Tuning the Interfacial Energetics in WO3/WO3 and WO3/TiO2 Heterojunctions by Nanostructure Morphological Engineering.

Nowadays, semiconducting heterojunction-based devices exhibit the best photocatalytic performance, with transition metal oxides such as tungsten (WO3) and titanium (TiO2) being the workhorse materials employed in these composites. Contrary to their bulk counterparts, WO3 and TiO2 nanostructures offer a huge versatility because their optoelectronic properties (i.e., energy levels) can be tuned by modifying their size, morphology, and composition, thus being, in principle, able to optimize the electron/hole injection barriers inside the device. However, this approach requires a deep fundamental knowledge of their structure-property relationships, which are extremely difficult to access from experiments. In this context, we employed state-of-the-art theoretical methods to determine the size and morphology dependency of the energetic alignment in WO3/WO3 and TiO2/WO3 nanostructure heterojunctions. Our results demonstrated that any type of alignment can be achieved by the proper choice of the nanostructures involved in the junction, while setting important rules for the design of efficient multicomponent devices.