In Situ Rapid Formation of a Nickel–Iron-Based Electrocatalyst for Water Oxidation

Abstract

If an oxygen evolution reaction (OER) catalyst is expected to be more durable, especially under conditions of thin-layer catalysts or strong gas evolution, it will ideally function in a self-repair mode. In earlier studies, the electrochemical fabrications of Ni–Fe oxide catalysts were exclusively carried out by cathodic reduction of Ni(II) and Fe(III,II) in an individual solution that is different from the alkaline media commonly used for the OER. The procedure does not suggest that the dissolution/corrosion of the film catalysts could be countered by continual catalyst formation during the OER. Herein, we report a highly active NiFeOx catalyst by in situ rapid (3–15 min) anodic deposition of Ni(II) and Fe(III,II) in concentrated carbonate solution. At a transparent indium tin oxide (ITO) electrode, the conformal deposition of NiFeOx (7–11-atom layer) results in a very low optical loss (5–8%) with activity comparable to that of other planar NiFeOx films. Extension to a 3D nickel foam produces a hierarchi...