Electrochemical oxidation of methanol on mesoporous nickel phosphates and Si-incorporated mesoporous nickel phosphates

Mesoporous nickel phosphates (NiPOs) and Si-incorporated mesoporous nickel phosphates (Si-NiPOs) were used as catalysts for the electrochemical oxidation of methanol in alkaline medium. NiPO-2, with shorter nanotubes and higher Ni content, shows much higher activity than NiPO-3. Si incorporation drastically raises the electrochemical activity of the nickel phosphates. The Si-incorporated materials also exhibit good stability in the electrochemical environment. Electrochemical impedance spectroscopy studies show that the electron-transfer resistances (R-ct) are greatly reduced by Si incorporation (from 16 k Omega to 3 k Omega), indicating a faster electron-transfer process towards methanol oxidation. By optimizing the incorporated Si content in the framework of NiPO-2, the electrochemical activity is increased by a factor of 4. (C) 2012 Elsevier B.V. All rights reserved.