Effect of titanium dioxide crystalline structure on the photocatalytic production of hydrogen

The effect of the crystalline phase of TiO 2 (anatase, rutile and brookite) on its photocatalytic activity in hydrogen production from methanol-water vapours has been investigated by testing a series of both home-made and commercial TiO 2 photocatalysts, either bare or surface-modified by deposition of a fixed amount, i.e. 1 wt%, of platinum as co-catalyst. For all of the TiO 2 samples the rate of hydrogen production increased by one order of magnitude upon Pt deposition, because of the ability of Pt to enhance the separation of photoproduced electron-hole pairs. Under irradiation in the 350-450 nm wavelength range, brookite and anatase showed similar photoactivities, both superior to that of rutile. By contrast, rutile, possessing a narrower band gap, was active also under visible light (λ > 400 nm), whereas no hydrogen evolution was observed with anatase and brookite under such conditions. Surface area proved to be a key parameter, strongly influencing photoactivity. However, as the particle size became ultra-small, the semiconductor absorption edge was blue-shifted because of size quantisation effects, with a consequent decrease in hydrogen production rate due to the smaller portion of incident photons absorbed by the photocatalyst. © The Royal Society of Chemistry and Owner Societies 2011

Tools for quality assurance and assessment of Agricultural Engineering programmes, TUNING subject-area lines and disappearing/rare knowledge in Italy

The quality assurance process applied by Italian State University institutions, in order to achieve some level of internal quality control or assessment for the offered study programmes, is established in the funding criteria of the Ordinary Financing Fund (FFO), decided by the National Committee for the Evaluation of the University System (CNVSU). In most Italian Universities the quality assurance and assessment procedure of the study programmes starts with a report, written by a specific committee, that carries out an internal assessment, by which the strong and weak points of the study programme and the related causes are focused. The quality assurance and assessment procedure appoints three autonomous and independent assessors, who have the task of carrying out an external assessment of the degree study programmes and publishing an evaluation report. In Italian Universities the Faculty Assembly holds the tasks of: setting the education and research objectives and evaluating the success in satisfying them; providing, monitoring and enhancing the intellectual and material resources; demonstrating high standards to external assessors and taking into account their reports; co-operating with representatives of professional bodies for carrying out the examination for accessing the professional activity; planning new programme specifications; monitoring student career progression. The Degree Study Programme Assembly holds the task of approving the study programmes of individual students. Moreover, in Italy the Ministry of Education, University and Research, the region administration and the University academic bodies hold the responsibility of: overseeing academic quality and standards; managing the University education and research strategy; overseeing the development and management of quality assurance procedures; approving Faculty recommendations related to the proposal of new study programmes and/or the discontinuation of existing ones. In Italy the Standard Assessment procedure for students is based on the following principles: students can take an examination for a specific course as many times as they wish; examiners and assessors are appointed by the Faculty Dean, while a specific committee is responsible for University examinations; students are finally examined for their thesis by a Faculty committee. Italian Universities offer a Code of Practice for education and research, which is included in several laws and decrees, that set out the guidelines which must be followed in managing a study programme and designing the related courses. In Italy the typical degree profiles in Agricultural/Biosystems Engineering, for the three study levels, are offered by five University Faculties of Agriculture. As regards the status of rare/disappearing knowledge in Agricultural/Biosystems Engineering studies in Italy, it is needed to focus especially on the following subjects: historical farm buildings and new purposes; agritourism; agricultural museums. In Italy several actions try to protect and revitalise the historical farm buildings and, therefore, create jobs and profit for the local community. The destiny of Italian old buildings mainly depends on the implementation of integrated rural development plans, taking into account the landscaping and environmental functions of farms. Converting historical farm buildings or houses into B&B lodges, farm hotels and restaurants generates a new farm activity called agritourism. In Italy, where more than 1600 farm resorts are available, incentives provided for agritourism have been successful in preventing the depopulation of the countryside. A historical farm building can be converted into an agricultural museum. More than 500 agricultural museums are available throughout Italy

The Role of Water in the Photocatalytic Degradation of Acetonitrile and Toluene in Gas-Solid and Liquid-Solid Regimes

Photocatalytic degradation of acetonitrile and toluene was carried out both in gas-solid and in liquid-solid regimes by using commercial TiO2 samples ( Merck and Degussa P25). The investigation was mainly aimed to study the influence of water present in the reaction environment on the mechanism and degradation rate of two probe molecules. In gas-solid regime, the reacting mixture consisted of toluene or acetonitrile, oxygen, nitrogen, and water vapour. The main degradation product of toluene was CO2 with small amounts of benzaldehyde. In the presence of water vapour, the activity of TiO2 Merck remained stable but greatly decreased if water was absent. TiO2 Degussa P25 continuously deactivated, even in the presence of water vapour. With both catalysts, the photodegradation products of acetonitrile were CO2 and HCN; the activity was stable and was independent of the presence of water vapour in the reacting mixture. The production of HCN represents a drawback of acetonitrile photocatalytic degradation but the elimination of HCN is not actually a problem. In liquid-solid regime, the main intermediates of toluene photodegradation were p-cresol and benzaldehyde; traces of pyrogallol and benzyl alcohol were also found. Benzoic acid, hydroquinone, and trans, trans muconic acid were detected only when TiO2 Merck was used. The photodegradation products of acetonitrile were cyanide, cyanate, formate, nitrate, and carbonate ions

Transition metal doped TiO2: physical properties and photocatalytic behaviour

Two probe photocatalytic reactions, i.e. ethanoic acid and 4-nitrophenol photooxidation, were carried out in different experimental conditions by using suspensions of transition metal (Co, Cr, Cu, Fe, Mo, V and W) doped polycrystalline TiO2 powders in aqueous systems. A beneficial influence of the presence of metal species was observed only with the samples containing copper and tungsten. In particular, the TiO2/Cu powders showed to be more photoactive of bare TiO2 for the ethanoic acid oxidation while the TiO2/W samples were more efficient for 4-nitrophenol degradation. A tentative interpretation is provided on the basis of the values of the points of zero charge of the powders and of the rate constants of recombination of photogenerated electrons and holes, determined by femtosecond pump-probe diffuse reflectance spectroscopy (PP-DRS)