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BACKGROUND The conventional method for the measurement of sulfur isotopes in sulfate includes mainly barite conversion coupled with dual-inlet SO2 methods. These methods are facile and reliable. However, the large amounts of samples, the length of time needed, the laborious experimental work, and complicated preprocessing are impractical for the development direction of micro-analysis. OBJECTIVES To develop a method for determination of sulfur isotope compositions in gypsum directly through continuous flow elemental analyzer-isotope mass spectrometry (EA-IRMS). METHODS Two different preparation methods were used. (1) Direct measurement of sulfur isotopes was carried out by mixing calcium sulfate powder with V2O5 in a tin cup using EA-IRMS. (2) Calcium sulfate was fully dissolved in deionized water. The precipitation reagent BaCl2 was added to the liquid in which the calcium sulfate sample was dissolved. After the precipitated barium sulfate was filtered out, it was washed 2 to 3 times with deionized water. Samples were dried and mixed with V2O5 in a sealed tin cup and then determined by mass spectrometry. RESULTS The δ34S values of 13 gypsum samples ranged from -20‰ to -30‰, and the results from replicate measurements were compared for these two methods, yielding the absolute difference in δ values were 0.0-0.2 permil, indicating that the sulfur isotope ratios of the same sample were basically identical. CONCLUSIONS Compared with the conventional analysis method, the application of 'no pretreatment' to analyze the sulfur isotopes of gypsum was conducted successfully. Adding V2O5 to samples directly, during the process of instantaneous combustion, the oxygen in calcium sulfate are substituted by the external oxygen in V2O5 and oxygen gas, and the obtained oxygen of SO2 gas is uniform. Therefore, sulfur isotope ratios of SO2 can completely represent those of the calcium sulfate, making it unnecessary for oxygen isotope correction. The direct online analysis of sulfur isotopes in calcium sulfate samples using EA-IRMS is verified to be feasible.

Exploring better electrochemical energy storage devices is a great challenge. Lithium‐ion capacitors have attracted much attention because they combine the advantages of Li‐ion batteries and supercapacitors, but the mismatch between the kinetics and capacity of the cathode and anode is still an extraordinary gap. In order to address this issue, a cubic‐phase perovskite fluoride KMnF3 via a simple and safe coprecipitation way is synthesized. The KMnF3 electrode exhibits a cubic‐phase structure and a pseudocapacitive kinetics by X‐ray diffractometer and cyclic voltammetry. The high specific capacity (189 mAh g−1 at 0.1 A g−1 for 500 cycles) and fast pseudocapacitive control dynamics (at the sweep speed of 0.2 mV s−1, the pseudocapacitance ratio is 62.12%) can be demonstrated in half cell, while the b‐value is up to 0.95. Further assembled with activate carbon to form lithium‐ion capacitors (LICs), KMnF3//AC delivers high energy density (24 Wh kg−1), high power density (3900 kW kg−1), and long cycle life over 4000 cycles. The findings shed lights on developing advanced electrode materials for high‐performance electrochemical LICs. [ABSTRACT FROM AUTHOR]

Herein, CoF2 was synthesized by a solvothermal method. The characterization results of the phase and morphology of the sample show that it was successfully synthesized and its morphology is composed of micron particles with uneven size and shape. The electrochemical test results of SCs in different electrolytes show that CoF2 has electrochemical activity only in alkaline electrolytes. Notably, the electrochemical behavior of CoF2 in LiOH solution is different from that in other alkaline solutions in that charge‐discharge curve has a quasi‐isosceles triangle shape and the CV curve has no obvious redox peak. That is, it has pseudocapacitance behavior in LiOH. Furthermore, CoF2 as catalyst for HER requires an overpotential of only 168 mV to obtain current density of 10 mA cm−2 and a Tafel slope of 116 mV dec−1 in 1 M KOH solution. This research provides a novel way to explore excellent performance electrode materials for SC and HER. [ABSTRACT FROM AUTHOR]

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