1,721,242 research outputs found
Bulk β-Te to few layered β-tellurenes: indirect to direct band-Gap transitions showing semiconducting property
No full textHerein we report a prediction of a highly kinetic stable layered structure of tellurium (namely, bulk beta-Te), which is similar to these layered bulk materials such as graphite, black phosphorus, and gray arsenic. Bulk beta-Te turns out to be a semiconductor that has a band gap of 0.325 eV (HSE06: 0.605 eV), based on first-principles calculations. Moreover, the single-layer form of the bulk beta-Te, called beta-tellurene, is predicted to have a high stability. When the bulk beta-Te is thinned to one atomic layer, an indirect semiconductor of band gap is changed to 1.265 eV (HSE06: 1.932 eV) with a very high kinetic stability. Interestingly, an increase of the number of the beta-tellurene layers from one to three is accompanied by a shift from an indirect to direct band gap. Furthermore, the effective carrier masses, the optical properties and phonon modes of few-layer beta-tellurenes are characterized. Few-layer beta-tellurenes strongly absorb the ultraviolet and blue-violet visible lights. The dramatic changes in the electronic structure and excellent photo absorptivities are expected to pave the way for high speed ultrathin transistors, as well as optoelectronic devices working in the UV or blue-green visible regions. © Copyright 2017 IOP Publishing Terms & conditions Disclaimer11sciescopu
Highly Enhanced Photoelectrocatalytic Oxidation via Cooperative Effect of Neighboring Two Different Metal Oxides for Water Purification
No full textCopyright © 2020 American Chemical Society.The generation of hydroxyl radicals derived from water molecules plays a pivotal role in attacking organic pollutants for the photoelectrocatalytic (PEC) process. To promote the generation efficiency of hydroxyl radicals, remarkably efficient transportation of the induced carriers and water molecules is desirable. Here, we implemented a remarkably enhanced photoelectrocatalytic oxidation via cooperative effect of neighboring two different metal oxides, Bi2MoO6 and Sb-doped SnO2 nanosheets, for water remediation. To realize the highly efficient transportation of the induced carriers, the hierarchical architecture Bi2MoO6 wrapped Sb-doped SnO2 nanosheets are rationally designed and synthesized. Density functional theory (DFT) calculations demonstrate that water molecules prefer to be adsorbed on the surface of Sb-doped SnO2 nanosheets, producing hydroxyl radicals (•OH) on the surface of Bi2MoO6. The cooperation action between Bi2MoO6 and Sb-doped SnO2 nanosheets for the generation of hydroxyl radicals by water photoelectrolysis is enforced as follows: the Sb-doped SnO2 nanosheet layer can act as the supply station of water and rapidly transfer the water molecules to neighboring Bi2MoO6 to generate hydroxyl radical. This work may enlighten the design and construction of advanced photoanode materials for future scale-up of cost-effective water purification and environmental remediation11Nsciescopu
Tuning a compatible interface with LLZTO integrated on cathode material for improving NCM811/LLZTO solid-state battery
No full text© 2020 Elsevier B.V. Poor interfacial contact and severe polarization of nickel-rich cathode materials are crucial problems that must be solved in the development of nickel-rich cathode/garnet-type electrolyte solid-state batteries. Herein, a binder-like Li3PO4 is introduced via an in-situ calcination process to build a compatible and Li+-conductive self-integrated layer of Li6.4La3Zr1.4Ta0.6O12-Li3PO4 on LiNi0.8Co0.1Mn0.1O2 cathode material, with a newly calculation method for estimating the interface compatibility theoretically. In addition, the routine helps weaken the space charge layer of active material commonly inevitable in the case, as demonstrated by calculation of Density Functional Theory and Atomic force microscopy analysis. With the interface engineering, the in-situ generated Li3PO4 tightly fix Li6.4La3Zr1.4Ta0.6O12 on LiNi0.8Co0.1Mn0.1O2, improving the compatibility between LiNi0.8Co0.1Mn0.1O2 cathode material and the solid electrolyte Li6.4La3Zr1.4Ta0.6O12. As a result, the interface-engineered LiNi0.8Co0.1Mn0.1O2/Li6.4La3Zr1.4Ta0.6O12 solid state battery exhibits an initial discharge capacity of 188.8 mAh g−1 at 0.2C (40 mA g−1). Even at 1C, its retention still remained 91.6% (initial value of 130 mAh g−1) after 100 cycles. The SSBs could also work well under high temperature, delivering high initial discharge capacities of 153.4 mAh g−1 (55 °C) and 149.6 mAh g−1 (80 °C) at 1C, respectively. The work provides an effective strategy to improve NCM811-LP-LLZTO SSBs.11Nsciescopu
