CO chemisorption at vacancies of supported graphene films: a candidate for a sensor?

Abstract

We investigate CO adsorption at single vacancies of graphene supported on Ni(111) and polycrystalline Cu. The borders of the vacancies are chemically inert but, on the reactive Ni(111) substrate, CO intercalation occurs. Adsorbed CO dissociates at 380 K, leading to carbide formation and mending of the vacancies, thus preventing their effectiveness in sensor applications.

Highly selective covalent organic functionalization of epitaxial graphene

“…1, we can derive the probability of creating a vacancy by an incident ion, because it shall equal the slope of the curve for low doses, and we can derive from our data that this value is about 0.02. Note that the required doses are very similar to that published24.…”

“…Interestingly, a recent work explores the catalytic activities promoted by the unsaturated dangling bonds that may remain on a surface after SAV formation24. However, those experiments were performed on epitaxial graphene on metals, and it has been shown by DFT calculations that the C atoms at the vacancy edge back-fold towards the metallic substrate promoting bonding with it (ref.…”

“…Our method is based on making use of the localized electrons appearing around atomic vacancies. The physics of induced point defects on graphene have emerged in the last years as a source of new controlled properties, giving rise to magnetism22, chemical properties23, catalysis24 or electronic doping25. Here we take advantage of the accumulation of charge at the dangling bond positions to promote new chemical reactions, as the selective binding of amino-terminated molecule.…”

Influence of growing conditions on the reactivity of Ni supported graphene towards CO

“…Single layer G films were grown in situ by surface catalysed dehydrogenation of ethene, according to well established recipes. 11,15 The substrate growth temperature (T g ) was varied between T g = 753 K and T g = 873 K, for the different growth protocols. Ethene was introduced into the UHV chamber through a doser placed ∼1 cm away from the Ni(111) surface.…”

“…8 In a recent investigation, we have demonstrated that weak CO chemisorption occurs at pristine G/Ni(111) sites 9,10 while a G layer grown on polycrystalline Cu is unreactive under identical conditions. 11 The value of the desorption energy of CO/G/Ni(111) as well as its reversible nature indicates the occurrence of non-dissociative chemisorption at pristine sites up to a coverage as high as 0.33 monolayers (MLs). This unexpected result indicates that the nature of the substrate and the strength of its interaction with G are critical in determining the a) Author to whom correspondence should be addressed.…”