有机硫化合物在锂硫电池中的应用

锂硫电池具有理论能量密度高、环境友好和成本低等优点,有望成为替代锂离子电池的新一代储能系统。然而,锂硫电池充放电产物的绝缘性、可溶性多硫化锂的穿梭效应、硫正极体积膨胀及锂枝晶的不可控生长,严重影响了锂硫电池的实际容量发挥和循环稳定性。为解决上述问题,采用有机硫化合物来替代单质硫作为正极材料是有前途的策略。调控有机硫化合物的硫链、碳链及其相互作用,可改变其电化学反应过程,提高离子/电子电导,抑制穿梭效应。有机硫化合物作为电解液添加剂,可调控硫正极的反应过程并保护金属锂负极,作为聚合物电解质的改性链段可加速锂离子传导。本综述对有机硫化合物在锂硫电池的正极、电解液添加剂和固态电解质中的应用研究进展进行详细的阐述。将有机硫化合物的结构、反应机理和电化学性质联系起来,为解决锂硫电池存在的问题提供见解。最后,提出高性能有机硫化合物的设计合成和机理研究思路,以期实现可实用化的锂硫电池。

Single-atom catalysts for metal-sulfur batteries:Current progress and future perspectives

Metal-sulfur batteries are recognized as a promising candidate for next generation electrochemical energy storage systems owing to their high theoretical energy density,low cost and environmental friendliness.However,sluggish redox kinetics of sulfur species and the shuttle effect lead to large polarization and severe capacity decay.Numerous approaches from physical barrier,chemical adsorption strategies to electrocatalysts have been tried to solve these issues and pushed the rate and cycle performance of sulfur electrodes to higher levels.Most recently,single-atom catalysts(SACs)with high catalytic efficiency have been introduced into metal-sulfur systems to achieve fast redox kinetics of sulfur conversion.In this review,we systematically summarize the current progress on SACs for sulfur electrodes from aspects of synthesis,characterization and electrochemical performance.Challenges and potential solutions for designing SACs for high-performance sulfur electrodes are discussed.

Study of selective hydrogenation of biodiesel in a DBD plasma reactor

In order to achieve the selective hydrogenation of biodiesel at room temperature and under normal pressure,we researched the upgrading of soybean biodiesel using a dielectric-barrier discharge(DBD)reaction system.Using Raney-Ni as the hydrogenation catalyst,the effects of the operating parameters on the hydrogenation depth and the selectivity of biodiesel were systematically analyzed.The results show that the polyunsaturated components in soybean methyl ester were reduced by 57.04%,and that the polyunsaturated components were hydrogenated to monounsaturated components with a selectivity of 77.75%.Based on the gas chromatography and mass spectrometry(GC-MS)test results,we established a kinetic model for biodiesel hydrogenation.A comparison of the calculated and experimental results shows that the hydrogenation of the biodiesel can be described by a quasi first-order reaction model.The calculated reaction rate constants indicate that under DBD plasma reaction conditions,the hydrogenation of biodiesel has high selectivity for the formation of monounsaturated components.

Role of Catalytic Materials on Conversion of Sulfur Species for Room Temperature Sodium–Sulfur Battery

Room temperature sodium–sulfur(RT Na-S)battery with high theoretical energy density and low cost has spurred tremendous interest,which is recognized as an ideal candidate for large-scale energy storage applications.However,serious sodium polysulfide shutting and sluggish reaction kinetics lead to rapid capacity decay and poor Coulombic efficiency.Recently,catalytic materials capable of adsorbing and catalyzing the conversion of polysulfides are profiled as a promising method to improve electrochemical performance.In this review,the research progress is summarized that the application of catalytic materials in RT Na-S battery.For the role of catalyst on the conversion of sulfur species,specific attention is focused on the influence factors of reaction rate during different redox processes.Various catalytic materials based on lightweight and high conductive carbon materials,including heteroatom-doped carbon,metals and metal compounds,single-atom and heterostructure,promote the reaction kinetic via lowered energy barrier and accelerated charge transfer.Additionally,the adsorption capacity of the catalytic materials is the key to the catalytic effect.Particular attention to the interaction between polysulfides and sulfur host materials is necessary for the exploration of catalytic mechanism.Lastly,the challenges and outlooks toward the desired design of efficient catalytic materials for RT Na-S battery are discussed.

Crucial role of iron plaque on thallium uptake by rice plant

Iron plaque is a Fe-containing oxide film produced by the oxidation of Fe(II)in the rice root system under the combined action of oxygen infiltration and other microorganisms.Owing to its special surface structure and physio-chemical properties,the iron plaque has a strong absorption capacity for a variety of heavy metal ions.This study aimed to first investigate the effects of Fe species on the geochemical fractionation of Tl in typical paddy soil systems affected by industrial activities,followed by pot culture experiments to probe the effects of Fe species on the uptake and translocation of Tl in rice plants.The results of field work preliminarily showed that iron at different valences affected the conversion of the Tl geochemical fraction in the soil.Oxidizable Tl exerted significant positive correlation relationships with Fe2+and negative correlation relationships with Fe3+,while reducible Tl only displayed a positive correlation with Fe3+.Further analysis by pot culture experiments revealed that the contents of Fe were significantly positively correlated with Tl contents in Fe plaque(R2=0.529).In contrast,the water-soluble Tl contents in the soil were significantly negatively correlated with the contents of Fe(R2=–0.90,p<0.05).It suggests that the iron plaque promoted the absorption and fixation of Tl on the root surface of rice plants,causing Tl to accumulate in the iron plaque.Besides,the Tl content in the Fe plaque on the root surface of rice plants was greater than that in the above-ground tissues,which indicates that most Fe plaque exerts a certain degree of inhibition on Tl migration into the above-ground tissues of rice plants.All these findings indicate that Fe film is also an important carrier of Tl transfer in the soil–rice plant system,which provides new scientific support for the remediation of typical Tl-contaminated rice fields.

牙龈卟啉单胞菌介导慢性肾病发生发展的研究进展

慢性肾病(CKD)是临床常见泌尿系统疾病之一,发病率近年来呈逐年升高趋势,已经成为全球重大公共卫生问题。牙周炎是中老年人群高发的口腔疾病,是导致成人牙齿缺失的主要原因,研究证明其与全身多种疾病的发生、发展密切相关。最新研究表明,牙周炎的主要致病菌——牙龈卟啉单胞菌,可能是CKD的重要风险因素。在肾功能方面,患有牙周炎的CKD人群较牙周健康的CKD人群差,而通过牙周炎治疗则可以减小两者的肾功能差异。多项研究表明,牙龈卟啉单胞菌可以借助多种方式在CKD的发生、发展中发挥重要作用。牙龈卟啉单胞菌可以通过破坏肾脏上皮的完整性,加重肾脏的炎症反应,加重肾脏组织氧化应激损伤等方式促进CKD的发生、发展。本文系统梳理了牙龈卟啉单胞菌在CKD发生、发展方面的相关研究,有助于全面认识两者的相互关系及其致病机制。