Anagrafe della ricerca

Photon upconversion (UC), a process where two or more low-energy (NIR, Vis) photons are converted into one high-energy photon, has been receiving a lot of interest in many fields, from photovoltaics (PV) to bioimaging, medical therapies, 3D printing, photodetectors, but yet little in photocatalysis, although upconverted (recycled) photons could be exploited by a photocatalyst, improving its efficiency. Currently, most UC processes rely on Lanthanides-based nanoparticles (Ln NPs), which suffer from weak and narrow absorption, high thresholds (W/cm2 to kW/cm2), low abundance (most Ln deposits are outside Europe), and often undergo doping quenching effects. This calls for new UC systems. GREEN UP aims at developing a new generation of UC hybrid nanomaterials (NMs) relying on Triplet-Triplet Annihilation (TTA) to exploit solar light especially, but not exclusively, for photocatalysis. Compared with Ln NPs, such NMs have the great advantage of working with non-coherent and relatively low-intensity incident light (ca hundreds of mW/cm2), making them particularly promising for solar applications. In our new cutting-edge photocatalytic system, non-toxic metal-based quantum dots (QDs) will be adopted as sensitizers/enhancers. Organic moieties with tailored optical properties will be pre-selected as transmitters and annihilators/emitters by quantum mechanics. Nanostructured TiO2 will be adopted as support/receiver for solar photocatalysis. RU1 (Politecnico di Torino, POLITO) will produce by wet-chemistry methods (hot-injection) sensitizers with finely tailored and controlled properties, i.e. organic/inorganic interface, absorption range, etc. (Sustainable) template-free wet-chemistry methods based on pH control and/or use of ligands, followed by mild thermal treatment and/or supercritical CO2 extraction, will be adopted to obtain nanostructured TiO2. RU2 (Università di Cagliari, UNICA) will use mechanochemical methods to synthesize metal-based sensitizers under solvent-less conditions and to fabricate nanostructured TiO2 powders with suitable phase composition. RU3 (Università dell’Insubria, UINS) will carry out a computational screening on a set of organic moieties that are promising candidates to be used as transmitter and annihilator species by RU1 and RU2. Low-scaling methods such as KS-DFT and TD-DFT will be used, after being benchmarked using multireference wave function-based methods. On the most promising candidates, RU3 will evaluate the support effect on the annihilator properties. As a result, RU3 will identify the annihilator that more efficiently can be coupled with the sensitizer(s) in NIR-Vis and Vis-UV TTA-UC systems with TiO2 as support/receiver. The systems synthesized in GREEN UP will be evaluated according to these success criteria: i) range of upconverted photons and ii) enhancement of TiO2 photocatalytic activity towards CO2 reduction and degradation of emerging contaminants under solar light.