Search results for " (photo)catalysis"
showing 10 items of 166 documents
The influence of Al doping on the photocatalytic activity of nanostructured ZnO: The role of adsorbed water
2018
Abstract Al doped ZnO nanoparticles (labeled as x% A-ZnO, x = 0.0, 0.5, 1.0, and 1.5) were synthesized by a simple sol-gel method, characterized and tested as photocatalysts for the degradation of a model compound under UV-light irradiation. Diffuse reflectance spectroscopy (DRS) and photoelectrochemical analysis have been performed to evidence their optical and electronic behavior. The structural features of the powders were highlighted by means of specific surface area (SSA) analysis, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopy. Al doping results in enhanced photocatalytic activity of the modified powders with respect to pure ZnO. In particular, the h…
Preparation of Sm-loaded brookite TiO2 photocatalysts
2011
Abstract Pure and Sm-loaded brookite nanoparticles and thin films were prepared using TiCl4 as precursor of TiO2. The samples were characterized by X-ray diffraction (XRD), specific surface area (SSA) determination, diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements. The photocatalytic activity of the powders was investigated by employing the photodegradation of 4-nitrophenol in a liquid–solid system whilst the photoreactivity of the films was tested by evaluating the rate of degradation of 2-propanol in a gas–solid system. Loading with Sm resulted in a significant improvement of the photoreactivity of brookite and the beneficial effect was attributed to an incre…
Enhanced Solar Light Photocatalytic Activity of Ag Doped TiO2–Ag3PO4 Composites
2020
Composites comprised of Ag3PO4 and bare TiO2 (TiO2@Ag3PO4) or silver doped TiO2 (Ag@TiO2&ndash
N-TiO2 Photocatalysts highly active under visible irradiation for NOX abatement and 2-propanol oxidation
2013
N-doped TiO2 powders were prepared by two different sol-gel methods. Samples were characterised by X-ray diffraction (XRD), BET specific surface area measurements (SSA), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR). XPS measurements revealed a signal at 400 eV assignable to nitrogen in the form of Ti-N-O. EPR signals are attributed to molecular NO trapped with cavities/defects possibly interacting with oxygen vacancies. The photocatalytic activity under UV and visible light was determined following the abatement of NOx and the photodegradation of 2-propanol in gas-solid systems. N…
Heteropolyacids supported on boron nitride and carbon nitride for catalytic and catalytic photo-assisted alcohol dehydration
2021
Keggin H3PW12O40 (PW12) and Wells-Dawson H6P2W18O60 (P2W18) heteropolyacids (HPAs) are photo(catalysts) for various acid-promoted and redox catalytic reactions. Their activity increases if they are deposited on certain supports as metal oxides or carbon materials. Although the surface area and acid-base interactions of the HPAs with supports are considered as key factors for the performance of the binary material, the role of the local structure changes in the HPAs upon their immobilization on solids must be also of primary importance, directly affecting both acidity and photoredox properties. Here, the (photo)catalytic performance of Keggin and Wells-Dawson heteropolytungstates supported o…
Influence of sol counter-ions on the visible light induced photocatalytic behaviour of TiO2 nanoparticles
2014
Titanium dioxide (TiO2) nanoparticles are attracting increasing interest because of their superior photocatalytic and antibacterial properties. Here, aqueous titanium oxy-hydroxide sols were made, using a green synthesis method, from the controlled hydrolysis/peptisation of titanium isopropoxide. Three different mineral acids were used to peptise the sol (HNO3, HBr and HCl), and provide counter-ions. The influence of nitrate or halide sol counter-ions on size distributions of the starting sols were measured via photon correlation spectroscopy (PCS). Semi-quantitative phase composition analysis (QPA), on the gels thermally treated at 450 and 600 degrees C, was carried out via Rietveld refine…
Experimental evaluation of the durability of innovative cementitious coatings: photocatalytic activity and colour
2012
Today, in a world context characterized by high pollution levels and increasingly limited natural resources, even in the building sector, focusing on environmental issues, through energy saving and a more rational use of these resources, both during construction and management, is fundamental. An important contribution in this direction is given by the knowledge of the durability of products and building components, especially when innovative products are applied and no information are available on the reliability and service life. The research concerns the evaluation of the durability of cement-based photocatalytic coatings ("rasanti" in the Italian diction), containing different types of …
A Dialysis Photocatalytic Reactor for the Green Production of Vanillin
2020
In the present work, dialysis was used to recover vanillin while being produced by partial photocatalytic oxidation of ferulic acid in an aqueous solution at ambient temperature. The relatively high value of the permeate flux through a dense polyether-block amide membrane allowed continuously extracting vanillin from the reacting solution, thus avoiding its successive oxidation. The rate of vanillin formation was improved, compared to other reactor configurations, because intermediate compounds permeated from the reacting solution and did not hinder the reaction, while ferulic acid permeated in the opposite direction to partially replenish the reactor with the substrate. The photocatalytic …
Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals
2015
Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a…