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).