Water Oxidation Catalyzed by Cobalt Oxide Supported on the Mattagamite Phase of CoTe₂

A chemical synthesis for the cobalt pertelluride mineral mattagamite is reported. Synthetic nanocrystalline mattagamite was investigated for electrochemical water oxidation and showed catalytic activity. Electrochemical water oxidation occurred at an overpotential of 380 mV at 10 mA/cm−2 with a Tafel slope of 58 mV/decade and with a Faradaic efficiency of 96% and turnover frequency of 0.021 s–1 at 0.5 V.