1,720,959 research outputs found
Catalizzatori nanostrutturati per la conversione sostenibile della CO2
No full textNegli ultimi anni, diverse strategie sono state studiate al fine di mitigare l'impatto delle emissioni di CO2 sull'atmosfera. In particolare, la riduzione di CO2 risulta essere un promettente approccio per il riuso di questo gas e la sua diretta conversione in combustibili o prodotti chimici. Nonostante i grandi miglioramenti degli ultimi decenni, questi metodi presentano ancora una differenza tra l’utilizzo ai fini di ricerca e l’applicabilità a livello industriale a causa degli alti costi dell'intero processo e della durata dei catalizzatori. I catalizzatori svolgono un ruolo fondamentale in questa tipologia di applicazioni e le loro caratteristiche, come l'attività catalitica, la selettività e la stabilità nel tempo, sono aspetti cruciali per permettere l’utilizzo di questi processi a livello industriale. La nanostrutturazione è un fattore chiave per ottimizzare la morfologia del catalizzatore su scala nanometrica e migliorarne le prestazioni complessive.
Il lavoro presentato verte sullo sviluppo e la caratterizzazione di catalizzatori nanostrutturati per la riduzione di CO2. L'uso di tecniche sintetiche avanzate e caratterizzazioni morfologiche, tessiturali e (elettro)chimiche, ha permesso di ottimizzare vari catalizzatori per diverse applicazioni. In particolare, catalizzatori a base di Cu sono stati studiati per il processo di riduzione elettrochimica della CO2 (eCO2RR). In primo luogo, nanoparticelle di Cu2O dalla forma specifica sono state sintetizzate e studiate come catalizzatori nel processo di eCO2RR, mostrando un diverso comportamento catalitico e una bassa selettività verso un particolare prodotto della riduzione. Inoltre, la caratterizzazione XAS in operando ha confermato una rapida riduzione del materiale a Cu metallico. Per superare questi limiti, lo studio esplora la formazione di eterostrutture e l'utilizzo di materiali 2D come g-C3N4, RGO e MoS2, mostrando una migliore selettività catalitica e produttività nei confronti di determinati prodotti. Inoltre, la sintesi di leghe di CuSn bimetalliche attraverso un metodo facile e scalabile come il cosiddetto “Urea Glass Route” può aprire nuove prospettive per l’utilizzo di questo processo a livello industriale.
Nanotubi di TiN decorati con nanoparticelle metalliche sono infine stati utilizzati come catalizzatori per la riduzione fototermica di CO2.
Ulteriori considerazioni relative all'ottimizzazione e all'impatto ambientale sono fondamentali per consentire processi di riduzione di CO2 su larga scala. Il continuo sviluppo in queste aree è essenziale per colmare il divario tra i progressi nella ricerca e l'implementazione su scala industriale delle tecnologie di riciclaggio della CO2.In the recent years, different strategies have been studied to mitigate the impact of CO2 emissions on the global environment. In particular, CO2 reduction has emerged as a promising approach for recycling this gas and the direct conversion to fuels or chemicals. Despite great improvements in the last decades, the recycling of CO2 still suffers a mismatch between the lab and the industrial scales due to the high costs of the entire process and the lifetime of the catalysts. Catalysts play a pivotal role in CO2 reduction applications, and their characteristics, such as catalytic activity, selectivity, and long-term stability, are crucial for enabling the feasibility of this process at an industrial scale. Nanostructuration has been identified as a key factor in tailoring the morphology at the nanoscale and enhancing the overall performance of catalyst materials. The presented work focuses on the development and characterization of nanostructured catalysts for CO2 reduction. The use of advanced synthetic techniques as well as morphological, textural and (electro)chemical characterizations allowed to optimize various catalysts for different applications at the forefront of research. Cu-based catalysts were explored toward the eCO2RR. Firstly, well-defined nanoparticles of Cu2O were synthetized and widely characterized toward eCO2RR, revealing different catalytic behavior and a low selectivity toward a particular product. Moreover, operando XAS characterization confirmed a rapid reduction to metal Cu. To overcome these limitations, the study explores the formation of heterostructures and the utilization of 2D materials like g-C3N4, RGO and MoS2, leading to an improved catalytic selectivity and productivity. On the other hand, the preparation of bimetallic CuSn alloys via an easy and scalable urea glass route can open new perspectives for the affordability of this process at an industrial-scale level. Another approach to exploit nanostructuration for the reduction of CO2 investigated the employing of TiN nanotubes decorated with metal nanoparticles as catalyst for gas-phase photothermal reduction of CO2. Further considerations regarding optimization and environmental impact are fundamental to enable large-scale CO2 reduction processes. Continued research and development in these areas are essential to bridge the gap between laboratory-scale advancements and industrial-scale implementation of CO2 recycling technologies
Well-defined Cu2O photocatalysts for solar fuels and chemicals
No full textThe shape-controlled synthesis of cuprous oxide (Cu2O) photocatalysts with both low or high index crystal planes has received increasing attention due to their unique facet-dependent properties. Since they are cheap and earth abundant, these well-defined Cu2O nanostructures are extensively used for different photocatalytic reactions, also because of their strong visible light absorption capability. However, further development will still be needed to enhance the efficiency and photostability of Cu2O to expand its industrial application. We start this review by summarizing the synthetic advancement in the facet engineering of Cu2O and other associated hybrid Cu2O-based heterostructures with a special emphasis put on their growth mechanism. We then discuss different facet-dependent properties, which are relevant to photocatalysis. In the subsequent section, we present a critical discussion on the photocatalytic performance of faceted Cu2O nanostructures during organic synthesis, hydrogen production, and carbon dioxide photoreduction. The relation between photocatalytic efficiency and product selectivity with exposed crystal facets or with different compositions of hybrid nanostructures is also discussed. Finally, important strategies are proposed to overcome the photostability issue, while outlining the course of future development to further boost the technological readiness of well-defined Cu2O-based photocatalysts
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
CO2 Electroreduction by Engineering the Cu2O/RGO Interphase
Full text linkIn the present investigation, Cu2O-based composites were successfully prepared through a multistep method where cubic Cu2O nanoparticles (CU Cu2O) have been grown on Reduced Graphene Oxide (RGO) nanosheets. The structural and morphological properties of the materials have been studied through a comprehensive characterization, confirming the coexistence of crystalline Cu2O and RGO. Microscopical imaging revealed the intimate contact between the two materials, affecting the size and the distribution of Cu2O nanoparticles on the support. The features of the improved morphology strongly affected the electrochemical behavior of the composites, increasing the activity and the faradaic efficiencies towards the electrochemical CO2 reduction reaction process. CU Cu2O/RGO 2:1 composite displayed selective CO formation over H2, with higher currents compared to pristine Cu2O (−0.34 mA/cm2 for Cu2O and −0.64 mA/cm2 for CU Cu2O/RGO 2:1 at the voltage of −0.8 vs. RHE and in a CO2 atmosphere) and a faradaic efficiency of 50% at −0.9 V vs. RHE. This composition exhibited significantly higher CO production compared to the pristine materials, indicating a favorable *CO intermediate pathway even at lower voltages. The systematic investigation on the effects of nanostructuration on composition, morphology and catalytic behavior is a valuable solution for the formation of effective interphases for the promotion of catalytic properties providing crucial insights for future catalysts design and applications
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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