Lateral water structure connects metal oxide nanoparticle faces

Abstract

When a metal oxide surface is immersed in aqueous solution, it has the ability to bind, orient, and order interfacial water, affecting both chemical and physical interactions with the surface. Structured interfacial water thus possesses time-averaged, spatially varying polarization charge and potential that are comparable to those arising due to ion accumulation. It is well established that interfacial water structure propagates from the surface into bulk solution. Here, we show that interfacial water structure also propagates laterally, with important consequences. The constant pH molecular dynamics was used to impose a pH difference between opposite faces of a model goethite (a-FeOOH) nanoparticle and quantify water polarization charge on intervening faces. We find that the structure of water on one face is strongly affected by the structure on nearby surfaces, revealing the importance of long-range lateral hydrogen bonding networks with implications for particle aggregation, oriented attachment, and processes such as dissolution and growth.

Interplay between Facets and Defects during the Dissociative and Molecular Adsorption of Water on Metal Oxide Surfaces

“…In the present study, we compare the hydroxylation behavior of (001), (012), and (104) surfaces, each separately expressed as the dominant facet on facet-engineered hematite nanoparticles. , This morphological control enabled us to largely disregard synergistic/antagonistic effects between facets ,, that might exist in a multi-faceted crystallite, enabling focus on one crystal facet at a time. − We use synchrotron-based AP-XPS to investigate the influence of surface orientation on the propensity to form point defects and its resultant effect on the hydroxylation and hydration of hematite. We show experimentally for the first time that oxygen vacancies, readily generated under mild surface preparation conditions, play a commanding role compared to the pristine, defect-free counterpart.…”

Ion complexation waves emerge at the curved interfaces of layered minerals

“…Layered minerals control carbon, water, nutrient, and critical element transport in the lithosphere 1 – 6 , lubricate fault slip 7 – 9 , and promote cloud formation 10 through interactions among charged, hydrated interfaces 11 . Consequently, intermolecular forces that control ion and water distributions at the mineral-aqueous interface have been widely investigated 12 – 16 via measurements of the potential drop at the interface 17 , the change in orientation and density of water molecules 18 – 20 , and ordering of water and counterions 21 – 25 . Electric double layer (EDL) models that form the basis of Derjaguin Landau Verwey Overbeek (DLVO) theory accurately describe mica surfaces in monovalent (e.g., Li + , Na + , K + ) electrolyte 26 but provide an incomplete description 27 of clay mineral behavior such as swelling pressure 28 .…”

Cubes to Cubes: Organization of MgO Particles into One-Dimensional and Two-Dimensional Nanostructures

“…The transformation behavior of metal oxide particles in aqueous environments is characterized by a variety of interaction pathways that include oriented attachment and dissolution–recrystallization processes. − In that regard, particles with characteristic and defined crystal habits are promising building units to generate spatially organized nanostructures composed of uniformly sized and shaped surface elements. As a result of their simple morphology and the limited number of characteristic local surface structures, cubic metal oxide particles with a rock salt structure (such as MgO, CaO, CoO, MnO, NiO, and FeO) represent particularly well-suited model compounds to study such phenomena.…”