Promotion of oxygen reduction reaction durability of carbon-supported PtAu catalysts by surface segregation and TiO₂ addition

Highly effective carbon supported-Pt₇₅Au₂₅ catalysts for oxygen reduction reaction (ORR) are prepared though titanium dioxide modification and post heat treatment. After accelerated durability test (ADT) of 1700 cycles, the ORR activity of PtAu/C catalysts modified by TiO₂ and air heat treatment is 3 times higher than that of the commercial Pt/C. The enhancement of ORR activity is attributed to surface and structural alteration by air-induced Pt surface segregation and lower unfilled d states. On the contrary, for TiO₂ modified and H₂ treated PtAu/C catalysts, the deterioration of the ORR activity may be due to the loss of electrochemical surface area after ADT and the increase of d-band vacancy.