Charging of dielectric surfaces in contact with aqueous electrolyte -- the influence of CO
arXiv:2201.11029 · doi:10.1021/jacs.2c06793
Abstract
The charge state of dielectric surfaces in aqueous environments is of fundamental and technological importance. Here, we study the influence of dissolved molecular CO on the charging of three, chemically different surfaces (SiO, Polystyrene, Perfluorooctadecyltrichlorosilane). We determine their charge state from electrokinetic experiments. We compare an ideal, CO-free reference system to a system equilibrated against ambient CO conditions. In the reference system, the salt-dependence is weakened for SiO and inverted for the organic surfaces. We show that screening and pH-driven charge regulation alone cannot explain the observed effects. As additional cause, we tentatively suggest dielectric regulation of surface charges due to a diffusively adsorbed thin layer of molecular CO. The formation of such a dynamic layer even at the hydrophilic and partially ionized silica surfaces is supported by a minimal theoretical model and results from molecular simulations.
Extended and thoroughly revised version with newly generated data from MD simulation, improved interpretation, Main text and supplementary materials, 29 Pages, 17 figures, published in JACS