1,720,960 research outputs found
Biomimetic 2D-Ni(Co,Fe)P/1D-WOx nanocoral reef electrocatalysts for efficient water splitting
No full textThe design of efficient nanostructured electrocatalysts is highly desirable for promoting the hydrogen/oxygen evolution reactions (HER/OER), which are key processes of ecofriendly H-2 production in water splitting systems. In this study, we present novel biomimetic hierarchical nanocoral reef materials as efficient and durable electrocatalysts for alkaline water splitting. Our nanocoral reef catalyst has a unique structure consisting of Ni(Co,Fe)P nanosheet (NS) algae and WOx nanowire (NW) corals. The WOx NW corals effectively transport charges (e(-)/h(+)) to the Ni(Co,Fe)P NS algae through a 1D directional structure. The ultrathin 2D Ni(Co,Fe)P NS algae grown on the WOx NW corals provide an abundance of active sites for splitting water molecules into H-2 and O-2. As a result, our hierarchical 2D-NS/1D-NW-structured NiCoP-WOx (HER) and NiFeP-WOx (OER) catalysts demonstrate excellent activities, requiring low overpotentials of 49 and 270 mV, respectively, to generate a current density of 10 mA cm(-2). Additionally, they exhibit high electrochemical stability for over 60 h in 1 M KOH. In addition, the overall water splitting (OWS) system, NiCoP-WOx(HER)||NiFeP-WOx(OER) requires a cell voltage of 1.51 V to generate a current density of 10 mA cm(-2). This value is very low compared to other reported transition metal phosphides. The biomimetic engineering presented in the current study provides not only efficient electrocatalysts but also a promising, useful strategy to develop functional 1D/2D hierarchical materials for advanced energy applications.11Nsciescopu
Suppressing Anion Repulsion for Enhancing Li-Mediated Nitrogen Reduction
No full textElectrochemical lithium-mediated nitrogen reduction (Li-NRR) presents a sustainable alternative to Haber-Bosch for ammonia synthesis. Efficiency and stability are critically governed by the solid electrolyte interphase (SEI), which regulates reactant transport and suppresses side reactions. While anion-derived SEI formed under anion-rich solvation is beneficial, conventional electric double layer (EDL) repel anion at the cathode, limiting favorable SEI formation. Therefore, this study introduces cationic ionomer additives that form a positively charged ionic interfacial layer, mitigating anion repulsion and reducing interfacial solvent accumulation. An imidazolium (C3H4N2)-functionalized cation ionomer enables the formation of a tailored EDL, achieving a Faradaic efficiency and ammonia yield of 92 +/- 3% and 58 +/- 4 nmol s-1 cm-2, markedly surpassing the conventional EDL (63 +/- 7%, 28 +/- 9 nmol s-1 cm-2). A significant decrease in anion repulsion was confirmed via computational and in situ spectroscopic analyses. The demonstrated applicability across various lithium salts clearly reveals the overall effectiveness of this cationic ionomer-based EDL engineering in Li-NRR.
2D-structured V-doped Ni(Co,Fe) phosphides with enhanced charge transfer and reactive sites for highly efficient overall water splitting electrocatalysts
No full text2-D Ni alloy phosphide catalysts are of great interest due to their strong bond strength to reaction intermediates and numerous active sites for alkaline overall water splitting (OWS) reactions. However, the limitations of hydrogen evolution reaction (HER) activity and electrical conductivity significantly lower the OWS activity compared to noble metal catalysts. To overcome this problem, V-doping of 2D Ni(Co,Fe) phosphide was performed to increase the electrical conductivity and catalytic activity by tuning the electron density of the active sites. The synthesized NiCoVP had a low Tafel slope of 30 mV dec(-1) and a reduced overpotential of 42 mV compared to NiCoP (75 mV), which has high stability as an alkaline HER catalyst, yielding 10 mA cm(-2). The charge transfer resistance also decreased from 8.8 omega (NiCoP) to 7.1 omega (NiCoVP). As an alkaline oxygen evolution reaction (OER) catalyst, NiFeVP showed a low overpotential of 234 mV to generate 10 mA cm(-2) compared to NiFeP (249 mV) with a Tafel slope of 34.4 mV dec(-1). V doping reduced the charge transfer resistance from 3.6 omega (NiFeP) to 1.2 omega (NiFeVP). The OWS system combining NiCoVP-NiFeVP required 1.50 V for 10 mA cm(-2), which is the lowest among the transition metal-based phosphide catalysts reported so far. This marked improvement in alkaline OWS activity through V doping was also proven by the density functional theory (DFT) calculation results of high affinity to *OH, which enhances water dissociation for the HER and strong metal-O covalence bonds for the OER.11Nsciescopu
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
An Overview of Emerging Catalytic Materials for Electrochemical Green Ammonia Synthesis and Process
No full text11Nsciescopu
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
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