CO on Supported Cu Nanoclusters: Coverage and Finite Size Contributions to the Formation of Carbide via the Boudouard Process

Abstract

The interaction of carbon monoxide with an ordered array of copper nanoclusters was investigated under ultrahigh vacuum conditions by means of in situ X-ray photoelectron spectroscopy in combination with density functional theory calculations. The Cu clusters were supported on an alumina template grown on the Ni 3 Al(111) termination. Adsorption and dissociation of carbon monoxide occur at the copper clusters, yielding accumulation of carbidic carbon at the metal particles through the Boudouard process. The involved mechanisms are investigated at the atomic level, unveiling the effects of cluster finite size, reconstruction, support, and of local CO coverage. It is found that the high coverage of CO at the cluster surface, which considerably exceeds that achievable on single crystal surfaces, facilitates the metal restructuring and the reaction, yielding carbon incorporation into the bulk of the particles.

Reaction Network of Methanol Synthesis over Cu/ZnO Nanocatalysts

“…[4][5][6]. Moreover, using deposited cluster models consisting on the order of ten metal atoms is commonplace in state-of-the-art computational catalysis studies [120][121][122][123][124][125] in which chemical interactions and reactions are studied based on non-semiempirical electronic structure methods (it is noted that these studies are mostly carried out in the static optimization limit, whereas we carry out full ab initio simulations at finite temperature in the present investigation). Most importantly, studying heterogeneous catalysis in the limit of small, size-selected clusters is by now a well-established and useful contribution to understanding the related industrial processes [126][127][128][129][130][131][132] .…”

High‐Quality Graphene Using Boudouard Reaction

“…Moreover, it implies that a rate‐limiting step (if any) for the graphene synthesis happens on the grain border. According to the literature, the growth rate can be limited by several processes, [ 46 ] including CO chemisorption ( E ad = 0.3–0.8 eV normally [ 47 , 48 ] and up to 1.8 eV in exotic cases [ 49 ] ), diffusion [ 50 ] ( E d = 1 eV), catalytic decomposition of CO molecule ( E dec = 2–4 eV), [ 51 , 52 ] and attachment [ 53 ] of the carbon atom to the growing front of the nucleus ( E att = 2 eV). The last process is more likely to contribute the most to the limiting process.…”

Substrate- to Laterally-Driven Self-Assembly Steered by Cu Nanoclusters: The Case of FePcs on an Ultrathin Alumina Film

“…Adsorption of CO on the bare alumina thin film and consequent formation of carbonate species is not expected even at the mbar regime . On the other hand, small Cu clusters promote CO adsorption and decomposition even under ultrahigh-vacuum conditions and liquid nitrogen temperature, yielding accumulation of atomic carbon via the Boudouard process . For this reason, preliminary check measurements were performed on the pristine and on the Cu-decorated alumina surfaces.…”

“…29 On the other hand, small Cu clusters promote CO adsorption and decomposition even under ultrahigh-vacuum conditions and liquid nitrogen temperature, yielding accumulation of atomic carbon via the Boudouard process. 30 For this reason, preliminary check measurements were performed on the pristine and on the Cu-decorated alumina surfaces. We did not detect vibrational signal from the C−O stretch modes (see Figure S3), unless FePc molecules were deposited.…”