A comparative study of the interaction of platinum with group 4A (germanium, tin and lead) porphyrins.

Because of its vast number of applications and high price many studies have been made on how to reduce the amount of platinum in catalysts. One method includes dispersing platinum nanoparticles in porous support materials. But electrically conductive carbon-based support materials-needed for fuel cell electrodes-permit nanoparticles to migrate and form larger clusters, leading to reduced catalytic activity over time. To find a solution to this problem, we modelled the interaction of group 4A metal porphyrins (germanium (II) porphyrin (GePor), tin (II) porphyrin (SnPor) and lead (II) porphyrin (PbPor)) with platinum (Pt) using density functional theory. We showed that platinum can bond strongly on both germanium porphyrin and tin porphyrin. More importantly, valence Pt d-orbital characteristics dominate their HOMO and HOMO-1. Our study indicates that dispersing Pt as individual atoms on a SnPor and GePor surface is a good way to minimize platinum load in carbon-based reduction catalysts for reactions involving mainly the HOMO and HOMO-1 of Pt, of which the oxygen reduction reaction in fuel cells is an example.