1,720,981 research outputs found
Performance of the RuO2 Catalyst Layer with Nonuniform Ionomer Distribution for Water Electrolysis
No full textProton exchange membrane water electrolysis (PEMWE) stands out as a promising technology for producing highly pure hydrogen at a high voltage efficiency and with minimal impact on the environment. The manufacturing method of the catalyst layer still needs more fine-tuning to improve the performance and lifetime of PEMWE even with notable progress in materials development. In this work, we showcase the sensitivity of the polarization at the RuO2 anode to the spatial distribution of the ionomer within the catalyst layer over short- and long-term operation. A series of anode electrodes with different formulations are systematically prepared and characterized to quantify the interplay between the components' spatial distribution and the polarization behavior during water electrolysis. The results point to the more efficient utilization of the catalyst particles in a graded electrode, as substantiated by Tafel and voltammetry analysis. Electrochemical impedance spectroscopy identifies electronic and ionic charge transport as the dominant loss phenomena in the bulk and at interfaces, respectively. Our results suggest that the aging rate at the catalyst layer is influenced by the ionomer content and is higher close to the membrane. By exploring the formulation parameters of the graded catalyst layer, this work seeks to contribute to the development of more efficient PEM electrolysis systems, paving the way for a sustainable hydrogen economy.The authors are grateful to the BOF at Hasselt University for the financial support of this work in the context of the CleanH2 project
Aggregation-Induced Modulation of the Optoelectronic Properties of Carbon Dots and Removal of Cd2+ Ions with Sustainable Use in Photocurrent Generation
No full textHerein, we report the room-temperature fabrication of carbon dots (C-dots) using UV light irradiation within 15 min. The formation pathway has been investigated by time-dependent mass spectroscopic and transmission electron microscopic (TEM) studies. The inherent insolubility of carbon dots in organic solvents has been overcome by employing the phase-transfer strategy, and the C-dots have been found to remain in aggregated state in organic solvents. Interestingly, aggregation leads to the generation of a considerable amount of current conductivity in carbon dots, as is evident by current-voltage (I-V) measurements. This is not attainable by carbon dots in aqueous solution. However, the aggregates of C-dots do not show any photocurrent response. The phase transfer of C-dots has also been utilized to remove the toxic Cd2+ions from contaminated water by dragging them into the organic solvents with carbon dots. The C-dots-metal hybrid obtained by the removal of Cd2+with carbon dots in organic medium shows a very good photoresponsive nature with significant photogain. This suggests proper utilization of the removed (from polluted water) cadmium ions in a sustainable manner for photocurrent generation
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
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
Hydrothermal synthesis of Mo and Fe sulfides for the HER in PEM water electrolysis
No full textHydrothermal synthesis of Mo and Fe sulfides for the HER in PEM water electrolysis
Naomi Billieta,b, Dries De Slooverea,b, Mohammadhosein Safarib,c, Marlies K. Van Baela,b, An Hardya,b
aUHasselt, Institute for Materials Research (IMO-Imomec) and Imec division Imomec, DESINe, Agoralaan, building D, 3590 Diepenbeek, Belgium.
bEnergyVille, Thor Park 8320, 3600 Genk, Belgium.
cUHasselt, Institute for Materials Research (IMO-Imomec) and Imec division Imomec, Electrochemical Engineering (EE), Wetenschapspark 1, 3590 Diepenbeek, Belgium.
Hydrogen gas (H2) has the potential to be a sustainable energy carrier, as it has a high energy density, does not release CO2, and is a feedstock chemical in various industries. Unfortunately, H2 is mainly produced from fossil fuels by steam methane reforming, naphtha reforming, and coal gasification.1,2 A promising alternative is water splitting through electrolysis, which produces H2 and O2 via the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. As a major advantage, this method does not release CO2 or other volatile by-products.3 Commercial water electrolysis methods are alkaline electrolysis and PEM (proton exchange membrane) electrolysis. The advantages of PEM electrolysis are higher energy efficiency, quick response, and scalability.4 However, the used catalyst for the HER in PEM electrolysis is Pt, an expensive and low-abundance material. Therefore, this research aims to find earth-abundant alternatives to catalyze the HER. Molybdenum disulfide (MoS2) is a widely known alternative catalyst due to its high catalytic activity and high stability.5 Other sulfides such as Fe sulfides, were also found to be active as HER catalysts.6 This implies that a whole range of mixed metal sulfides may have a catalytic performance and stability that outperforms the more established materials.
In this study, Mo and Fe sulfides were synthesized via similar hydrothermal methods. The variation of parameters such as temperature and reaction time, allowed the synthesis of particles with a wide range of morphologies. However, attempts to synthesize mixed metal (Mo,Fe) sulfides via similar routes resulted in the formation of distinct MoS2 and Fe sulfide phases. Instead, the synthesis of (Mo,Fe) sulfides required the preparation of an amorphous Keplerate-type phase as a synthetic intermediate. The synthesized materials were characterized using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) to investigate their morphology and crystal structure. The catalytic performances of the synthesized materials were compared with linear sweep voltammetry (LSV) using a three-electrode cell. Whatever the material and morphology, the quality of the electrocatalytic films was determining for its catalytic activity.
Our solution-based synthesis strategies allow the synthesis of (mixed) metal sulfides in a range of different particle morphologies. Therefore, these strategies provide an ideal way to tune the electrocatalytic behavior of these materials as HER catalyst.
1. Agyekum, E. B., et al. (2022). In Membranes (Vol. 12, Issue 2). MDPI. https://doi.org/10.3390/membranes12020173
2. Das, A., et al. (2022). In Sustainability (Switzerland) (Vol. 14, Issue 18). MDPI. https://doi.org/10.3390/su141811206
3. Shiva Kumar, S., et al. (2019). Materials Science for Energy Technologies, March. https://doi.org/10.1016/j.mset.2019.03.002
4. Guo, Y. et al. (2019). IOP Conference series: Earth and Environmental Science. 371, p4. http://dx.doi.org/10.1088/1755-1315/371/4/042022
5. Li, R., et al. (2022). Chemical Communications, 58(14), 2259–2278. https://doi.org/10.1039/d1cc04004a
6. Heift, D. (2019). In Inorganics (Vol. 7, Issue 6). https://doi.org/10.3390/INORGANICS706007
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