CO Dimerization on Cu Nanoparticles under High CO Coverage

Abstract

Copper has attracted significant interest as a catalyst for thermal and electrochemical CO2 or CO reduction into valuable compounds. These reactions may involve significant quantities of CO adsorbed on the surface of Cu catalysts, whose properties are typically affected by nanostructuring. Here, we applied density functional theory (DFT) calculations to study the effect of CO coverage on the catalytic properties of 0.8 nm large Cu38 and 1.1 nm large Cu79 nanocrystallites. Even under mild conditions, CO is calculated to saturate the surface of Cu nanoparticles at an unusually high coverage of 1 ML. At this coverage, CO is calculated to adsorb predominantly on top sites, with some CO molecules occupying bridge sites on the {111} facets. Such high quantities of adsorbed CO led to profound changes in the electronic structure of surface Cu atoms, whose d-band center positions shift to lower energies by more than 0.7 eV. CO coverage was also calculated to have a profound effect on the catalytic properties of Cu particles in the exemplary reaction of CO dimerization into OCCO. Unexpectedly, the barriers for OCCO formation were calculated to increase by ∼0.6 eV at high CO coverage on Cu nanoparticles due to the intricate effect of coadsorbates on OCCO binding to Cu. Thus, the interplay between nanostructuring and adsorbate coverage is shown to have significant implications for heterogeneous catalysis and electrochemistry that are hard to predict based on chemical intuition.

Selectivities of Stepped Cu–M (M = Pt, Ni, Pd, Zn, Ag, Au) Bimetallic Surface Environment for C1 and C2 Pathways

“…In this study, we delved into the creation of a novel series of Cu-based bimetallic catalysts (BMCs). The Cu (111) surface stands out with its exceptional selectivity for CO dimerization, while simultaneously boasting the lowest surface energy, making it a superior surface for relevant applications . The model was achieved by introducing a carefully designed metal M (M = Pt, Ni, Pd, Zn, Ag, Au) onto the stepped surface of the Cu (111) surface.…”