To investigate the O 2 molecular and dissociative adsorption mechanisms, we have computed the O 2 dissociation barriers The energy profiles for the different Pt 4 Ge n clusters are collected in Figure . Here, we only show the results for the pathways with the most stable Pt 4 Ge n 2O final state (FS) adducts for each cluster; the rest of the isomers are depicted in Figures S4-S7 of the SI.