Nanoscale adhesion between Pt nanoparticles and carbon support and its influence on the durability of fuel cells

We report an atomic force microscopy (AFM) based method to characterize the adhesion between metal nanoparticles and carbon support that plays an important role in determining the durability of fuel cells. This adhesion is related to the electrochemical active surface area (ECSA). Force-distance curves measured with a Pt-coated AFM tip on the surface of the support allows us to probe the adhesion between a Pt nanoparticle and the support because an asperity between a Pt-coated AFM tip and carbon support can mimic the nanoscale interface between Pt nanoparticles and carbon. We found that acid-based surface treatment of the carbon support increases the adhesion force by a factor of 4, compared with the as-received carbon support. Meanwhile, surface treatment using acid on the carbon support can lead to a higher ECSA, which is consistent with the higher adhesion force probed with AFM. We attribute the higher adhesion between the Pt probe and the acid-treated carbon to stronger chemical interaction by the C/O functional groups.