Preparation and characterization of titanium suboxides as conductive supports of IrO2 electrocatalysts for application in SPE electrolysers

A novel chemical route for the preparation of titanium suboxides (TinO2n−1) with Magneli phase was developed. The ceramic powders were prepared from TiCl4 by complexation of Ti ions and successive decomposition of the complex to form an amorphous oxide. A high temperature reduction (1050 °C) of the amorphous oxide was carried out by using diluted hydrogen. IrO2 electrocatalysts supported on Ti-suboxides were prepared by incipient wetness. The chemistry, morphology and structure of the materials were studied by TPR, XRF, XPS, BET, TEM and XRD. The electrochemical activity for oxygen evolution in a solid polymer electrolyte (SPE) electrolyser of IrO2 catalysts supported on a commercial titanium suboxide (Ebonex®) and TinO2n−1 prepared in-house was investigated by ac-impedance spectroscopy, linear sweep and cyclic voltammetry. The results showed proper electronic conductivity for both electrocatalysts and superior electrocatalytic activity of the catalyst based on the Ti-suboxides prepared in-house compared to the commercial support. In situ cyclic voltammetry and ac-impedance analyses showed larger voltammetric charge and double layer capacitance for the catalyst based on the Ti-suboxides prepared in-house with respect to the catalyst supported on Ebonex®. These results were attributed to the better dispersion and larger occurrence of active catalytic sites on the surface of the suboxide prepared in-house based anode compared to the anode based on the commercial support.