1,720,966 research outputs found
Reproducibility and alternative electrochemical methods for testing ORR/OER electrocatalysts
No full textScreening potential new electrocatalyst materials for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is a crucial component for the advancement of energy storage and conversion devices. Drop casting catalyst inks onto a rotating disc/rotating ring disc electrode (RDE/RRDE) surface is a widely used screening method due to its speed and simplicity, however, it is highly sensitive to electrode preparation and measurement conditions which limits reproducibility and comparability across studies. The first section of this thesis systematically investigates the impact of three modifications to the drop casting procedure: the use of a heat lamp during drying, electrode rotation during drying, and the inclusion of IPA in the ink. Electrochemical performance and catalyst distribution were analysed with RRDE measurements and large area energy dispersive x-ray spectroscopy (EDS) mapping. The electrodes that were dried at rotation or with a heat lamp exhibited lower OER currents and smaller confidence deviations. EDS analysis showed rougher surfaces for IPA containing inks and the formation of concentrated rings of catalyst material on some rotated electrodes, with no electrode achieving uniform catalyst distribution. Contact angle measurements also showed lower angles for the electrodes dried without a heat lamp, rotation, or IPA.The second section introduces sampled current voltammetry (SCV) as a potential alternative catalyst screening technique due to the correlation between RDE/RRDE rotation rate and SCV sampling time. SCV applies a series of steps from a rest potential to a target potential and back to the rest potential again. Current transients are obtained at each target potential step which are then sampled at a specific time, the currents obtained at each target potential for a specific sampling time are then used to construct a sampled current voltammogram. A conditioning procedure is carried out between each target potential step to reduce the influence of electrode history compared to conventional potential sweeping techniques, this was adjusted to control the surface oxide coverage on platinum disc electrodes. Variations to the conditioning procedure upper potential limit (EUP) and rest potential (EREST) showed changes in SCV onset potential and current magnitude, linked to oxide coverage, and anion adsorption. These findings demonstrate SCV as a highly sensitive technique for studying electrode surface processes.The final section of this thesis investigates SCV on higher surface electrodes, including platinum black and electrodeposited transition metal oxides (TMOs). The magnitude of the SCV currents observed for the platinum black electrodes were all much higher than those observed in the rotating disc electrode voltammograms, consistent with utilisation of the full electrode surface area, compared to the geometric surface area considered in RDE. The next part of this chapter focused on electrodeposited TMOs on RDEs and stainless steel electrodes. Electrodes dried at 25°C showed better OER activity, whereas the 500°C dried depositions showed better ORR activity, all depositions showed small errors indicating high reproducibility. Comparison between RDE and SCV testing is complicated for larger surface area electrodes due to the differing surface sensitivities between the two techniques
Dataset supporting thesis titled: "Reproducibility and Alternative Electrochemical Methods for Testing ORR/OER Electrocatalysts"
No full textDataset associated with PhD thesis titled: "Reproducibility and Alternative Electrochemical Methods for Testing ORR/OER Electrocatalysts"</span
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
Oxygen-vacancy rich Co<sub>3</sub>O<sub>4</sub>/CeO<sub>2</sub> interface for enhanced oxygen reduction and evolution reactions
No full textOxygen reduction and evolution reactions (ORR and OER, respectively) are the two most extensively studied reactions in electrochemistry. Herein, we report the synthesis of Co3O4/CeO2/GNP (GNP = graphene nanoplatelet) electrocatalyst for ORR and OER that exhibits an early onset potential (0.85 V) and half-wave potential (E1/2) of 0.69 V for ORR. The reported catalyst is highly durable with 87.6% retention of its initial current after a 6 h chronoamperometry test compared to 72.5% by Pt/C. It exhibits a negligible shift of E1/2 after 10,000 potential cycles for ORR. Heterogeneous oxide/oxide interfaces, oxygen vacancies and semicrystalline nature are inferenced to play a dominant role in altering the collective catalytic efficiency of Co3O4/CeO2/GNP. High concentration of oxygen vacancy defects (68%) in Co3O4/CeO2/GNP is presumed to play a dominant role here. The catalyst is bifunctional for ORR and OER with a bifunctionality index of 0.98 V and operates at an overpotential of ƞ10 = 440 mV for OER. Ex situ X-ray absorption studies indicate an increased average oxidation state of Co by 15% in Co3O4/CeO2/GNP compared to Co3O4/GNP, aiding in preserving its inherent catalytic nature of spinel CO3O4
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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