1,720,973 research outputs found
Optimising CNF-supported cobalt catalysts for enhanced oxygen evolution reaction activity through plasma modification
No full textTransition metal–carbon composite materials constitute a very robust class of materials that can meet the alkaline OER demands. Cobalt spinel exhibits good OER activity and stability among the transition metal compounds. On the other hand, carbon nanofibers (CNF), characterised by high oxidation resistance, surface area and electrical conductivity, appear to be a natural choice for a metal oxide active phase support. In this study, we used a low-temperature plasma for a facile surface functionalisation with oxygen groups to boost the OER activity of the cobalt phase. The cobalt phase’s dispersion was the most critical factor in obtaining the best OER activity of the CNF-supported cobalt electrocatalysts. The deposition of the cobalt phase on the CNF improves the stability of the catalytic system compared to the unsupported cobalt spinel by protecting the electrode and polymer film from extensive oxidative degradation
Mesoporous cobalt oxide for oxygen evolution reaction under alkaline conditions: a comparative study of three synthesis methods
No full textIn this work three different synthesis routes were studied for producing mesoporous cobalt oxide. The Silica Template (ST), the Solution Combustion Synthesis (SCS), and the Co-Precipitation (CP) methods are compared. The catalysts synthesized were tested under alkaline conditions by a three-electrode setup and a gas diffusion electrode, in order to evaluated their electrochemical evolution of oxygen from water. Cobalt oxide produced by ST method shows the highest activity through OER and consequently the lowest overpotential. In fact, the onset potential starts at 1.57 V (vs. RHE) with a maximum current density of 19 mA cm-2 at 1.84
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
Structural promotion of cryptomelane (KMn8O16) and its reactivity in oxygen evolution reaction
No full text
The Role of Open Cell Foams Supports on the Kinetics of PdO/Co3 O4 for the Wet and Dry Lean Methane Combustion
Full text linkIn this study, a kinetic analysis under differential conditions was conducted on three different open cell foams (OCFs) materials—FCA(FeCrAl)- OCF, SiC(silicon carbide)- OCF, and Alu(alumina)-OCF—w ashcoated with a PdO/Co3O4 catalyst for lean methane combustion in both dry and wet environments (10 vol% H2O). A comprehensive set of physicochemical characterizations, including CO chemisorption, FESEM, XRD, Raman spectroscopy, XPS, XRF, TPR, TPO, and TPD, was performed on the supported catalysts. All structures demonstrated comparable catalytic activity and excellent water stability over time. The activation energy was consistent across all catalytic systems, with values of approximately 117 kJ mol−1 in dry conditions and 129 kJ mol−1 in wet conditions. While all catalysts exhibited first-order kinetics with respect to methane, variations in water order were observed: –0.9 for Alu-OCF, –0.7 for FCA-OCF and SiC-OCF. Additionally, the preexponential factors in wet conditions followed the order Alu- OCF > SiC- OCF > FCA- OCF, which corresponded with the order of turnover frequencies. Validation of the kinetic modeling results was performed against the experimental data. The hydrophobicity of the supports appeared to play a role in water inhibition, with SiC-OCF, the most hydrophobic of the materials tested, demonstrating superior catalytic activity
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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