Impact of co-adsorbed oxygen on crotonaldehyde adsorption over gold nanoclusters: a computational study

Abstract

Crotonaldehyde (2-butenal) adsorption over gold sub-nanometer particles, and the influence of co-adsorbed oxygen, has been systematically investigated by computational methods. Using density functional theory, the adsorption energetics of crotonaldehyde on bare and oxidised gold clusters (Au13, d = 0.8 nm) were determined as a function of oxygen coverage and coordination geometry. At low oxygen coverage, sites are available for which crotonaldehyde adsorption is enhanced relative to bare Au clusters by 10 kJ mol(-1). At higher oxygen coverage, crotonaldehyde is forced to adsorb in close proximity to oxygen weakening adsorption by up to 60 kJ mol(-1) relative to bare Au. Bonding geometries, density of states plots and Bader analysis, are used to elucidate crotonaldehyde bonding to gold nanoparticles in terms of partial electron transfer from Au to crotonaldehyde, and note that donation to gold from crotonaldehyde also becomes significant following metal oxidation. At high oxygen coverage we find that all molecular adsorption sites have a neighbouring, destabilising, oxygen adatom so that despite enhanced donation, crotonaldehyde adsorption is always weakened by steric interactions. For a larger cluster (Au38, d = 1.1 nm) crotonaldehyde adsorption is destabilized in this way even at a low oxygen coverage. These findings provide a quantitative framework to underpin the experimentally observed influence of oxygen on the selective oxidation of crotyl alcohol to crotonaldehyde over gold and gold-palladium alloys.

Chemical Looping Technology in Mild‐Condition Ammonia Production: A Comprehensive Review and Analysis

“…[40,72] The DFT results further corroborate the above conclusions that the doping of transition metals (e.g., Fe, Co and Ni) is able to modulate the local electronic structure of manganese nitride, which subsequently lowers the formation energy of nitrogen vacancies and the energy barrier of nitrogen diffusion. [73] In addition, Ni dopants in the surface can effectively adsorb and activate H 2 molecules, thereby accelerating the hydrogenation and removal of N atoms [74] n…”

“…[ 59 ] Electronic structure calculations demonstrate that H 2 is mostly adsorbed in molecular form on the material surface, which is attributed to the insufficient ability of pure manganese nitride to the activation and dissociation of H 2 molecules. [ 40,71 ] Fe is only capable of reducing the Mn─N bond strength and the energy barrier of lattice N diffusion by increasing the occupancy of the d‐band center. [ 24b,42a ] However, it fails to improve the kinetics of lattice N reaction with H atoms, while Li can simultaneously lower the formation energy of nitrogen vacancies and facilitate the dissociation of H 2 molecules.…”

Structural and electronic changes in the Ni13@Ag42 nanoparticle under surface oxidation: the role of silver coating

“…It is wellknown that the magnetic properties of transition metals 17,18 are influenced by their corrosion. The impact of different environments, such as CO [19][20][21][22][23] and O 2 , 24 on nickel and another transition metal clusters has been extensively studied, revealing a decrease in the magnetic moment.…”

“…The structural evolution of metallic clusters when exposed to various environments significantly affects their properties. [21][22][23][25][26][27][28][29] For gold nanoclusters, 22 calculations underscore the significance of both surface coverage and the location of adsorbed oxygen in influencing the stability of co-adsorbed crotonaldehyde, the desired product in crotyl alcohol selox, while for paladium nanoclusters, 23 elevated CO coverages favored the formation of bridge-bound CO bonds, with some hollow-bound CO. The study predicted a coverage-dependent spectroscopic blue-shift in vibrational IR bands of adsorbed CO, coinciding with a 3.5% expansion of the palladium nanoparticle.…”