Intercalation of Cobalt into the Interlayer of Birnessite Improves Oxygen Evolution Catalysis

Here we show that the activity of cobalt for the oxygen evolution reaction (OER) can be enhanced by confining it in the interlayer region of birnessite (layered manganese oxide). The cobalt intercalation was verified by employing state-of-the-art characterization techniques such as XRD, Raman and electron microscopy. It is demonstrated that the Co²⁺/birnessite electrocatalyst can reach 10 mA cm^-2 at an overpotential of 360 mV with near unity Faradaic efficiency. This overpotential is lower than that which can be achieved by using a pure cobalt hydroxide electrocatalyst for the OER. Furthermore, the Co²⁺/birnessite catalyst shows no degradation after 1000 electrochemical cycles.