Core-shell structures and nanovoids

The coating of photocatalytically active TiO₂ nanoparticles with ultrathin layers of different metal oxides (silica, alumina) is done to investigate mechanisms of photocatalytic processes. These materials possibly enhance the photocatalytic activity by affecting the adsorption/desorption equilibria of reactants and the deactivation behaviour of Pt/titania, by changing the conduction of charge carriers within the material and by reducing the agglomeration of nanoparticles. The design of nanoporous layers via calixarene templates can further provide size selection of reactants.

The thickness of the layers should be up to 1 nm and can be deposited by atomic layer deposition (ALD) and several wet chemical synthesis techniques. These core@shell materials are analyzed via several spectroscopic techniques, including photoluminescence to investigate charge carrier behaviour. The thickness of the layers is  determined via transmission electron microscopy (TEM), including energy-dispersive X-Ray spectroscopy (EDX), and small angle X-Ray scattering (SAXS).

Photocatalytic experiments and adsorption equilibria are conducted with
differently sized and charged reactants in protic and aprotic solvents to investigate adsorption behaviour, size selection and charge carrier dynamics. Hydrogen evolution reactions (HER) with platinum as a co-catalyst might give indications about the influence of the underlying metal oxide on the co-catalyst and charge carrier dynamics.