For decades there has been experimental indications of CO dissociation on different Pt surfaces. The dissociation appears to depend sensitively on the surface structures. When operating at high pressure, dissociation was reported at 500 K for Pt(100), whereas a temperature of 673 K was required for dissociation on Pt(111). The dissociation was reported to be associated with a roughening of the surface via the formation of platinum carbonyls. The subject is puzzling, in part due to the lack of theoretical results to support the experimental observations. However, most computational studies have been carried out on flat surfaces where the reaction is strongly endothermic. In this study, CO dissociation has been investigated by density functional theory (DFT) using the Vienna Ab Initio Simulation Package (VASP). The generalized gradient approximation functional PBE was used to describe exchange-correlation effects. The Kohn-Sham orbitals were expanded in plane waves and the core-valence interactions was described within the plane augmented wave (PAW) method. Different sites for CO dissociation were investigated by considering different surfaces and sites including platinum carbonyls. In accordance with previous studies, we find that direct dissociation from a low coverage state is highly activated and endothermic on flat surfaces such as Pt(111) and Pt(100) and also on stepped surfaces such as Pt(211). However, dissociation appears possible at special sites at high CO coverage. In this work we propose two model structures where CO dissociation is possible through a Boudouard pathway.

Sites for CO dissociation over platinum

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.