Metal oxide heterostructured films with controlled architecture for enhanced photocatalytic properties

Photocatalytic processes possess favourable features that could address the various issues concerning environmental pollution. Among these issues, treatment of polluted wa- ter and water splitting for renewable hydrogen production are extensively studied but are still confronted to limitations for achieving high photocatalytic efficiencies that could be suc- cessfully commercialized. Investigations on powder materials have been widely reported for pollutant degradation/water treatment, but difficulties are prevailing in the re-usability of the material. Moreover, there is the need for finding a suitable heterostructured photo- catalyst that could provide better charge kinetics, an ultimate goal in photocatalyst design. Therefore, in this work, we have investigated thin-film based heterostructure photocatalysts, for improving the photocatalytic activity, especially towards pollutant degradation.
For this purpose, we have investigated the surface and interfacial properties of semiconductor/semiconductor (p-n type, NiO/ZnO) and metal/semiconductor (metal/n- type, RuO2/ZnO) heterostructures using systematic (step-by-step) interface studies, in order to gain knowledge regarding the influence of ZnO surface cleaning in the interfacial band bending, thereby analyzing the possibilities of their use as photocatalysts.
Furthermore, we have explored the electrical, optical and interfacial properties of ZnO nanorods (n-type) with NiO coating (p-type) by varying the NiO deposition parame- ters, to identify an optimized heterostructure. We examined the photocatalytic performance of these films for pollutant (Rhodamine B) degradation. In parallel, we explored the inter- action of water with heterostructured (NiO/ZnO) photocatalysts, to interpret the surface reactions and their influence on interfacial band bending, a strategy for understanding the heterostructured photocatalysts, which was not explored before.
Finally, we tested the ZnO nanorod film in an industrial research context for Rhodamine B degradation, to investigate the upscaling perspectives of the materials developed in this project.