Constructing two-dimensional holey graphyne with unusual annulative π-extension
No full textHere, we report two-dimensional, single-crystalline holey graphyne (HGY) synthesized in an interfacial two-solvent system through a Castro-Stephens-type coupling reaction from 1,3,5-tribromo-2,4,6-triethynylbenzene. As a new type of 2D carbon allotrope, HGY is alternately linked between benzene rings and C≡C bonds and is composed of a pattern of six-vertex and highly strained, eight-vertex rings and an equal percentage of sp2 and sp hybridized carbon atoms. By combining experimental and theoretical studies, we systematically investigated the stability of HGY and its vibrational and optical properties. Density functional theory computations predicted that HGY is a p-type semiconductor that embraces a direct bandgap (∼1.1 eV) with a high carrier mobility. Transmission electron microscopic studies revealed that the synthesized HGY sheets are highly crystalline with AB stacking. Its semiconducting character, nonlinear sp bonding, and special π-conjugated structure endow HGY with promising applications in optoelectronic, energy harvesting, gas separation, catalysis, water remediation, sensor, and energy-related fields.11Nsciescopu
Efficient ammonia synthesis via electroreduction of nitrite using single-atom Ru-doped Cu nanowire arrays
No full text© The Royal Society of Chemistry 2022. Here, we report the highly active and selective electrocatalytic reduction of NO2- ions to value-added NH3 over a single-atom Ru-modified Cu nanowire array on three-dimensional copper foam (Ru-Cu NW/CF) under ambient conditions. The obtained Ru-Cu NW/CF catalyst exhibited a maximum faradaic efficiency of 94.1% and an NH3 yield up to 211.73 mg h(-1) cm(-2) (0.732 mmol h(-1) cm(-2)), which was approximately five times higher than that of the Cu NW/CF catalyst.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
Phase-selective active sites on ordered/disordered titanium dioxide enable exceptional photocatalytic ammonia synthesis
No full text© The Royal Society of Chemistry 2021. Photocatalytic N-2 fixation to NH3 via defect creation on TiO2 to activate ultra-stable N N has drawn enormous scientific attention, but poor selectivity and low yield rate are the major bottlenecks. Additionally, whether N-2 preferentially adsorbs on phase-selective defect sites on TiO2 in correlation with appropriate band alignment has yet to be explored. Herein, theoretical predictions reveal that the defect sites on disordered anatase (A(d)) preferentially exhibit higher N-2 adsorption ability with a reduced energy barrier for a potential-determining-step (*N-2 to NNH*) than the disordered rutile (R-d) phase of TiO2. Motivated by theoretical simulations, we synthesize a phase-selective disordered-anatase/orderedrutile TiO2 photocatalyst (Na-A(d)/R-o)by sodium-amine treatment of P25-TiO2 under ambient conditions, which exhibits an efficient NH3 formation rate of 432 mu mol g(-1) h(-1), which is superior to that of any other defect-rich disordered TiO2 under solar illumination with a high apparent quantum efficiency of 13.6% at 340 nm. The multi-synergistic effects including selective N-2 chemisorption on the defect sites of Na-A(d) with enhanced visible-light absorption, suitable band alignment, and rapid interfacial charge separation with R-o enable substantially enhanced N-2 fixation.11Nsciescopu
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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