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This work focuses on the photocatalytic performances and antibacterial activity of TiO 2 and Au/TiO 2 nanosystems. While the former are obtained by a sol-gel route, the latter are synthesized by an innovative hybrid RF-sputtering/sol-gel approach, followed by ex situ annealing in air up to 600 • C. Important information on nanoparticle size, shape and distribution is obtained by the combined use of glancing incidence x-ray diffraction (GIXRD) and field emission-scanning electron microscopy (FE-SEM). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of the azo-dye Plasmocorinth B and their antibacterial activity in the elimination of Bacillus subtilis are illustrated and discussed in comparison with films obtained from standard Degussa P25 powders. The obtained results show a significant dependence of the functional performances on the system's compositional, structural and morphological properties. In particular, the dispersion of gold nanoparticles on the TiO 2 matrix has a beneficial influence on the azo-dye photodegradation, whereas the antimicrobial activity of Au/TiO 2 films is retarded with respect to pure TiO 2 .

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The present study, focused on the sol-gel synthesis of rare-earth-doped zinc oxide, highlights the crucial points involved in the design and development of ZnO/Eu nanosystems with peculiar and easily tunable photophysical properties. ZnO nanopowders containing different europium amounts were prepared starting from zinc and europium acetate salts as the sol precursors. The densification process and the evolution of the structural-optical properties were studied as a function of annealing performed in air between 100 and 1000°C. The microstructure and composition of the samples and their dependence on the synthesis procedure were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, whereas the emission properties were studied by photoluminescence spectroscopy in the energy and time domains as a function of the structural evolution. Crystalline ZnO powders in the wurtzite structure were formed after heat treatment at 400°C, with an average nanocrystal size of ca. 20 nm. Stronger annealing conditions allowed a more extended densification of the oxide-based network and the removal of most -OH groups but also promoted the crystallization of Eu 2 O 3 at 800°C. The most intense emission bands around 600 nm due to Eu 3+ transitions were clearly observed in the annealed samples (T g 600°C). Interestingly, the observed overlap of the typical Eu 3+ red emission with the characteristic green luminescence of the nanostructured ZnO matrix can be synergistically exploited for single or multicolor emission through the proper choice of the excitation wavelength.

We report the study of two-dimensional graphitic carbon nitride (GCN) functionalized with copper single atoms as a catalyst for the reduction of CO2 (CO2RR). The correct GCN structure, as well as the adsorption sites and the coordination of the Cu atoms, was carefully determined by combining experimental techniques, such as X-ray diffraction, transmission electron microscopy, X-ray absorption, and X-ray photoemission spectroscopy, with DFT theoretical calculations. The CO2RR products in KHCO3 and phosphate buffer solutions were determined by rotating ring disk electrode measurements and confirmed by 1H-NMR and gas chromatography. Formate was the only liquid product obtained in bicarbonate solution, whereas only hydrogen was obtained in phosphate solution. Finally, we demonstrated that GCN is a promising substrate able to stabilize metal atoms, since the characterization of the Cu-GCN system after the electrochemical work did not show the aggregation of the copper atoms.

We describe the synthesis, computational analysis, photophysics, electrochemistry and electrochemiluminescence (ECL) of a series of compounds formed of two triphenylamines linked by a fluorene or spirobifluorene bridge. The phenylamine moieties were modified at the para-position of the two external rings by electron-withdrawing or electron-donating substituents. These modifications allowed for fine-tuning of the photoluminescence (PL) and ECL emission from blue to green, with an overall wavelength span of 73 (PL) and 67 (ECL) nm, respectively. For all compounds, we observed a very high PL quantum yield (79-89%) and formation of stable radical ions. The ECL properties were investigated by direct annihilation of the electrogenerated radical anion and radical cation. The radical-ion annihilation process is very efficient and causes an intense greenish-blue ECL emission, easily observable even by naked eye, with quantum yield higher than the standard 9,10-diphenylanthracene. The ECL spectra show one single band that almost matches the PL band. Because the energy of the annihilation reaction is higher than that required to form the singlet excited state, the S-route is considered the favored pathway followed by the ECL process in these molecules. All these features point to this type of molecular system as promising for ECL applications.

The present work is devoted to the preparation of Ag/TiO(2) nanosystems by an original synthetic strategy, based on the radio-frequency (RF) sputtering of silver particles on titania-based xerogels prepared by the sol-gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF-sputtering, whose combination enables the obtainment of a tailored dispersion of Ag-containing particles into the titania matrix. In addition, the system's chemico-physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600 degrees C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), secondary ion mass spectrometry (SIMS), glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), electron diffraction (ED), high-angle annular dark field scanning TEM (HAADF-STEM), energy-filtered TEM (EF-TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo-dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties.