When sulfur and silicon are incorporated in monolayer 2H-NbSe the superconducting transition temperature, T, has been found to vary non-monotonically. This was assumed to be a manifestation of fractal superconductivity. Using first-principles calculations, we show that the nonmonotonic dependence of T is insufficient evidence for multifractality. A unifying aspect in our study are selenium vacancies in NbSe, which are magnetic pair-breaking defects that we propose can be present in considerable concentrations in as-grown NbSe. We show that sulfur and silicon can occupy the selenium sites and reduce the pair-breaking effect. Furthermore, when sulfur is incorporated in NbSe, the density of states at the Fermi level and the proximity to magnetism in the alloy are both reduced compared to the parent compound. Based on our results, we propose an alternative explanation of the non-monotonic change in T which does not require the conjecture of multifractality.
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http://dx.doi.org/10.1038/s41467-022-29213-8 | DOI Listing |
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December 2024
Institute of Photoelectronic Thin Film Devices and Technology, Renewable Energy Conversion and Storage Center, State Key Laboratory of Photovoltaic Materials and Cells, Nankai University, Tianjin, 300350, P. R. China.
Photovoltaic-driven electrochemical (PV-EC) carbon dioxide reduction (COR) coupled with sulfide oxidation (SOR) can efficiently convert the solar energy into chemical energy, expanding its applications. However, developing low-cost electrocatalysts that exhibit high selectivity and efficiency for both COR and SOR remains a challenge. Herein, a bifunctional copper selenide catalyst is developed with copper vacancies (v-CuSe) for the COR-SOR.
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December 2024
Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK.
Alongside the Chicxulub meteorite impact, Deccan volcanism is considered a primary trigger for the Cretaceous-Paleogene (K-Pg) mass extinction. Models suggest that volcanic outgassing of carbon and sulfur-potent environmental stressors-drove global temperature change, but the relative timing, duration, and magnitude of such change remains uncertain. Here, we use the organic paleothermometer MBT' and the carbon-isotope composition of two K-Pg-spanning lignites from the western Unites States, to test models of volcanogenic air temperature change in the ~100 kyr before the mass extinction.
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December 2024
Department of Chemistry, 316 Physical Science, Oklahoma State University, Stillwater, OK 74078, USA.
One method for the colorimetric detection of hydrogen peroxide vapor is based on a titanium-hydrogen peroxide complex. A color changing material based on a titania hydroxypropyl cellulose thin film was initially developed. However, as this material dries, the sensitivity of the material is significantly reduced.
View Article and Find Full Text PDFHeliyon
November 2024
North South University, Dhaka, 1229, Bangladesh.
Thin-film solar cells are a substitute for more common crystalline silicon solar cells, which consist of thin semiconductor layers. Thin-film materials comprise direct bandgap and can absorb sunlight more efficiently than silicon. In this article, a double-absorber-based thin-film solar cell comprising CZTS/CZTSSe is designed and optimized through numerical simulation.
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December 2024
Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan.
Reactions of cyclic thioureas (1,3,4,5-tetramethylimidazol-2-thione and 1,3-dimethylimidazolidin-2-thione) and ureas (1,3,4,5-tetramethylimidazol-2-one and 1,3-dimethylimidazolidin-2-one) with an isolable dialkylsilylene were examined. In these reactions, cyclic thioureas served as sulfur and NHC (N-heterocyclic carbene) sources, and the corresponding silanethione and NHC-derived products formed via silanethione-NHC complexes. Reactions of cyclic ureas with the silylene afforded a new NHC and an isolable azomethine ylide.
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