The critical role of intragap states in the energy transfer from gold nanoparticles to TiO2

Cathodoluminescence spectroscopy is profitably exploited to study energy transfer mechanisms in Au and Pt/black TiO2 heterostructures. While Pt nanoparticles absorb light in the UV region, Au nanoparticles absorb light by surface plasmon resonance and interband transitions, both of them occurring in the visible region. The intra-bandgap states (oxygen vacancies) of black TiO2 play a key role in promoting both hot electron transfer and plasmonic resonant energy transfer from Au nanoparticles to the TiO2 semiconductor with a consequent photocatalytic H2 production increase. An innovative criterion is introduced for the design of plasmonic composites with increased efficiency under visible light

Silica SHB chiral Pc-L* copper complexes for halogen-free solvent cyclopropanation reactions

The grafting of the preformed Pc-L* (pyridine containing macrocyclic ligands) copper(I) complexes on different ordered and non-ordered silicas, and their use, under heterogeneous batch conditions, as catalysts for the olefin cyclopropanation are reported. High yields (up to 99%), good recyclability in halogen-free solvent reactions were obtained, together with negligible copper leaching (0.1% of total copper)

Influence of TiO2 electronic structure and strong metal-support interaction on plasmonic Au photocatalytic oxidations

Aiming at understanding how plasmonic reactions depend on important parameters such as metal loading and strong metal-support interaction (SMSI), we report the plasmonic photodegradation of formic acid (FA) under green LED irradiation employing three TiO2 supports (stoichiometric TiO2, N-doped TiO2, black TiO2) modified with Au nanoparticles (NPs) 3-6 nm in size. The rate of FA photo-oxidation follows different trends depending on Au loading for stoichiometric and doped Au/TiO2 materials. In the first case, the only contribution of hot electron transfer produces a volcano-shaped curve of photoreaction rates with increasing the Au loading. When TiO2 contains intra-bandgap states the photoactivity increases linearly with the Au NPs amount, thanks to the concomitant enhancement produced by hot electron transfer and plasmonic resonant energy transfer (PRET). The role of PRET is supported by Finite-Difference Time-Domain simulations, which show that the increase of both Au NPs inter-distance and of SMSI enhances the probability of charge carrier generation at the Au/TiO2 interface

SURFACE ORGANOMETALLIC CHEMISTRY - REDUCTIVE CARBONYLATION OF SILICA-SUPPORTED RUCL3.3H2O

The reductive carbonylation of silica-supported RuCl3 \ub7 3H2O was investigated. This physisorbed salt reacts with CO at 25-50\ub0C to form the silica-bound species [Ru(CO)2Cl2(HOSi{A figure is presented})2], which is converted into the silica-bound tricarbonyl species [Ru(CO)3 Cl2(HOSi{A figure is presented})] when the temperature is raised to 100\ub0C. The surface species may be extracted with suitable donor solvents at room temperature. With [Ru(CO)3Cl2(HOSi{A figure is presented})], extraction using acetone followed by recrystallization from dichloroethane/ pentane affords [Ru(CO)3Cl2]2 in high yield. The dimer sublimes directly from the surface upon carbonylation at 180\ub0C. Liberated HCl probably inhibits further reduction. However, starting from physisorbed [{Ru(CO)3Cl2}2], the species [Ru2(CO)6Cl 4(H2O)] is formed on the surface in the presence of CO + H2O at 100\ub0C. Only traces of [{Ru(CO)3Cl2}2] and clusters such as [Ru3(CO)10Cl2] and [Ru3(CO)12] sublime under these conditions