PhD Candidate: Tamez UDDIN
Date and place of defence: September 16, 2013 - Université Bordeaux 1, France.
Environmental issues such as air and water pollution has provided the impetus for sustained fundamental and applied research in the field of environmental remediation. With the huge advances performed in the field of nanoscience and nanostechnology, nanostructured semiconducting oxides (TiO2, ZnO or SnO2) have become very promising photocatalysts for their high catalytic activity, low cost, and environmental friendliness. However, some limitations to achieve high photocatalytic efficiency in some cases have been pointed out due to the quick recombination of the charge carrier. Nonetheless, it was recently been shown that the photocatalytic performances can be greatly improved by developing metal oxide-based heterostructures or composites.
This project aims at developing new prospects in this field by designing Janus nanoparticles combining two different metal oxide materials with different bandgaps or by the combination of an oxide materials and a metal (such as silver) to define a vectorial charge separation. The oxide particles will be synthesized using different solution routes as sol-gel process and metal coating will be obtained by reduction of metal salts. The texture, structure and morphology of the resulting particles will be characterized by various scattering (XRD, light diffusion), sorption (BET, mercury intrusion porosimetry) and microscopy (SEM, TEM) techniques. The alignment of the energy levels (valence band offset, conduction band offset) will be investigated in the novel metal oxide heterostructures by photoemission spectroscopies (XPS, UPS) to evaluate the energetic characteristics of the electron/hole transfer. The main objective is to prove the principle of the approach proposed and to determine the phenomenon occurring at the interfaces in the different systems studied. Photocatalytic properties of these particles will be then studied and interpreted on the basis of the previous measurements.
UB1 - ISM (Institute for Molecular Science, Bordeaux) Sol-gel synthesis of metal semi-conducting oxide nanoparticles; chemical modification of semi-conducting oxide surfaces
TUD - Surface Science (Darmstadt): vacuum technique expertise; structural characterization expertise in surface science
MERCK Darmstadt Germany