Improved stability of mesoporous carbon fuel cell catalyst support through incorporation of TiO2

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 N2 purged 0.5 M sulfuric acid. XRD analysis revealed that TiO2 was present in the anatase phase. The mean Pt particle diameter was ∼6 and ∼4 nm 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 0.05 to 1.25 V vs. RHE. This was evident from the observation that the support with TiO2 retained ∼53% of the electrochemically active surface area relative to the state observed after 100 cycles, whereas ∼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 gPt−1). After 1000 cycles the mass activity decreased to 10 A gPt−1 for the case without TiO2, whereas with TiO2 the deactivation was minor; i.e., the mass activity after 1000 cycles was 17 A gPt−1.