Oxygen-deficient titania as alternative support for Pt catalysts for the oxygen reduction reaction

Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction (ORR) due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x, and TiO2-xNy were obtained by thermal treatment of anatase TiO2 under flowing H-2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N-2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HClO4. Pt/TiO2-x and Pt/TiO2-xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x, and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiO2-x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.