1,721,055 research outputs found
Enhanced Photocatalytic Hydrogen Production from Glucose Aqueous Solution Using Nickel Supported on LaFeO3
No full textNowadays one of the topics of greatest interest to the scientific community is the search for new eco-friendly technologies that allow the production of energy. In particular, one of the main players in this area is hydrogen. Several innovative processes are proposed in the literature for the production of hydrogen. One of these is the heterogeneous photocatalysis. Furthermore, it is also interesting to evaluate the source from which hydrogen is obtained. An interesting solution is glucose, one of the most familiar biomass, which can be used to produce hydrogen from a photocatalytic process. For this reason, in this work we propose the use of Ni as active phase supported on LaFeO3 photocatalyst for the renewable H2 production from glucose aqueous solution. Perovskite photocatalysts are quite encouraging materials for H2 production from aqueous solution owing to their stability in water. Low-cost nickel can be used to improve the performance of perovskites, modifing their surface and thus avoiding the use of expensive noble metal based cocatalysts. Specifically, the LaFeO3 catalyst was prepared by solution combustion synthesis using citric acid as organic fuel. A specific amount of Ni was deposited on LaFeO3 surface by chemical reduction method, using sodium borohydride (NaBH4) as a reducing agent. The prepared samples were characterized by different techniques, such as XRD and UV-Vis. The photocatalytic tests were carried out in a pyrex cylindrical reactor equipped with a N2 distributor device and irradiated by four UV lamps (emitting at 365 nm) positioned at the same distance from the external surface of the reactor (about 30 mm). The tests were realized with a solution volume equal to 80 ml, an initial concentration of glucose equal to 5550 umol L-1 and a catalyst dosage equal to 1.5 g L-1. The experimental results evidenced that the presence of Ni on LaFeO3 surface enhanced the H2 production and in particular the highest hydrogen production (about 2242 umol L-1 after 4 h of irradiation time) was obtained with Ni/LaFeO3, whereas the raw LaFeO3 was able to produce a lower H2 amount (about 1394 umol L-1 after the same irradiation time)
Ag-Decorated TiO2 in a fluidized bed photoreactor: A high-efficiency system for the direct photocatalytic epoxidation of propylene to propylene oxide
No full textThe selective photocatalytic epoxidation of propylene represents a sustainable alternative to traditional industrial processes, offering milder operating conditions and reduced environmental impact. In this study, TiO2-based photocatalysts decorated with noble metals (Pt, Pd, Au, and Ag) were synthesised via photodeposition and evaluated in a UV-A-irradiated fluidized bed photoreactor. Physicochemical characterisation confirmed the predominance of the anatase phase, successful noble metal incorporation, and enhanced optical properties. Among the tested materials, Ag/TiO2 demonstrated the best performance, achieving the highest propylene conversion (43.5 %), the highest PO yield (20.5 %), and the lowest specific energy consumption (0.02 kWh molC3H6-1). Optimisation of operating conditions revealed a strong dependence of activity and selectivity on temperature, light intensity, and reactant concentration. Mechanistic analysis highlighted the role of Schottky barrier formation and reactive oxygen species generation in determining photocatalytic performance. Compared to previously studied systems Ag/TiO2 exhibited superior conversion and energy efficiency, confirming its potential for scalable, sustainable PO production. This work establishes a comprehensive framework for the development of efficient gas-phase photocatalytic processes aligned with green chemistry principles
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Performances of V2O5 based catalysts, obtained by grafting vanadyl triisopropoxide on TiO2-SiO2 in SCR
No full textThe influence of sulphate on the catalytic properties of V2O5-TiO2 and WO3-TiO2 in the reduction of nitric oxide with ammonia
No full textVisible light-driven photocatalytic performance of ZnO coupled with up-conversion phosphors for the removal of methylene blue
No full textIn this work it was investigated the photocatalytic activity of ZnO coupled with inorganic “up-conversion” phosphors for the treatment of aqueous solutions polluted with methylene blue (MB), in the presence of visible light irradiation. Specifically, the successfully prepared “up-conversion” phosphors nanoparticles emit, when excited with visible light, UV light with main emission at 365 nm. The photocatalytic tests were carried out in a cylindrical pyrex photoreactor equipped with a magnetic stirrer to ensure the continuous mixing of the physical mixtures of “up-conversion” phosphors and commercial ZnO nanoparticles in the solution and irradiated by visible light instead of UV light normally required to excite ZNO. Experimental results were analysed by evaluating the MB decolourization through spectrophotometric method and the total organic carbon (TOC) through high temperature combustion method. In particular, it was found that the photocatalytic performances obtained using ZnO nanoparticles coupled with “up-conversion” phosphors are strongly increased compared to the use of ZnO alone. These results confirmed the enhancement of photocatalytic performances induced by UV photons emitted by “up-conversion” phosphors nanoparticles, able to activate ZnO, demonstrating how their use in photocatalytic systems can be an alternative to the traditional UV lamps, thus preserving human health, environmental and, at the same time, allows to save the energy in process management
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