Cauliflower-like CeO2–TiO2 hybrid nanostructures with extreme photocatalytic and self-cleaning properties

In recent years, heterogeneous photocatalysis has gained enormous interest due to increasing concerns about environmental pollution. Here we propose a facile approach to synthesize cauliflower-like CeO2–TiO2 hybrid structures by magnetron reactive sputtering, exhibiting an extremely high photocatalytic activity. While heating and air-quenching of the sputter deposited TiO2 thin film (first layer) triggered the formation of a nanocrack network, the second heat-treatment led to transformation of the CeO2 film (second layer) into CeO2 nanoclusters (NCs). We attribute the resulting high photocatalytic activity to the confined structure of the CeO2 NCs and the CeO2–TiO2 interface, which allows Ce3+/Ce4+ dynamic shifting. In addition to high photocatalytic activity in an aqueous medium, the prepared CeO2–TiO2 hybrid structures exhibited significant self-cleaning properties in air (non-aqueous).