The surface chemistry of cuprous oxide

• Small molecule interactions with monolayers, thin films, and bulk Cu 2 O are reviewed. • Monolayer Cu 2 O films are better models for oxidized metallic copper rather than Cu 2 O. • Cu 2 O single crystals are ideal for fundamental reactivity studies. • The prospect of using Cu 2 O as a support for single atom catalysts is presented. The chemical and electronic properties of copper combined with its large natural abundance lend this material to impact a wide range of technological applications, including heterogeneous catalysis. The reactivity of copper in its Cu 1+ oxidation state makes this specific configuration relevant in various chemical reactions, but the facile redox properties of copper make the isolation of individual states for fundamental studies difficult. Here we review three Cu 2 O model systems used to study the interaction of Cu 1+ with small molecules making use of surface science techniques: Cu 2 O/Cu(111), thin polycrystalline Cu 2 O films on Cu foil, and bulk Cu 2 O crystals. Advantages and disadvantages of each system are discussed and exemplified through case studies of chemical adsorption and reactivity studies.