Fine-tuning synthesis of fluorescent silver thiolate nanoclusters

Noble metal thiolate nanoclusters are a new class of nanomaterials with molecular-like properties such as high dispersibility and fluorescence in the visible and infrared spectral region, properties highly requested in biomedicine for imaging, sensing and drug delivery applications. We report on three new silver phenylethane thiolate nanoclusters, differing for slight modifications of the preparation, i.e., the reaction solvent and the thiolate quantity, producing changes in the nanocluster composition as well as in the fluorescence behavior. All samples, excited in the range 250-500 nm, emit around 400 and 700 nm differing in the emission maxima and behavior. The silver thiolate nanoclusters have been characterized by way of C, H, S elemental analyses and Thermal Gravimetric Analysis (TGA) to determine the nanocluster composition, Scanning Transmission Electron Microscopy (STEM) to investigate the nanocluster morphology and UV-Vis and fluorescence spectroscopy to study their optical properties

Extra-low dosage graphene oxide cementitious nanocomposites: a nano- to macroscale approach

The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on the properties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-D nanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake of nanoengineered cement-based materials. GO was characterized by X-ray Photoelectron Spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), and Raman spectroscopy. GO consisted of stacked sheets up to 600 nm × 800 nm wide and 2 nm thick, oxygen content 31 at%. The impact of GO on the fresh admixtures was evaluated by rheology, flowability, and workability measurements. GO-modified samples were characterized by density measurements, Scanning Electron Microscopy (SEM) analysis, and compression and bending tests. Permeability was investigated using the boiling-water saturation technique, salt ponding test, and Initial Surface Absorption Test (ISAT). At 28 days, GO-nanocomposite exhibited increased density (+14%), improved compressive and flexural strength (+29% and +13%, respectively), and decreased permeability compared to the control sample. The strengthening effect dominated over the adverse effects associated with the worsening of the fresh properties; reduced permeability was mainly attributed to the refining of the pore network induced by the presence of GO

Spectroscopic and Morphological Studies of Metal-Organic and Metal-Free Dyes onto Titania Films for Dye-Sensitized Solar Cells

We have investigated the spectroscopic behavior of three different sensitizers adsorbed onto titania thin films in order to gain information both on the electron transfer process from dye to titania and on the anchorage of the chromophore onto the semiconductor. We have examined by UV-Vis and fluorescence spectroscopy the widely used ruthenium complex cis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) (N719), the more recently developed organic molecular 3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid (D5), and a push-pull zinc phthalocyanine sensitizer (ZnPc). Three type of titania films with different morphology, characterized by SEM and FT-IR measurement, were considered: a mesoporous transparent film deposited by spin-coating (TiMS), a semiopaque film deposited by doctor-blade from mesoporous titania (TiMS_DB) and a semiopaque film deposited by doctor-blade form commercial P25 titania (P25_DB). The use of TiMS is responsible for the adsorption of a higher amount of dye since the mesoporous structure allows increasing the interfacial area between dye and titania. Moreover, the fluorescence emission peak is weaker when the sensitizers are adsorbed onto TiMS. These findings suggest that mesostructured films could be considered the most promising substrates to realize photoanodes with a fast electron transfer process

Realizzazione, mediante tecnica Plasma Enhanced Chemical Vapour Deposition (PE-CVD), di rivestimenti nanocompositi a base di titanio in matrice di diamond-like carbon, anti usura e anticorrosione, per applicazioni nell'industria meccanica e dell'utensileria da taglio

promotiedatum: 20-11-2014 � prom-id: 1159

Effect of Oxygen Plasma Pre-Treatment on the Surface Properties of Si-Modified Cotton Membranes for Oil/Water Separations

Hydrophobic and oleophilic Si-based cotton fabrics have recently gained a lot of attention in oil/water separation due to their high efficiency. In this study, we present the effect of O2 plasma pre-treatment on the final properties of two Si-based cotton membranes obtained from dip coating and plasma polymerization, using polydimethylsiloxane (PDMS) as starting polymeric precursor. The structural characterizations indicate the presence of Si bond on both the modified cotton surfaces, with an increase of the carbon bond, assuring the success in surface modification. On the other hand, employing O2 plasma strongly changes the cotton morphology, inducing specific roughness and affecting the hydrophobicity durability and separation efficiency. In particular, the wettability has been retained after 20 laundry tests at 40 °C and 80 °C, and, for separation efficiency, even after 30 cycles, an improvement in the range of 10–15%, both at room temperature and at 90 °C can be observed. These results clearly demonstrate that O2 plasma pre-treatment, an eco-friendly, non-toxic, solvent-free, and one-step method for inducing specific functionalities on surfaces, is very effective in enhancing the oil/water separation properties for Si-based cotton membranes, especially in combination with plasma polymerization procedure for Si-based deposition

Superhydrophobic fabrics for oil-water separation through a diamond like carbon (DLC) coating

The recent oil spill in the Gulf of Mexico has already caused, and is continuing to cause, significant global environmental issues and has severely impacted people's lives and natural resources. The ramifications of oil spill accidents highlight the difficulty of achieving effective oil-water separation, and the consequences of these accidents are harsh and long-term. In this work, we describe a convenient approach to fabricate cotton textiles with a hydrophilic coating, showing both superhydrophobic and superoleophilic properties. The surfaces are successfully prepared by one-step growth of a diamond-like carbon film onto the textiles via plasma-enhanced chemical vapour deposition and exhibit highly controllable, energy-efficient oil-water separation with high separation efficiency. The results have important implications for oil-absorption dynamics while repelling water completely. The present work suggests encouraging applications to marine spilt oil cleanup and other water-oil separation systems

Fabrication of a Flexible Si-cotton Filter Membrane for Efficient Hot Oil/Hot Water Separation

Increasing oily industrial waste water at room and high temperatures has become one of the most significant threats to the global ecosystem. Finding a suitable method for separating hot-oil/water pollution with an appropriate filter is highly necessary to effectively solve this problem. In this study, high-temperature oil/water separation was achieved using a silicon-modified textile (Si-cotton) as a filter, which was fabricated using polydimethylsiloxane (PDMS) solution as the precursor and through plasma polymerization. The plasma polymerization generated a uniform micro and nanoscale hierarchical structure on the Si-cotton surface. Furthermore, XPS and FT-IR analysis showed the lowering of the O/C ratio on the Si-cotton surface with respect to the pristine textile, and the presence of silicon on the Si-cotton surface after the plasma process. The results of these factors can be critical in making the final hydrophobic/oleophilic behaviour of the textile. More importantly, the Si-cotton membrane was tested for the separation process of hot oil/hot water mixture, which showed an acceptable efficiency even after fifteen separation cycles. The findings offered a two-step method, efficient and green, which was capable of working well even at a high temperature, to fabricate a flexible and scalable Si-cotton textile filter for reducing the necessity of additional and complicated cooling processes in the presence of high-temperature oil/water mixture