provides a pseudocapacitive nature to the electrode by exhibiting a capacitance of 265 F/g at a current density of 2 A/g. Additionally, electrode's stability, coulombic efficiency, and capacitance retention were found to be excellent. In addition to the energy storage, electrically assisted water-splitting property has also been observed at the electrode surface for which the nano-Co3O4 electrodes act as catalysts to exhibit the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at the electrode/electrolyte interface. The overpotential for HER and OER has been measured to be 580 and 620 mV with their respective Tafel slope of 171 and 270 mV dec-1. Overall, the Co3O4@CC electrode was found to be the best-performing electrode for bifunctional application in water splitting and supercapacitive energy storage. © 2022 American Chemical Society.