Charge Separation in Graded Metal Oxide Nanocomposites

Wider research context:
The photogeneration of charge carriers inside oxide nanostructures and the resulting surface reactions are key steps in energy conversion, catalysis and environmental science. Current materials systems have severe efficiency and selectivity limitations. There is an urgent need to improve our understanding of such architectures and to develop innovative concepts in materials design.

Objectives:
This research program focusses on a novel class of nanocomposites involving alkaline earth oxides (BaO/SrO) and titania (TiO2). It will include nanostructured ferroelectric perovskites (BaTiO3/SrTiO3) derived from such composites via thermal annealing. We will investigate fundamental light-induced processes (charge separation and adsorption) and ferroelectric contributions to enhance charge separation. Two different materials systems will be developed: (i) Nanoparticle powders with high specific surface areas and tunable densities; (ii) Layered nanohole films with controlled porosity, composition, and doping, supported on 2D substrates. The influence of spontaneous polarization on the surface chemistry and separation of photogenerated charge carriers will be investigated in the metal oxide grains and the compositionally graded interface layers.

Level of originality:
With this integrated approach, we aim at an unprecedented coherent description of the photo-generation, separation and chemical utilization of charge carriers in composite nanostructured metal oxides. Apart from key insights that are important for the rational development of photoactive materials for energy conversion and photocatalysis, we believe that this work will be highly influential for materials science activities that focus on the exploitation of spontaneous polarization effects for sensors, piezoelectric energy harvesters and for light induced processes in functional electroceramics.