Degradation of Pt/C electrocatalysts having different morphology in low-temperature PEM fuel cells

Resumo

The electrochemical degradation of platinum–carbon catalysts with different morphology has been studied under model conditions in low-temperature proton exchange membrane fuel cells. It has been found that catalysts with an average size of platinum nanoparticles ranging from 2 to 3 nm uniformly distributed over the carbon support exhibit the best current–voltage characteristics; however, they have also the highest degradation rate. It is shown that the main cause of Pt/C electrocatalyst degradation consists of both the detachment of small platinum particles from the carbon support and the recrystallization of platinum, leading to an increase in the average particle size. On the contrary, the catalysts having the initial average size of platinum particles ranging from 3 to 4 nm show a considerable stability in current–voltage characteristics even after 10000 cycles of accelerated degradation.