Glycerol Adsorption on Platinum Surfaces: A Density Functional Theory Investigation with van der Waals Corrections

Abstract

Glycerol has been suggested as an additional energy source for hydrogen production for fuel cell applications, and several experimental studies have been reported on glycerol conversion on transition-metal surfaces; however, our atomistic understanding of glycerol−metal interactions is still far from satisfactory. In this work, we will report a theoretical investigation of the adsorption properties of glycerol on the Pt(110), Pt(100), and Pt(111) surfaces based on density functional theory (DFT) calculations with van der Waals (vdW) corrections to the DFT total energy. In the lowest energy configurations, which differ by millielectron volts, glycerol is almost parallel to the Pt surfaces and interacts with the Pt surfaces via one of the hydroxyl groups near the on-top Pt sites, which strongly affects the orientation of glycerol relative to the surface. Our results and analyses indicate that the adsorbate structure is among the high energy configurations of glycerol in gas phase. The vdW correction enhances the adsorption energy and hence decreases the equilibrium glycerol−metal distance; in particular, it affects mainly the adsorbate structure for glycerol on Pt(110), leading to the binding of two edge glycerol hydroxyl groups to the Pt(110) surface. Moreover, the vdW correction enhances the magnitude of the glycerol adsorption energy more on Pt(111) and less on Pt(110) surfaces; however, without changing the relative order of the adsorption energies, that is, glycerol binds more strongly on Pt(110) and more weakly on Pt(111) surface. We found large work function changes (0.7−1.0 eV) upon glycerol adsorption and negligible changes in the Bader charges of the H, C, O, and Pt atoms, and hence, polarization effects play a crucial role in the interaction mechanism.

Glycerol adsorption on a defected Pt6/Pt(100) substrate: a density functional theory investigation within the D3 van der Waals correction

“…These results are supported by our previous ndings for alcohol molecules on close-packed TM surfaces. 22,27,28 As expected, the adsorbed structures in which glycerol binds on the terrace sites, e.g., structures F and G, are similar to the adsorbed structure with glycerol bound on the clean Pt(100) surface, that is, d O-Pt is 2.31 A and 2.33Å for structure F and the structure with glycerol bound on the clean Pt(100) surface, respectively.…”

“…17,22 In addition, the vdW correction increases the adsorption energy of the systems, however, the enhancement was found to be dependent on the surface structure.…”

“…Up to now, studies using theoretical ab initio calculations based on density functional theory (DFT) have reported only on the interaction of glycerol with perfect close-packed TM surfaces. [18][19][20][21][22] For example, it was found that the glycerol molecule adsorbs via its O atom on the on-top metal atom of close-packed TM surfaces, with the bond formed by its edge carbon atoms nearly parallel to the surface.…”

“…26 To improve the description of the long range non-local correlation effects, which play a crucial role in weak interacting systems such as water and ethanol adsorption on TM(111), 27,28 and glycerol adsorption on Pt surfaces, 22 we employed one of the van der Waals (vdW) corrections proposed by S. Grimme, namely, the D3 vdW correction. [29][30][31] The D3 vdW framework has been employed with great success in several studies.…”

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

“…(122) Os principais funcionais dentro dessa temática são vdW-DF,(119) também chamado vdW-DF1, vdW-DF2. (120) A implementação desses funcionais e correções da energia de dispersão, nos mais populares códigos de estrutura eletrônica, demonstrando grande aplicabilidade para um grande número de sistemas, (125,(132)(133)(134)(136)(137)(138)(139)(140)(141)(142) fez com que sua utilização e publicações relacionadas crescesse quase exponencialmente. No entanto, um entendimento claro do papel dessas interações em muitos sistemas permanecem, por vezes, não satisfatoriamente compreendidas, bem como há certas ressalvas quanto à confiabilidade das mesmas, necessitando ainda estudos mais detalhados ou comparativos.…”