1,721,066 research outputs found
Solar spectrum photocatalytic conversion of CO2 to CH4 utilizing TiO2 nanotube arrays embedded with graphene quantum dots
No full textTiO2 nanotube arrays (TNT) offer an exciting prospect as a photocatalytic material architecture due to the combined properties of high surface area, 1-D vectorial charge transfer, and reduced photogenerated charge recombination. However the TiO2 band gap (≈3.2eV) limits light absorption to the UV region, which comprises but a small fraction of the solar spectrum energy. Graphene is known to effectively absorb visible light, and due to its high conductivity promote efficient charge transfer. Herein, we present a novel photocatalyst composed of TNTs sensitized with electrodeposited graphene quantum dots (GQDs). GQDs electrodeposition-duration is varied to optimize photocatalytic performance of the resulting nanostructured graphene-TNT (G-TNT) films. Under solar spectrum illumination we find optimal G-TNT samples promote a CO2 to CH4 photocatalytic conversion rate of 1.98ppmcm-2 h-1, with carbon origin confirmed by 13CO2 isotopic test. © 2018 Elsevier Ltd. All rights reserved.1
Photocatalytic conversion of CO2 into hydrocarbon fuels with standard titania Degussa P25 using newly installed experimental setup
No full textPhotoreduction of into hydrocarbon fuels on the surface of photocatalyst is one of the breakthroughs in the field of photocatalysis. At present various approaches have been investigated with the aim of increasing the conversion efficiency. The reactor for photoconversion of plays a vital role in experimental setup. In this work an attempt was made to testify a newly designed the photoreactor for conversion of into useful products. The photoreactor was specifically designed for simple operation bearing features of temperature and pressure control. The reactor has been tested successively with the standard titania, Degussa P25 yielding methane with moderate production rate of 30.8 under UV lamp with 365 nm wavelength. The methane yield obtained is comparable to the values reported in literature. Thus we anticipate that this experimental setup equipped with newly designed photoreactor can yield competitive amounts of fuels from photoredcution via 365 nm UV light illumination on various photocatalysts.1
Recent Advances in Quantum Dots for Photocatalytic CO2 Reduction: A Mini-Review
Full text linkSolar energy–driven carbon dioxide (CO2) reduction to valuable solar fuels/chemicals (e.g., methane, ethanol, and carbon monoxide) using particulate photocatalysts is regarded as one of the promising and effective approaches to deal with energy scarcity and global warming. The growth of nanotechnology plays an eminent role in improving CO2 reduction (CO2R) efficiencies by means of offering opportunities to tailor the morphology of photocatalysts at a nanoscale regime to achieve enhanced surface reactivity, solar light absorption, and charge separation, which are decisive factors for high CO2R efficiency. Notably, quantum dots (QDs), tiny pieces of semiconductors with sizes below 20 nm, offering a myriad of advantages including maximum surface atoms, very short charge migration lengths, size-dependent energy band positions, multiple exciton generation effect, and unique optical properties, have recently become a rising star in the CO2R application. In this review, we briefly summarized the progress so far achieved in QD-assisted CO2 photoreduction, highlighting the advantages of QDs prepared with diverse chemical compositions such as metal oxides, metal chalcogenides, carbon, metal halide perovskites, and MXenes. © Copyright © 2021 Park, Murali, Modigunta, In and In.1
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
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
Surface Modification of Electrocatalyst for Optimal Adsorption of Reactants in Oxygen Evolution Reaction
No full textTechnological development after the industrial revolution has improved the quality of human life, but global energy consumption continues to increase due to population growth and the development of fossil fuels. Therefore, numerous studies have been conducted to develop sustainable long-term and renewable alternative energy sources. The anodic electrode, which is one of the two-electrode system components, is an essential element for effective energy production. In general, precious metal-based electrocatalysts show high OER reactions from the anodic electrode, but it is difficult to scale up due to their low abundance and high cost. To overcome these problems, transition metal-based anodic electrodes, which exhibit advantages with respect to their low cost and high catalytic activities, are in the spotlight nowadays. Among them, stainless steel is a material with a high ratio of transition metal components, i.e., Fe, Ni, and Cr, and has excellent corrosion resistance and low cost. However, stainless steel shows low electrochemical performance due to its slow sluggish kinetics and lack of active sites. In this study, we fabricated surface modified electrodes by two methods: (i) anodization and (ii) hydrogen peroxide (H2O2) immersion treatments. As a result of comparing the two methods, the change of the electrode surface and the electrochemical properties were not confirmed in the H2O2 immersion method. On the other hand, the porous electrode (PE) fabricated through electrochemical anodization shows a low charge transfer resistance (Rct) and high OER activity due to its large surface area compared to the conventional electrode (CE). These results confirm that the synthesis process of H2O2 immersion is an unsuitable method for surface modification. In contrast, the PE fabricated by anodization can increase the OER activity by providing high adsorption of reactants through surface modification
Hybrid CuxO–TiO2 Heterostructured Composites for Photocatalytic CO2 Reduction into Methane Using Solar Irradiation: Sunlight into Fuel
Full text linkPhotocatalytic CO2 conversion to fuel offers an exciting prospect for solar energy storage and transportation thereof. Several photocatalysts have been employed for CO2 photoreduction; the challenge of realizing a low-cost, readily synthesized photocorrosion-stable photocatalytic material that absorbs and successfully utilizes a broad portion of the solar spectrum energy is as yet unmet. Herein, a mesoporous p-type/n-type heterojunction material, CuxO-TiO2 (x = 1, 2), is synthesized via annealing of Cu/Cu2O nanocomposites mixed with a TiO2 precursor (TiCl4). Such an experimental approach in which two materials of diverse bandgaps are coupled provides a simultaneous opportunity for greater light absorption and rapid charge separation because of the intrinsic p-n heterojunction nature of the material. As detailed herein, this heterostructured photocatalyst demonstrates an improved photocatalytic activity. With the CO2 reduction of our optimal sample (augmented light absorption, efficacious charge separation, and mesoporosity) that utilizes no metal cocatalysts, a remarkable methane yield of 221.63 ppm·g-1·h-1 is achieved. © 2016 American Chemical Society.1
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
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