Nature of Lone-Pair–Surface Bonds and Their Scaling Relations

Abstract

We investigate the (surface) bonding of a class of industrially and biologically important molecules in which the chemically active orbital is a 2 p electron lone pair located on an N or O atom bound via single bonds to H or alkyl groups. This class includes water, ammonia, alcohols, ethers, and amines. Using extensive density functional theory (DFT) calculations, we discover scaling relations (correlations) among molecular binding energies of different members of this class: the bonding energetics of a single member can be used as a descriptor for other members. We investigate the bonding mechanism for a representative (HO) and find the most important physical surface properties that dictate the strength and nature of the bonding through a combination of covalent and noncovalent electrostatic effects. We describe the importance of surface intrinsic electrostatic, geometric, and mechanical properties in determining the extent of the lone-pair-surface interactions. We study systems including ionic materials in which the surface positive and negative centers create strong local surface electric fields, which polarize the dangling lone pair and lead to a strong "electrostatically driven bond". We emphasize the importance of noncovalent electrostatic effects and discuss why a fully covalent picture, common in the current first-principles literature on surface bonding of these molecules, is not adequate to correctly describe the bonding mechanism and energy trends. By pointing out a completely different mechanism (charge transfer) as the major factor for binding N- and O-containing unsaturated (radical) adsorbates, we explain why their binding energies can be tuned independently from those of the aforementioned species, having potential implications in scaling-driven catalyst discovery.

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

“…Thus, as a large amount of the ethanol adsorption energy arises from dispersion interactions, which are not largely affected by the Pt nanoparticle size, and as we see a small interaction between ethanol and d states from the Pt surface, it is understandable that nanoparticle size effects are less important for ethanol adsorption. Additionally, a recent work from Kakekhani et al 90 demonstrated that the covalent contributions can be much less important for the adsorption energies of closedshell adsorbates such as water, alcohols, ammonia, on metallic surfaces than for unsaturated intermediates such as O, OH, CO. The authors show that the correlation slope between adsorption energies of water and O is small, helping to explain the small slope in the correlation between ethanol adsorption energies and descriptors such as the generalized coordination number or d-band centres, which can successfully describe the O adsorption.…”

“…40 The bond lengths contractions and d-band centre downshifts are associated with weaker adsorption energies and can be used to explain the support effect for O and CO. For ethanol, our previous results demonstrated that the Pt-Pt bond lengths and d-band centre changes induced by size effects are not able to change the ethanol adsorption energies to this extent. Recently, Seminovski et al 91,92 and Kakekhani et al 90 demonstrated that the ethanol adsorption is stronger on cationic adsorption sites and that in some cases the electrostatic effects can be dominant. 90 Thus, a possible explanation for the support effect for ethanol adsorption can be the change in the atomic charges for the surface Pt atoms.…”

Solvent–Adsorbate Interactions and Adsorbate-Specific Solvent Structure in Carbon Dioxide Reduction on a Stepped Cu Surface

“…32,[42][43][44] Recent theoretical work has provided a systematic understanding of of how various surface properties affect surface binding of water. 45 Several studies have also investigated the effects of explicitly including pH. 40,46,47 Although the reaction thermochemistry is often investigated without the explicit consideration of the electrolyte, 48 it has been demonstrated that ions can significantly affect the thermodynamics due to field effects.…”

Electrostatic Origins of Linear Scaling Relationships at Bifunctional Metal/Oxide Interfaces: A Case Study of Au Nanoparticles on Doped MgO Substrates

“…Apart from atomic adsorbates and their hydrogenated homologues at the interface,b ifunctionally bound species,a dsorbing on both Au and MgO components,a lso exhibit linear scaling.F or example, COOH* ( (Table 1; Supporting Information, Figure S10), CH 3 OH*( Supporting Information, Figure S11), and CH 3 CH 2 OH* (Supporting Information, Figure S12), which have been shown to exhibit scaling properties owing to lone-pair interactions on metals, [29] also display scaling trends at the Au/MgO interface.F urther examples of SRs involving WGS and methanol synthesis intermediates are provided in Table S4 of the Supporting Information. Overall, the SRs show minimal scatter,w ith aMAE of 0.05 eV across SRs for 31 adsorbates.…”