Diffusion mechanism of platinum nanoclusters on well-aligned carbon nanotubes

Abstract

Carbon supported platinum (Pt/C) remains among the preferred catalyst materials for use in proton exchange membrane fuel cells; however, its durability must be improved. In this work, we considered well-aligned carbon nanotubes (WACNTs) as a carbon support material and investigated the diffusion mechanism of Pt nanoparticles by using molecular dynamic (MD) simulations, including calculation of the binding energy, aggregation probability, and the diffusion coefficient. Moreover, the use of graphene as a support material is also examined. The trenches in well-aligned carbon nanotubes were found to not only increase the binding energy between the Pt particles and the substrates but also decrease the aggregation probability of Pt particles compared with the graphene substrates. Furthermore, we estimated the Pt mass per substrate area (Pt loading) when there is no occurrence or a reduced occurrence of Pt agglomeration: a value of 0.167 μg cm⁻² for WACNTs (24, 24), and a Pt particle diameter of 2.4 nm are suggested.