Porous, Nanostructured and Amorphous Materials
This theme concerns solids which possess useful functional properties (e.g. electrical, optical, catalytic, biological) stemming from their porosity and/or atomic structure. Our activities encompass the synthesis of novel materials (including glasses, nanocrystals, nanocomposites, polymer solar cells and MOFs), the experimental characterisation of their atomic- and nano-scale structure and the modelling of these structures and associated properties (Fig 1 and 2).
One of the most challenging contemporary problems for materials characterisation is to collect sufficiently comprehensive experimental data sets from complementary techniques to be able to describe accurately and unambiguously the structure of amorphous and nanostructured materials, and to follow how their structure changes with processing. We have a wide range of laboratory-based materials characterisation equipment in-house (e.g. XRD, SEM, N2 Physisorption at 77K, Raman etc). However, to understand these complex materials at the level required demands the use of a range of advanced modern characterisation methods. The atomic scale probes available to us are X-ray absorption spectroscopy, and X-ray and neutron diffraction. Porosimetry and analogous techniques such as small angle scattering allow us to probe length scales approaching microns. Our work relies on access to world-class international facilities such as the ISIS and the ILL neutron sources and the Diamond, ESRF and Elettra synchrotron X-ray sources. The use of advanced computer modelling and simulation methods is integrated with the experimental work, creating a powerful combination; direct comparison between experiment and simulated model is now possible (Fig. 3).
|Fig. 1:An HRTEM image of a single FeCo
nanocrystal embedded in a silica aerogel matrix
|Fig. 2: a model of a silicate sol-gel glass|
Fig 3: Atomistic model of mesoporous MnO2 (1 million atoms) which can be compared directly to HRTEM images; MnO2 is used as a host lattice for Li-ion batteries (Reprinted with permission from The Journal of the American Chemical Society, Copyright American Chemical Society 2009). Full reference: Predicting the Electrochemical Properties of MnO2 Nanomaterials Used in Rechargeable Li Batteries: Simulating Nanostructure at the Atomistic Level, Sayle TXT, Maphanga RR, Ngoepe PE and Sayle DC, J. Am. Chem. Soc., 131, 6161-6173, 2009.