Large-scale synthesis of inorganic colloidal TiO2@WO3-x nanoheterostructures based on multicomponent semiconductor (TiO2)-plasmonic (WO3-x) heterojunctions. The syntheses of these nanoheterostructures are realised in an aqueous environment using microwaves, an extremely efficient, fast, homogeneous and modular in core-localised dielectric heating mode in several simultaneous reaction vessels, which allows very fast synthesis times, high synthesis temperatures even in an aqueous environment and easy scalability. These nanoheterostructures maximise the photochemical (and non-photochemical) mechanisms activated in the UV and VIS-NIR spectral range. They have proven to be of interest as active material in IR-selective electrochromic devices; photochromic material already tested in technical textiles; chemiresistors for gas sensing and especially as photocatalysts in liquid-phase photooxidation reactions. The use of widely available and inexpensive chemical elements, water as the main reaction solvent, and the rapidity of synthesis frame the entire process in the fields of green chemistry and process sustainability.
Large-scale (gram material) production by microwave technique of semiconductor-plasmonic TiO2@WO3-x nano-heterostructures with morphological and compositional control on a single heterostructure scale. Such heterostructured materials are attracting increasing interest in the scientific community, although they often require the presence of (rare and expensive) noble metals as plasmonic components. In contrast, the heterostructure discussed here utilises a common semiconductor in a non-stoichiometric form (WO3-x), which therefore takes on a metallic character. The nanostructures are generated in an aqueous environment, where they retain excellent colloidal stability, by means of a modular microwave system involving many dozens of parallel syntheses. This synthetic approach bypasses the conventional limitations of massive scaling-up, making the production of these photo-active 'nano-inks', which can be applied in diverse fields, more competitive. In addition, the possibility of functionalising large-area surfaces with wet and user-friendly techniques to produce nano-functionalised surfaces without geometry constraints is a further, not insignificant advantage.