Giovedì 12 settembre 2019
Sala Seminari, Piano I, Edificio U5 – via Roberto Cozzi 55, Milano
Relatore: Francesco Parrino - Dipartimento di Ingegneria Industriale (DII), Università di Trento, via Sommarive 9, 38123, Trento
Titolo: The role of nitrate ions on the photocatalytic synthesis of high-value added compounds
Abstract. Nitrate ions have been often considered inert species in irradiated photocatalytic suspensions. In fact, photocatalytic degradation of various pollutants generally proceeds with similar kinetics regardless of the presence of nitrate ions. However, the joint use of EPR and UV-vis spectroscopy shows that nitrate radicals are formed by hole induced oxidation of nitrate ions in irradiated TiO2 suspensions. Known as "nocturnal radicals", nitrate radicals are photolabile species which induce oxidation reactions of great importance for the self cleaning ability of the atmosphere during night time. The lifetime of nitrate radicals is, however, enough to induce useful photocatalytic reactions for the synthesis of high value added compounds. Their role is evidenced, for instance, in the photocatalytic production of elemental bromine and in the nitration of model alkene compounds. These results not only allow deeper understanding of photocatalytic processes, but open the route to new green photocatalytic syntheses and to new insights in the field of atmospheric chemistry.