Effects of transition metal doping in Pt/M-TiO2 (M = V, Cr, and Nb) on oxygen reduction reaction activity.

High cost and low durability are unresolved issues that impede the commercialization of proton exchange membrane fuel cells (PEMFCs). To overcome these limitations, Pt/TiO 2 is reported as an alternative electrocatalyst for enhancing the oxygen reduction reaction (ORR) activity and/or durability of the system. However, the low electrical conductivity of TiO 2 is a drawback that may be addressed by doping. To date, most reports related to Pt/doped-TiO 2 focus on changes in the catalyst activity caused by the Pt-TiO 2 interaction (metal-support interaction), instead of the effect of doping itself; doping is merely considered to enhance the electrical conductivity of TiO 2 . In this study, we discuss the variation in the electronic fine structure of Pt caused by the dopant, and its correlation with the ORR activity. More extensive contraction of the Pt lattice in Pt/M-TiO 2 (M = V, Cr, and Nb) relative to Pt/TiO 2 and Pt/C leads to outstanding ORR specific activity of Pt/M-TiO 2 . Notably, a fourfold increase of the specific activity is achieved with Pt/V-TiO 2 relative to Pt/C. Furthermore, an accelerated durability test (ADT) of Pt/V-TiO 2 demonstrates that this system is three times more durable than conventional Pt/C due to the metal-support interaction. [ABSTRACT FROM AUTHOR]