Exploiting Water as a Functional Surface to Create Inorganic Thin Films

Reactions at water surfaces are ubiquitous in Nature, where the structuring of water molecules and solvation process at water/air interfaces offers a unique environment that accelerates a range of reactions in comparison to when the same reactions occur in the gas phase or bulk water. However, the potential of using water as a functional surface for materials synthesis remains little explored.  This project will develop a sustainable and scalable process for generating inorganic thin films at the water surface. Previous methods of synthesising inorganic thin films have exploited solid substrates and surfactants (e.g. Langmuir monolayers). However, while valuable for many applications, it is often impossible to transfer the films to alternative substrates, surfactants are undesirable in many electronic and catalytic applications, and characterisation (e.g. TEM) can be challenging. Water, in contrast, is surfactant-free, flexible, and the films formed at its surface can be readily transferred to any selected substrate. Initial work will focus on the formation of thin films of biologically important minerals, where exciting preliminary results in the Kim lab have shown that centimetre sized CaCO3 and CoOOH thin films can be selectively deposited at the water surface by controlling the solution conditions, diffusion rates and interfacial tension. This system will be investigated in detail, where the structures and mechanism of formation of the thin films will be characterised using state-of-art techniques including time-resolved TEM and electron tomography, spectroscopic methods such as EELS, and in situ grazing angle XRD and scattering methods. The project will then be expanded to create thin films of functional metal oxides (ZnO, MnO2) and porous materials (MOFs), where the synthesis conditions will be optimised, and their structures will be fully characterised. Finally, the properties of these thin films in applications such as catalysis and gas absorption/ separation will be determined. This PhD project therefore offers excellent training in materials-centred science by combining synthesis, characterisation and property measurement.