Effect of Air-Aging on the Electrochemical Characteristics of TiO x C y Films for Electrocatalysis Applications

We report on the electrochemical characteristics of pristine and air aged carbon modified titania electrodes in acidic electrolyte, which find application as catalyst supports in electrocatalysis. Films of different chemical composition (including TiO2, TiOx, TiO, TiC, C) are synthesized through a carbothermal treatment of compact anodic TiO2 on Ti substrates at different temperatures, and analyzed with X-ray photoelectron spectroscopy. Their activity towards heterogeneous outer sphere electron transfer and their stability against passivation and corrosion under anodic polarization are investigated by means of electrochemical impedance spectroscopy. It is found that a high fraction of TiC in the pristine carburized films in combination with a thin TiO2 surface layer yields high electron transfer kinetics even after aging for ~9 months, and a high corrosion and passivation resistance until ~0.74VSHE. This finding is essential to the material's application as catalyst support in general.