Synthesis and Nanostructure Characterization of New Aero‐ CeO2${\rm CeO}_2$ /(Zn) TiO2${\rm TiO}_2$  Composite Networks for (photo‐)Catalytic Applications

Photocatalytic reactions hold great promise for using the abundant solar energy for green energy production via water splitting to gain H2$H_2$ as well as purifying air from pathogens or waste water from organic pollutants. To initiate these reactions using visible light, a catalytic material is required, often based on compounds of one or more oxide semiconductors, which necessitates the control of material production and the designed architecture with respect to the targeted application. In this contribution, we demonstrate a wet chemical synthesis approach to produce a highly macroporous 3D network structure of oxide semiconductors CeO2${\rm CeO}_2$ /(Zn) TiO2${\rm TiO}_2$ which is hierarchically designed by interconnecting hollow microscale tetrapodal structures with nanoscale functionalization using a core/shell geometry. Transmission electron microscopy was used to identify the present crystalline structures and chemical properties of the components before and after annealing. Before annealing, a variation of the oxidation state is present in the nanocrystalline CeO2${\rm CeO}_2$ component, while during further oxidation the formation of a ternary particle network composed of heterojunctions between CeO2${\rm CeO}_2$ , rutile TiO2${\rm TiO}_2$ and Zn2TiO4${\rm Zn}_2{\rm TiO}_4$ crystalline particles is evidenced. Producing such a combination of materials on a rigid and macroporous framework could show great potential as a catalyst for liquid‐ or gas phase applications.