A Density Functional Theory Study of Methoxy and Atomic Hydrogen Chemisorption on Au(100) Surface

Abstract

<div style="text-align:justify;"> <span style="line-height:19px;font-size:13px;" class="Apple-style-span"><span style="font-family:Verdana;font-size:12px;">The adsorption of CH</span>_{<span style="font-family:Verdana;font-size:12px;">3</span>}<span style="font-family:Verdana;font-size:12px;">O and H on the (100) facet of gold was studied using self-consistent periodic density functional theory (DFT-GGA) calculations. The best binding site, energy, and structural parameter, as well as the local density of states,</span><i> </i><span style="font-family:Verdana;font-size:12px;">of each species were determined. CH</span>_{<span style="font-family:Verdana;font-size:12px;">3</span>}<span style="font-family:Verdana;font-size:12px;">O is predicted to strongly adsorb on the bridge and hollow sites, with the bridge site as preferred one, with one of the hydrogen atoms pointing toward a fourfold vacancy (bridge-H hollow). The top site was found to be unstable, the CH</span>_{<span style="font-family:Verdana;font-size:12px;">3</span>}<span style="font-family:Verdana;font-size:12px;">O radical moving to the bridge –H top site during geometry optimization. Adsorption of H is unstable on the hollow site, the atom moving to the bridge site during geometry optimization. The 4-layer slab is predicted to be endothermic with respect to gaseous H</span>_{<span style="font-family:Verdana;font-size:12px;">2</span>}<span style="font-family:Verdana;font-size:12px;"> and a clean Au surface.</span></span> </div

DFT study of adsorption and diffusion of atomic hydrogen on metal surfaces

“…As regards the Au(100) surface, only H adsorption on the bridge and top sites was considered, since the hydrogen atom in hollow position, tended to move to the adjacent bridge site during geometry optimization. This behavior had been previously observed by N'Dollo et al [40]. Thus, the lowest recorded energy was the one for the bridge site, with a value of −3.27 eV , resulting in the most stable site for adsorption.…”

“…The adsorption energies and diffusion pathway were calculated for hydrogen atoms on (100) surfaces of representative metals: Au, Cu, Ag and P t. First, the adsorption energies of the hydrogen atom on the three different adsorption sites (hollow, bridge and top) were calculated and the obtained values were compared with previous reports [3,17,18,35,36,37,38,39,40]. In some of that works, Moussounda et al [35] and Nave et al [17] have studied the adsorption energy for a single H atom and then for a single CH 3 on P t(100) in order to find the dissociation pathway of CH 4 on this surface.…”

Density functional theory study of O–H and C–H bond scission of methanol catalyzed by a chemisorbed oxygen layer on Cu(111)

“…system with adsorbate and ref E is the energy of the structure that we used as a reference to compare the relative stability, and more specifically, it is the total energy of the system without an adsorbate on the surface. gas E is the energy of a molecule in its gas phase, calculated by placing an isolated molecule in a box, and N ads is the number of molecules newly adsorbed into the system, which is Although the adsorption energies calculated using the above equation 6 should be given with respect to stable gas-phase species (in our case, CH 3 OH was used, as well as O 2 as reference for atomic O adsorption and H 2 as reference for atomic H adsorption), we found that the convention was to continue to use the above equation for the adsorption energies of the reaction intermediates, regardless of them being radicals[15,[58][59][60] and we thus followed the convention in order to make comparable results. The atomic structures and charge difference are visualized using the VESTA package[61,62].…”

Density functional theory (DFT) investigation of the adsorption of the CH3OH/Au(100) system

“…Details of the calculations of the structures and energetics of adsorbed CH 3 O and H can be found in our previous publication . Methoxy was investigated at each of the symmetric sites.…”

“…The top site was found to be unstable, the radical methoxy moving to the bridge site during geometry optimization. The bridge (Ox) (or bridge H‐hollow in Ref …”