A novel arrangement of active and ultra-stable electrocatalyst based on iron/nickel/cobalt oxy/hydroxides for continuous oxygen evolution from alkaline seawater splitting

Abstract

This research offers novel ideas for development a new class of materials with enhanced OER kinetics utilizing an easy electrochemical deposition technique. Here, the Ti/CoNiyOx/FeOOH electrocatalyst was prepared in two steps. First, CoNiyOx thin film was anodically electrodeposited on an activated titanium substrate. Then iron oxyhydroxide (FeOOH) nanosheets were cathodically electrodeposited on the first layer. The properties of this electrocatalyst was evaluated and compared with some monolayer electrocatalysts using field emission scanning electron microscopy (FE-SEM), Raman, energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical methods. The Ti/CoNiyOx/FeOOH electrode requires an overpotential less than 330 mV at 100 mA/cm2 with Tafel constant of only 23.7 mV/dec for OER. The Ti/CoNiyOx/FeOOH electrode delivered long-term electrochemical stability in a solution containing corrosive chloride ions for more than 90 h at a constant current density of 100 mA/cm2 (with less than 9 % potential increase). Overall seawater splitting using the synthesized Ti/CoNiyOx/FeOOH electrode was performed at a current density of 100 mA/cm2 by a voltage as low as 1.58 V. The exceptional activity was ascribed to the synergistic effects of high electrochemical active sites and appropriate charge transfer ability found in CoNiyOx/FeOOH junction.