1,721,172 research outputs found
Carbon supports for electrodeposited Pt-Ru catalysts
No full textThe effect of the type of carbon support on the catalytic activity of Pt-Ru/C catalysts for methanol oxidation in direct methanol fuel cells (DMFC) was investigated. The morphological and structural properties of high surface area (>200 m2g-1) carbon powders and such electrochemical parameters of carbon-Nafion composites as accessible surface area and electric resistance are related to the structure, morphology and catalytic activity of Pt-Ru catalysts electrochemically prepared on carbon-Nafion supports. Key data are reported, discussed and compared to those obtained with a commercial Pt-Ru/C catalyst
Lithiation/delithiation performance of Cu6Sn5 with carbon paper as current collectors
No full textLithiation/delithiation of Cu6Sn5 both electrochemically and mechanochemically prepared on a carbon paper (CP) current collector was investigated by repeated galvanostatic cycles with time-limited charges to insert different amounts of lithium per Sn atom (Li/Sn) into the alloy. The results demonstrated that, unlike Cu6Sn5 electrodeposited on Cu foil, both electrochemical and mechanochemical Cu6Sn5 on CP can undergo hundreds of lithiathion/delithiation cycles with Li/Sn > 2 at high current density (0.74 mA cm-2), thereby delivering constant amounts of charge with coulombic efficiency near 100%. The Cu6Sn5/CP electrodes with loading of 6.6 mg cm-2 and charge limited to 2.43 Li/Sn yielded a specific capacity of 330 mAh g-1 and a capacity for geometric area of 2.18 mAh cm-2, which compare well with the values of graphite-based anodes of commercial batteries. The significant improvement on cyclability performance of the Cu6Sn5/CP electrodes is due to the carbon paper current collector’s three-dimensional conductive matrix, which preserves the electric contact over cycling so that alloy cracking becomes less detrimental for the electric contact
Performance of polymer-based supercapacitors
No full textSupercapacitors are now attracting much attention as an electric vehicle power source. The present study focuses on redox supercapacitors with electronically conducting polymers as electrode materials. Performance data of a symmetric supercapacitor based on p-doped poly(pyrrole), of an unsymmetric supercapacitor based on p-doped poly(pyrrole) and poly(3- methylthiophene), and of a symmetric sypercapacitor based on p- and n-doped poly(dithieno[3,4-b:3′,4′-d]thiophene) are here compared
Pseudocapacitive and Ion‐Insertion Materials: A Bridge between Energy Storage, Electronics and Neuromorphic Computing
Full text linkThere is considerable interest in new solid-state materials for many applications, from energy storage to electronics and neuromorphic computing. This concept paper highlights how pseudocapacitive and ion-insertion materials, for their inherent capability of storing charge and modulate electron conduction, represent a bridge between energy storage, electronics and neuromorphic computing and enable the design of new device architectures
Carbon paper as three dimensional conducting substrate for tin anodes in lithium-ion batteries
No full textTin on a carbon paper (CP) was investigated by repeated galvanostatic cycles with time-limited charges to insert different amounts of lithium per Sn atom, and tin electrodeposited on copper was also investigated for comparison of the cyclic stability. The results demonstrated that, unlike Sn electrodeposited on Cu foil, Sn on CP can undergo several ten of lithiathion/delithiation cycles with Li/Sn atomic ratio  2 at high current density (0.70 mA cm-2), thus confirming that carbon paper is a good current collector-substrate which is able even to improve the cycling performance of tin by preserving the electric contact over cycling, in spite of the great volume changes during the lithium insertion/removal processes in tin
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
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
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