Mesoporous TiO2 as the Anode Catalyst Support for Solid Polymer Electrolyte Water Electrolysis

TiO2 support was prepared through evaporation-induced self-assembly ( EISA) by using butyl titanate as starting material. Three TiO2 samples were calcined at different temperatures and then IrO2 was loaded on them with a mass ratio of IrO2/TiO2 of 2/3 by a modified Adams fusion method. The samples were characterized by X-ray diffraction ( XRD), specific surface area measurement, thermogravimetric and differential scanning calorimetry analysis ( TGA-DSC), transmission electron microscopy ( TEM) and electrochemical testing. The electrochemical activity of the catalysts was investigated in a single cell proton exchange membrane(PEM) electrolyzer consisting of a PVC cathode and a Nafion117 membrane. The results suggested that as the calcination temperature increased, the mesoporous structure of TiO2 was destroyed, the pore size increased and the pore volume reduced, and the phase of TiO2 transferred from anatase to rutile structure. Utilization of the TiO2 support resulted in a reduction in the size of the IrO2 crystallites and improved the distribution of catalyst. It was found that the lower the specific surface area of the support was, the higher the electrochemical activity of the catalyst was. This is most likely due to the formation of a conductive IrO2 film on the surface of non-conductive supports with 40% ( mass fraction) loading of IrO2. The IrO2, 40% IrO2/TiO2-2 and 40% IrO2/TiO2-3 catalysts showed a polarization potential of 2. 024, 2. 426 and 2. 064 V, respectively, under a current density of 1. 0 A/cm(2). These results suggest that the surface structure of the support has a great influence on the catalytic activity of IrO2.