Structural change of the Pt/C electrocatalyst in humidified air observed by in situ TEM

The polymer electrolyte fuel cell (PEFC) is a promising energy source for automobile application. One of the auto industry's challenges is to start the commercialization of fuel cell vehicles (FCVs) at a reasonable price in 2015. From the viewpoint of their performance, however, the durability of electrode materials of PEFC still remains a major technical issue. For example, electrocatalysts need to achieve potential-cycle durability corresponding to a target of actual FCV operation.1 A typical analysis method to investigate the degradation of electrocatalysts is to observe the catalyst sample taken out of an membrane electrode assembly (MEA). Although this method has an advantage that the electrocatalyst has been exposed to the reactant gas and the potential cycles simulating the operation of a fuel cell, it has a fata