Title:	Chemistry on the Cuprite surface
DNr:	SNIC 2016/1-155
Project Type:	SNIC Medium Compute
Principal Investigator:	Tore Brinck <tore@kth.se>
Affiliation:	Kungliga Tekniska högskolan
Duration:	2016-04-01 – 2017-02-01
Classification:	10407 10403 10402
Homepage:	https://www.kth.se/profile/tore/
Keywords:

Abstract

We are applying for continued allocation on the Triolith supercomputer cluster in order to extend and finish our ongoing computational study of the physical and chemical surface properties of Cu2O. The aim of the study is to provide insight into fundamentally and industrially important processes taking place on the oxide surface. These include water splitting, corrosion, sulfidation and catalytic behavior in methanol synthesis and in the low-temperature water-gas shift reaction. Furthermore, since copper (one of our most common base materials) is covered by an oxide film in most real applications, understanding of the behavior of Cu2O is of broad general interests. One particular application of interest is the long-term storage of spent nuclear fuel in copper canisters. The studies will be carried out in close collaboration with experimental physicists’ at KTH Kista. Density functional theory (DFT) computations will be used in conjuction with experimental data obtained by electron microscopy techniques (STM), electron diffraction (LEED) and photo electron spectroscopy (XPS, UPS) at KTH and Maxlab facilities. In previous parts of this project we have been able to characterize the structure of the Cu2O(100)-surface (Soldemo et al., J. Phys. Chem. C, 2016, 120, 4373–4381). Using DFT combined with experimental studies, funded in part by Vetenskapsrådet (VR), we have also been able to shed light on the nature of the Cu2O(100)-H2O interface by resolving the composition of the first adsorption layer under different conditions. Our studies have in addition provided insight into the arrangement of the oxide surface underneath the wetting layers, which is an important general breakthrough. Two manuscripts on this topic are currently in the process of being finalized. On a computational level we have worked out a useful methodology for investigations of the cuprite-water system. This is based on a vast benchmark study including DFT-functionals of different classes. In the continued project we will extend our investigations to other crystallographic facets of Cu2O and apply our methods on problems closely related to the previously studied. These include studies of the interactions of carbon monoxide and methanol on the oxide surface. An explicit goal in the future is to study the sulfidation process of Cu2O. In the postulated scenario for the long-term storage of spent nuclear fuel, sulfides are envisioned as the leading corrodent of the encapsulating copper canister. Therefore it is important to understand the mechanism for exchanging the initial protecting Cu2O-film to Cu2S. The process of sulfidation is also important for Cu2O-catalsysis since H2S is known to be a potent suppressor of catalytic activity. We apply for a medium size project since we believe that the scope of our project motivates such an allocation. In order to study appropriately sized models, allocations larger than those provided for the small projects are needed.