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The solvothermal synthetic exploration of the Bi–S–halogen phase space resulted in the synthesis of two bismuth sulfohalides with common structural motifs. Bi 13 S 18 I 2 was confirmed to have the previously reported composition and crystal structure. In contrast, the bromide analogue was shown to have a formula of neither Bi 19 S 27 Br 3 nor Bi 13 S 18 Br 2 , in contrast to the previous reports. The composition, refined from single crystal X-ray diffraction and confirmed by elemental analysis, high-resolution powder X-ray diffraction, and total scattering, is close to Bi 13 S 17 Br 3 due to the partial S/Br substitution in the framework. Bi 13 S 18 I 2 and Bi 13 S 17 Br 3 are n -type semiconductors with similar optical bandgaps of ∼0.9 eV but different charge and heat transport properties. Due to the framework S/Br disorder, Bi 13 S 17 Br 3 exhibits lower thermal and electrical conductivities than the iodine-containing analogue. The high Seebeck coefficients and ultralow thermal conductivities indicate that the reported bismuth sulfohalides are promising platforms to develop novel thermoelectric materials.more » « less
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Abstract Polymeric membrane‐based gas separation technology has significant advantages compared with traditional amine‐based CO2separation method. In this work, SEBS block copolymer is used as a polymer matrix to incorporate triethylene oxide (TEO) functionality. The short ethylene oxide segment is chosen to avoid crystallization, which is confirmed by differential scanning calorimetry and wide‐angle X‐ray scattering characterizations. The gas permeability results reveal that CO2/N2selectivity increased with increasing content of TEO functional group. The highest CO2permeability (281 Barrer) and CO2/N2selectivity (31) were obtained for the membrane with the highest TEO incorporation (57 mol%). Increasing the TEO content in these copolymers results in an increase in CO2solubility and a decrease in C2H6solubility. For example, as the grafted TEO content increased from 0 to 57 mol%, the CO2solubility and CO2/C2H6solubility selectivity increased from 0.72 to 1.3 cm3(STP)/cm3atm and 0.47 to 1.3 at 35°C, respectively. The polar ether linkage in TEO‐grafted SEBS copolymers exhibits favorable interaction with CO2and unfavorable interaction with nonpolar C2H6, thus enhancing CO2/C2H6solubility selectivity.
