We utilise the dual synthesis strategy in terms of bimetallic inorganic building blocks and sulfur containing organic ligand. A novel sulfur-containing bimetallic metal organic framework (Fe2Co-TPDC) with two types of 4-fold meso-helical structures has been successfully synthesized. Benefitting from the uniform distribution of active sulfur sites and the structural stability of the mixed-metallic method, Fe2Co-TPDC can efficiently prevent a shuttle behavior of sulfur and endow a commendable specific capacity. As far as we know, this is the first time that a sulfur-containing bimetallic crystalline MOF with helical structure and prominent specific capacity and remarkable cycling stability has served as an electrode material for LIBs.
Nitrogen-doped flexible carbon foam was used to fabricate a lithium sulfur battery. The stability and rate performance of the battery were evaluated. The battery with carbon foam calcined at 800 degrees C displayed superior stability compared with other tested batteries. Battery performance was closely related to the foam structure and component. However, good rate performance was achieved with the foam calcined at 800 degrees C. Cathodes with carbon foam calcined at different temperatures had diverse effects on the batteries.
The particularly basic phosphines 1a-c readily form isolable, zwitterionic Lewis base adducts with SO2 that were fully characterized including by X-ray diffraction studies. Computational and reactivity studies show that these adducts readily release SO at room temperature driven by the formation of the corresponding phosphine oxides.
By calcination, a sulfur vacancy rich CdS based composite photocatalyst with graphitic carbon nitride (g-C3N4) as a matrix has been synthesized successfully from a tetranuclear Cd-S cluster assembled supramolecular network. In this photocatalyst (CdS@g-C3N4), CdS nanoparticles with a size of about 5 to 8 nm disperse homogenously in the g-C3N4 matrix. During calcination, some coordinated nitrogen atoms dope in the lattice of CdS and replace sulfur atoms, which generates a large number of sulfur vacancies. Under visible light irradiation, CdS@g-C3N4 exhibits excellent H-2 production activity with a rate achieving as high as 19.88 mmol g(-1) h(-1) in the absence of a Pt cocatalyst. Its H-2 production ability remains stable for 30 h, which does not decay. Besides H-2 production, CdS@g-C3N4 also shows excellent photocatalytic activity for Volatile Organic Compound (VOC) degradation. For a photocatalyst, chemical content plays an important role in its performance. Here, the influence of sulfur vacancies on H-2 production and VOC degradation is discussed in detail. We expect that the sulfur vacancy rich CdS@g-C3N4 can act as an efficient material for H-2 production and indoor air purification.
Singly charged As2n+1 ion clusters (n = 2-11) were generated from elemental arsenic by negative-ion laser-ablation mass spectrometry. The overall abundance of the gaseous As ions generated upon laser irradiation was enhanced nearly a hundred times when As-bearing samples were admixed with sulfur. However, sulfur does not act purely as an inert matrix: irradiating arsenic-sulfur mixtures revealed a novel pathway to generate and detect a series of AsSn](-) clusters (n = 2-6). Intriguingly, the spectra recorded from As2O3, NaAsO2, Na3AsO4, cacodylic acid and 3-amino-4-hydroxyphenylarsonic acid together with sulfur as the matrix were remarkably similar to that acquired from an elemental arsenic and sulfur mixture. This result indicated that arsenic sulfide cluster-ions are generated directly from arsenic compounds by a hitherto unknown pathway. The mechanism of elemental sulfur extracting chemically bound arsenic from compounds and forming AsSn](-) clusters is enigmatic; however, this discovery has a practical value as a general detection method for arsenic compounds. For example, the method was employed for the detection of As in its minerals, and for the imaging of arsenic distribution in minerals such as domeykite. LDI-MS data recorded from a latent image imprinted on a piece of paper from a flat mineral surface, and wetting the paper with a solution of sulfur, enabled the localization of arsenic in the mineral. The distribution of As was visualized as false-color images by extracting from acquired data the relative intensities of m/z 139 (AsS2-) and m/z 171 (AsS3-) ions.
The reactions between metal borohydrides and elemental sulfur are investigated in situ during thermal treatment and are found to be highly exothermic (up to 700 J g(-1)). These reactions are exceptionally rapid, occurring below 200 degrees C, also resulting in the sudden release of substantial quantities of hydrogen gas. For NaBH4 this hydrogen release is pure, with no detectable levels of H2S or B2H6. The reaction results in the formation of an array of metal-boron-sulfur compounds. These MBH4-S compounds are interesting for possible uses in high energy applications (fuels or explosives), hydrogen generation, and metal-boron-sulfur precursors.
BaSF was synthesised by a solid state reaction at high temperature and its crystal structure was determined thanks to X-ray diffraction on a single crystal. This transparent yellow fluorochalcogenide has an inter-growth structure built from the stacking of fluorite type layers and sulfur layers. In BaSF sulfur atoms form dimers with interatomic distances as short as 2.1074(10) angstrom. DFT calculations confirm that this compound is a band insulator with the Fermi level lying in between the antibonding pi* and sigma* molecular orbitals of the sulfur dimers. Reflectance measurements show that the optical band gap of BaSF is about 2.7 eV in good agreement with the value found from DFT calculations.
The redox flow battery (RFB) is a promising technology for the storage of electric energy. Many commercial RFBs are often based on acidic vanadium electrolyte solutions that have limitations regarding stability and energy density. Here, a new approach is presented that is inspired by nature's electron storage, i. e. iron- sulfur clusters Fe4S4(SR)(4)](2-). In combination with imidazolium cations, new ionic liquid electrolyte materials were obtained and characterized with regard to their physico- and electrochemical properties. For flow battery tests, the bromide/ bromine redox- couple was used in the second half cell in an ionic liquid solution. In these measurements, liquid iron-sulfur clusters show high coulombic (> 95%) and energy (69%) efficiencies combined with a high theoretical energy density (88 W h L-1).
Practical applications of lithium-sulfur (Li-S) batteries are greatly limited by rapid capacity attenuation caused by polysulfide shuttling. Functional modification of separators has been proved to be an efficient strategy to restrain the polysulfide shuttling. Herein, we present a short overview of the recent advances in the development of multi-functional separators, and provide an outlook on the promising approaches for the construction of reliable Li-S batteries.
Four pyridine-bridged bis(1,2,3-triazoles) A/B and C/D have been prepared by "click" reactions. Methylations/ethylations of A/B and C/D employing Meerwein's salts led to the formation of the corresponding dicationic salts 1/2 and 3/4 with pyridine moieties surviving from the alkylations. Interestingly, the reactions of "N-linked" salts 1/2 with K2CO3 in the presence of elemental sulfur did not yield the mesoionic carbene-sulfur betaine adducts but unexpectedly afforded 1,5-disubstituted triazoles 5/6, which may produce pyridine thioaldehydes as by-products. In contrast, in the case of "C-linked" salts 3/4, the reactions to synthesize carbene-sulfur zwitterions 9/10 proceeded smoothly. Employing a silver-carbene transfer protocol with salt 3 as the precursor, the CNC]-type palladium pincer complex 8 was synthesized, the solid-state structure of which was determined by X-ray diffraction analysis. Complex 8 underwent ligand substitutions with silver carboxylates producing the acetato complex 11 and trifluoroacetato complex 12. All newly synthesized pincer complexes were employed to test their catalytic activities in Mizoroki-Heck reactions. Positive mercury drop tests implied that the pincer-type complexes do not survive under the conditions of catalysis, owing to which no conclusions can be drawn regarding the catalyst variation or substrate scope.