The water/oxide interface, and the molecular processes that happen there, regulate everything from environmental chemistry and the sequestration of CO2 to the cohesion of man-made structures. The properties of individual surface sites govern reactivity, so probing chemistry at this level is necessary to better understand natural processes, and to ultimately improve technologies where this interface plays a central role. In this project, we take a radically new approach to investigate the water/oxide interface at the most fundamental, the atomic, scale: we have found a way to integrate bulk liquid water into ultrahigh vacuum (UHV) setups, where an arsenal of highly-developed techniques is available to investigate surfaces. This provides the opportunity to accurately determine fundamental quantities that were hitherto inaccessible, and to obtain clear-cut experimental results for interpreting and predicting molecular-scale processes. In this project, we seize this opportunity to develop novel measurement concepts, and apply them to minerals. Following a broad work plan we will: measure the surface tension of neat water and the surface free energies of solids with unprecedented purity; devise a method to determine, site-by-site, the intrinsic proton affinity, the fundamental property that determines the point of zero charge of oxides in solutions, and their Brønsted acidity in gas-phase reactions; investigate, at the atomic scale, how liquid water affects surface structure, and how oxides become hydroxylated, dissolve, and ‘age’; discover how ice nucleates on the mineral aerosol surfaces that are crucial in cloud formation; study how dissolved CO2 reacts with natural minerals, which affects the global carbon cycle; address the hydrated oxides that form the basis of cements in concrete. While this project focuses on providing a fresh view on environmentally-relevant chemistry, we also show how our approach can make an impact in a much wider range of areas.

Fluid flows through porous media with morphology modifications are ubiquitous across nature and industry, from the melting and refreezing of snow to the migration of carbon dioxide in underground aquifers, from phase-change materials in energy storage systems to the formation of sea ice. A key property of media experiencing morphology variations is that the modifications of the pore structure relate to the local flow conditions, which in turn are affected by the geometry of the porous matrix. Despite their importance and pervasiveness, measuring and modelling flow transport and medium evolution in these systems remains challenging, due to the multiway coupling, multiscale nature and feedback mechanisms. The objective of this project is to shed new light on the evolution of porous multiscale systems characterised by flow-induced morphology modifications. Three classes of media with increasing levels of complexity (porous media with phase-change, reactive media and reactive media with phase-change) will be investigated in well-defined and controlled flow configurations. To tackle these problems, we will employ in a complementary manner a combination of numerical simulations, laboratory experiments and theoretical modelling. We will use these findings in a multiscale modelling framework where the large-scale and long-term flow behaviour is predicted by simple models that are fed with the results of high-resolution numerical and laboratory experiments. This project aims at a true scientific breakthrough: we want to gain a quantitative understanding of flow transport and medium evolution in porous media with morphology modifications, unraveling a number of physical mechanisms that will allow the prediction and control of these complex systems.