SURFACE PROPERTIES AND ELECTRONIC STRUCTURE OF FUNCTIONAL OXIDES Our research is concerned with exploring the relationship between the surface properties and the electronic structure of functional metal oxides. We are interested in two main classes of materials, both with applications in the field of solar energy conversion: transparent conducting oxides (TCOs); and oxides capable of inducing photocatalytic reaction such as the splitting of water into hydrogen and oxygen or the degradation of organic pollutants. Single crystal TCOs are grown in a ultrahigh vacuum (UHV) apparatus unique within the UK which uses atomic beams of metals and oxygen to prepare materials of the highest quality. The films fabricated in this way are characterised by a range of techniques including high resolution transmission electron microscopy, atomic force and scanning tunnelling microscopy, high resolution diffraction and transport measurements. A range of electron spectroscopic techniques including hard and soft X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy are used to study electronic structure. We also collaborate with Professor Kevin Smith at the University of Boston in the measurement of X-ray absorption and emission spectra, which provide decisive evidence about details of the bonding in simple inorganic solids. Extensive use is made of national and international synchrotron radiation facilities including Diamond (UK), the ESRF (Grenoble, France), ELETTRA (Trieste, Italy), MaxLab (Lund, Sweden), NSLS (Berkeley, USA) and NSLS (Brookhave, USA). We are also major users of the ultrahigh resolution XPS facility at the Daresbury Laboratory. Underpinning the UHV growth studies we are also involved in more conventional solid state synthesis, with characterisation of the ceramic compounds by X-ray diffraction and magnetic susceptibility and conductivity measurements. Indium oxide on cubic ZrO2 viewed by scanning electron microscopy (left) and atomically resolved high resolution transmission electron microscopy (right)
Surface energies control the self-organisation of oriented In2O3 nanostructures on cubic zirconia K H LZhang, Aron Walsh, C R A Catlow, V K Lazarov and R G Egdell Nano Letters 2010 10 3740-3746 A critical evaluation of the mode of incorporation of nitrogen in doped anatase photocatalysts F E Oropeza, J Harmer, R G Egdell and R G Palgrave Physical Chemistry Chemical Physics 2010 12 960-969 An x-ray spectroscopic study of the electronic structure of CuCrO2 T Arnold, D J Payne, A Bourlange, J P Hu, R G Egdell, L F J Piper, L Colakerol, A DeMasi, P-A Glans, T Learmonth and E Smith, D O Scanlon, A Walsh, B J Morgan and G W Watson Physical Review B 2009 79 07512/1-9 Surface structure and electronic properties of In2O3(111) single crystal thin films grown on Y-stabilised ZrO2(111) K H L Zhang, D J Payne, R G Palgrave, V K Lazarov, W. Chen, A T S Wee, C F McConville, P D C King, T D Veal, G Panaccione, P Lacovig and R G Egdell Chemistry of Materials 2009 21 4353-4355 Surface electron accumulation and the charge neutrality level in In2O3 P D C King, T D Veal, D J Payne, A Bourlange, R G Egdell and C F McConville Physical Review Letters 2008 101 116808/1-4 The nature of the bandgap in In2O3 revealed by first-principles calculations and X-ray spectroscopy A Walsh, Juarez L F Da Silva, S-H Wei, C Körber, A Klein,L F J Piper, A DeMasi, K E Smith, G Panaccione, P Torelli, D J Payne, A Bourlange and R G Egdell Physical Review Letters 2008 100 167402/1-4 Electronic origins of structural distortions in post-transition metal oxides: experimental and theoretical evidence for a revision of the lone pair model D J Payne, R G Egdell, A Walsh, G W Watson, J Guo, P A Glans, T Learmonth and K E Smith Physical Review Letters 2006 96 157403/1-4 Manipulation of atoms across a surface at room temperature T W Fishlock, A Oral, R G Egdell and J B Pethica Nature 2000 404 743-746