Enhanced Activity and Stability of TiO2-Coated Cobalt/Carbon Catalysts for Electrochemical Water Oxidation

TiO2-coated Co/C catalysts prepared by atomic layer deposition (ALD) were used to study the effect of TiO2 overcoating on a Co/C catalyst for electrochemical water oxidation. The Co/C catalyst with a thin-layer overcoating of TiO2 (ALD(TiO2)-Co/C) demonstrated 2.5 times higher turnover frequency (TOF) than the Co/C catalyst for the reaction. The TOF of the ALD(TiO2)-Co/C catalyst increased when the ALD(TiO2) coating cycle number was increased from 5 to 60. In addition, the stability of the 60 cycle ALD(TiO2)-Co/C catalyst was enhanced compared to the Co/C catalyst. This work shows how the ALD synthesis technique can be used to improve the catalytic activity and stability of nonprecious-metal-based catalysts like Co/C for electrochemical water oxidation.