International Journal of Hydrogen Energy, Vol.37, No.17, 12081-12088, 2012
Non-conductive TiO2 as the anode catalyst support for PEM water electrolysis
The applicability of a non-conductive TiO2 as the support of the anodic catalyst for PEM water electrolysis was tested. Three TiO2 samples with different specific surface areas were modified by IrO2 using a modified version of the Adams fusion method. A constant weight ratio of IrO2/TiO2 of 0.6 was maintained in all cases. The size, specific surface area and morphology of IrO2 electrocatalyst crystallites were investigated by X-ray diffraction, nitrogen adsorption (BET) and scanning electron microscopy, respectively. The electron conductivity of compressed catalyst powders was evaluated. Their electrochemical properties were studied on a rotating disk electrode (RIDE) and finally in a laboratory electrolyser. Utilization of the TiO2 support resulted in a reduction in the size of the IrO2 crystallites. It was found that the lower the specific surface area of the supports, the higher was the electrochemical activity of the catalyst. This is most likely due to the formation of a conductive IrO2 film on the surface of non-conductive supports. For the supports with a higher surface area, the amount of IrO2 used was not sufficient to form an adequately compact film. This resulted in high electron resistance of such a catalyst. The RIDE results were confirmed by a laboratory electrolysis test. Taken together with the excellent stability of TiO2 in an anodic environment, these results suggest that these materials are promising supports if the appropriate amount of iridium is deposited. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Keywords:Water electrolysis;Electrocatalyst support;Conductivity;Electrocatalyst utilization;Electrocatalytic activity