The electrochemical stability of Pt deposited on mesoporous carbon which was either applied in its unmodified state or coated with 20 wt%TiO2 was investigated by cyclic voltammetry in N-2 purged 05 M sulfuric acid XRD analysis revealed that TiO2 was present in the anatase phase The mean Pt particle diameter was similar to 6 and similar to 4 rim for mesoporous carbon with and without TiO2 respectively Pt supported on TiO2 modified substrates was more stable than Pt supported on conventional mesoporous carbon when subjected to 1000 cycles in the potential range from 005 to 1 25 V vs RHE This was evident nom the observation that the support with TiO2 retained similar to 53% of the electrochemically active surface area relative to the state observed after 100 cycles whereas similar to 33% of the active area remained in the case without TiO2 The oxygen reduction mass activity was identical for both fresh samples (i e 18 A g(Pt)(-1)) After 1000 cycles the mass activity decreased to 10 A g(Pt)(-1) for the case without TiO2 whereas with TiO2 the deactivation was minor I e the mass activity after 1000 cycles was 17 A g(Pt)(-1) (C) 2010 Elsevier Ltd All rights reserved