PtTiOx/OC electrocatalysts with improved durability in H2/O2 PEMFCs without external humidification

In the present investigation, PtTiOx/C-500-Ar electrocatalyst with excellent durability and the ability of water retention was prepared and characterized. Through transmission electron microscopy, PtTiOx/C-500-Ar electrocatalyst was observed to exhibit good particle size preservation during thermal treatment and durability testing. The combined results from single cell durability testing, scanning electron microscopy, electrochemical surface area of the electrocatalyst, and tests designed to inspect the variation of internal resistance, as well as performance of the fuel cell, demonstrated that fuel cell performance degradation was mainly caused by the increase of fuel cell internal resistance due to the hydrophilicity change of the membrane and the loss of electrochemical surface area in cathode electrocatalyst. The results also indicated that by using PtTiOx/C-500-Ar as both cathode and anode electrocatalysts, the single cell could be stably operated with dry gases without any external humidification. The PtTiOx/C-500-Ar electrocatalyst exhibited excellent durability during 518 h testing. These results imply that titanium oxide plays an important role in increasing the uptake of water and serving as an anchor for the adjacent platinum particles to prevent Pt particles from agglomeration and coalescence during the thermal treatment and durability testing. (c) 2007 The Electrochemical Society.