Adsorption of water and ethanol on noble and transition-metal substrates: a density functional investigation within van der Waals corrections

Abstract

We report the results of extensive computational investigation of the adsorption properties of water and ethanol on several Cu-, Pt-, and Au-based substrates, including the close-packed unreconstructed Cu(111), Pt(111), and Au(111) surfaces, defected metal substrates with on-surface low-coordinated sites generated by the intermixing of Pt-Cu and Pt-Au in the topmost surface layers and strained on-surface and sub-surface Pt-layers at Cu(111) and Au(111) substrates. The calculations are based on the density functional theory (DFT) within the van der Waals (vdW) correction. For all the substrates, we found that water and ethanol bind via the anionic O atom to the cationic one-fold coordinated on-top metal sites, which enhances the adsorbate-substrate Coulomb interactions. For water, both DFT and DFT + vdW calculations predict a flat geometry. For ethanol, the DFT and DFT + vdW results are in contrast, namely, DFT yields a perpendicular orientation of the C-C bond with respect to the surface, while we obtained a parallel orientation of the C-C bond using DFT + vdW, which maximizes the adsorption energies. Despite expected deviations due to the nature of the weak adsorbate-substrate interactions, we found that the adsorption energy of water and ethanol shows a linear dependence as a function of the position of the center of gravity of the occupied d-band, and hence, the magnitude of the adsorption energy increases as the d-band center position shifts towards the Fermi energy. Thus, it indicates hybridization between the O p- and metal d-states, which determines the magnitude of the adsorption energy of water and ethanol on clean, low-coordinated, and strained noble and transition-metal substrates.

Electrocatalytic Oxidation of Small Molecule Alcohols over Pt, Pd, and Au Catalysts: The Effect of Alcohol’s Hydrogen Bond Donation Ability and Molecular Structure Properties

“…Thus, the above rules are also explained from the viewpoint of adsorption energy. Table 2 lists the adsorption energies of water, methanol, and ethanol on Pt, Pd, and Au surfaces calculated by DFT all within the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof [34][35][36][37][38][39][40]. As shown in Table 2, the adsorption energies of water on Pt and Pd are similar, while the adsorption energies of methanol and ethanol on Pd are almost twice as high as those on Pt.…”

“…Chuancheng Jia et al proved that the highly active photo-generated intermediates on the surface of TiO 2 can freshen the inert Au surface oxides, thereby increasing the catalytic activity of the catalyst [43]. −0.56 [40] The apparent activation energies (E a ) for alcohol oxidation were measured and used to characterize the activity of the catalyst on electo-oxidizing alcohols [44]. Figures 12-14 show the linear sweep voltammetry (LSV) at different temperatures and their Arrhenius plots of alcohol eletro-oxidation on electrodes at peak potentials.…”

Ethanol, O, and CO adsorption on Pt nanoparticles: effects of nanoparticle size and graphene support

“…This configuration follows the results obtained in the literature for ethanol adsorption on Pt(111) slabs and extended Pt surfaces. [47][48][49] Carbon monoxide molecules were placed with the C-O bond being perpendicular to the nanoparticle facet.…”

“…Moreover, analysing the position of the molecule on top of the catalyst surface and how the electronic density of the molecule changes with the interaction can help to explain dissociation steps of ethanol. In the literature, it is possible to find a few theoretical studies performed for ethanol molecules on metallic monolayers, 47 slabs, 48,49 small nanoparticles, 50 and core-shell M@Pt nanoparticles. 51 For Pt surfaces, all the computational results showed adsorption energies lower than 1.0 eV, with a clear adsorption site preference for on top sites, and a crucial role of van der Waals interactions, which is responsible for changing the ethanol configuration adsorbed on metallic nanoparticles, favouring configurations with the C-C bond parallel to Pt surfaces.…”

Estudos de primeiros princípios da adsorção de água e de etanol sobre ligas de superfície de metais de transição sob efeitos de deformação expansiva e compressiva

“…Fonte: Adaptada de FREIRE; KIEJNA; DA SILVA. (256) possuem recobrimento parcial (ou seja, 56 % recobertas com átomos de Pt), as monocamadas (100 % recobertas com átomos de Pt) e as superfícies (111) para Cu, Pt e Au. Para facilitar o entendimento, adotaremos as nomenclaturas de substratos com "distorções" nas primeiras camadas, "monocamadas" e "compactas", respectivamente aos casos supracitados.…”