Interfacial Engineering FeOOH/CoO Nanoneedle Array for Efficient Overall Water Splitting Driven by Solar Energy.

Interface engineering has been applied as an effective strategy to boost the electrocatalytic performance because of the strong coupling and synergistic effects between individual components. Here, we engineered vertically aligned FeOOH/CoO nanoneedle array with a synergistic interface between FeOOH and CoO on Ni foam (NF) by a simple impregnation method. The synthesized FeOOH/CoO exhibits outstanding electrocatalytic activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. For the overall water splitting, the bifunctional FeOOH/CoO nanoneedle catalyst requires only a cell voltage of 1.58 V to achieve a current density of 10 mA cm-2 , which is much lower than that required for IrO2 //Pt/C (1.68 V). The FeOOH/CoO catalyst has been successfully applied for solar cell-driven water electrolysis, revealing its great potential for commercial hydrogen production and solar energy storage.