Issue 5, 2016

Initial stages of water solvation of stepped platinum surfaces

Abstract

Platinum is an active catalyst for a large number of (electro)chemical reactions in aqueous solution. The observed catalytic activities result from an interplay between the intrinsic adsorption properties of platinum surfaces and their interaction with the aqueous environment. Although water networks have been extensively studied on close-packed surfaces, little is known about high-coverage solvation environments around defects. Here, we report DFT calculations on medium- to high-coverage water adsorption structures near the (100) step edge on Pt(533). We find that isolated ring structures adjacent to step edges form hexagons or pentagons. For higher coverages, 6 possible adsorption structures with varying ring sizes along the step edge and almost identical adsorption energies are observed. From our results we conclude that the favorable interaction of the H-down oriented water molecules, adjacent to the step edge, with the step dipole plays an important role in the formation of these structures. Furthermore, our results explain why water networks on stepped surfaces originate at the step edges, and extend towards the adjacent terraces, in agreement with previous experiments. These results show how step edges act as anchoring points for water adsorption and suggest that solvation of defects might dominate water structures on real platinum surfaces.

Graphical abstract: Initial stages of water solvation of stepped platinum surfaces

Supplementary files

Article information

Article type
Paper
Submitted
29 Jul 2015
Accepted
20 Aug 2015
First published
21 Aug 2015
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 3416-3422

Initial stages of water solvation of stepped platinum surfaces

M. J. Kolb, J. Wermink, F. Calle-Vallejo, L. B. F. Juurlink and M. T. M. Koper, Phys. Chem. Chem. Phys., 2016, 18, 3416 DOI: 10.1039/C5CP04468E

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