含氧化还原活性基团的苯醌衍生物,在水系质子电池里是一种比容量高、资源丰富的理想电极材料,然而其高溶解性和低的工作电压不利于质子电池的循环稳定性和能量密度的提升,引入吸电子基团不仅可以降低其LUMO能量来提升其反应电位,还可以...含氧化还原活性基团的苯醌衍生物,在水系质子电池里是一种比容量高、资源丰富的理想电极材料,然而其高溶解性和低的工作电压不利于质子电池的循环稳定性和能量密度的提升,引入吸电子基团不仅可以降低其LUMO能量来提升其反应电位,还可以一定程度上抑制其溶解来提升稳定性。因此,通过电化学研究并对比了3种不同的苯醌化合物作为质子电池的电极材料,研究了不同氯取代情况造成的影响。其中四氯取代的四氯苯醌(4Cl-BQ)反应电位最高(0.51 V vs.Ag/AgCl),多电子氧化还原反应机制使其在水系质子电池里具有158 mAh/g的出色容量和高的倍率性能,并且氯取代有效抑制了溶解,在1 A/g的电流密度下也能稳定循环超过1200圈,显示出优异的性能。最后通过探究了电荷的快速反应动力学特征解释了出色的倍率性能。该研究表明,通过引入-Cl基团改进的4Cl-BQ,能进一步提升其在电池里综合性能,是一种极具发展潜力的水系质子电池材料。展开更多
Quinones are common organic compounds frequently used as model dissolved organic matters in water, and their redox properties are usually characterized by either electrochemical or spectroscopic methods separately. In...Quinones are common organic compounds frequently used as model dissolved organic matters in water, and their redox properties are usually characterized by either electrochemical or spectroscopic methods separately. In this work, electrochemical methodology was combined with two fluorescence spectroelectrochemical techniques, cyclic voltafluorescence spectrometry （CVF） and derivative cyclic voltafluorescence spectrometry （DCVF）, to determine the electrochemical properties of p-benzoQuinone in dimethvl sulfoxide, an aprotic solution. The CVF results show that the electrochemical reduction ofp-benzoquinone resulted in the formation of radical anion and dianion, which exhibited a lower fluorescence intensity and red-shift of the emission spectra compared to that of p-benzoauinone. The fluorescence intensity was found to vary along with the electrochemical oxidation and reduction ofp-benzoquinone. The CVF and DCVF results were in good consistence. Thus, the combined method offers a powerful tool to investigate the electrochemical process of p-benzoquinone and other natural organic compounds.展开更多
A novel simple, sensitive, rapid, direct, and spectrophotometry-based procedure was investigated to determine Th(IV) at trace amounts. The new method is based on Th(IV) chelation with 3,6-dichloro-2,5-dihydroxy-l,4-be...A novel simple, sensitive, rapid, direct, and spectrophotometry-based procedure was investigated to determine Th(IV) at trace amounts. The new method is based on Th(IV) chelation with 3,6-dichloro-2,5-dihydroxy-l,4-benzoquinone(DDBQ). The reagent reacts with Th(IV) in 0.1 M HCl to form an orange 1:2 complex. The stability constant value is 6.62×10~4 for the Th(IV)complex. The Th(IV)-DDBQ obtained shows one peak with a maximum at about 346 nm. The chelate forms immediately and the absorbance remains stable for over24 h. Beer's law was obeyed in the concentration range0–10 μg mL^(-1). The molar absorptivity and Sandell's sensitivity were 4.4×10~4 L mol^(-1)cm^(-1) and 0.0053 μg cm^(-2), respectively. Different analytical parameters were tested in detail. Interfering ion(cations and anions) effects were tested. Methods for Th(IV) determination by second and third-derivative spectrophotometry were also introduced at about 344 and 341 nm, respectively. These two derivative orders offer the feature of sensitivity without the necessity for solvent extraction,heating, or pre-concentration steps. Finally, the methods were successfully utilized for Th(IV) determination in monazite, environmental water, and wastewater samples.展开更多
文摘含氧化还原活性基团的苯醌衍生物,在水系质子电池里是一种比容量高、资源丰富的理想电极材料,然而其高溶解性和低的工作电压不利于质子电池的循环稳定性和能量密度的提升,引入吸电子基团不仅可以降低其LUMO能量来提升其反应电位,还可以一定程度上抑制其溶解来提升稳定性。因此,通过电化学研究并对比了3种不同的苯醌化合物作为质子电池的电极材料,研究了不同氯取代情况造成的影响。其中四氯取代的四氯苯醌(4Cl-BQ)反应电位最高(0.51 V vs.Ag/AgCl),多电子氧化还原反应机制使其在水系质子电池里具有158 mAh/g的出色容量和高的倍率性能,并且氯取代有效抑制了溶解,在1 A/g的电流密度下也能稳定循环超过1200圈,显示出优异的性能。最后通过探究了电荷的快速反应动力学特征解释了出色的倍率性能。该研究表明,通过引入-Cl基团改进的4Cl-BQ,能进一步提升其在电池里综合性能,是一种极具发展潜力的水系质子电池材料。
基金Acknowledgements The authors wish to thank the National Natural Science Foundation of China （Grant Nos. 21505074 and 21477120） and the Natural Science Foundation of Jiangsu Province （BK20140781） for partial support of this study.
文摘Quinones are common organic compounds frequently used as model dissolved organic matters in water, and their redox properties are usually characterized by either electrochemical or spectroscopic methods separately. In this work, electrochemical methodology was combined with two fluorescence spectroelectrochemical techniques, cyclic voltafluorescence spectrometry （CVF） and derivative cyclic voltafluorescence spectrometry （DCVF）, to determine the electrochemical properties of p-benzoQuinone in dimethvl sulfoxide, an aprotic solution. The CVF results show that the electrochemical reduction ofp-benzoquinone resulted in the formation of radical anion and dianion, which exhibited a lower fluorescence intensity and red-shift of the emission spectra compared to that of p-benzoauinone. The fluorescence intensity was found to vary along with the electrochemical oxidation and reduction ofp-benzoquinone. The CVF and DCVF results were in good consistence. Thus, the combined method offers a powerful tool to investigate the electrochemical process of p-benzoquinone and other natural organic compounds.
文摘A novel simple, sensitive, rapid, direct, and spectrophotometry-based procedure was investigated to determine Th(IV) at trace amounts. The new method is based on Th(IV) chelation with 3,6-dichloro-2,5-dihydroxy-l,4-benzoquinone(DDBQ). The reagent reacts with Th(IV) in 0.1 M HCl to form an orange 1:2 complex. The stability constant value is 6.62×10~4 for the Th(IV)complex. The Th(IV)-DDBQ obtained shows one peak with a maximum at about 346 nm. The chelate forms immediately and the absorbance remains stable for over24 h. Beer's law was obeyed in the concentration range0–10 μg mL^(-1). The molar absorptivity and Sandell's sensitivity were 4.4×10~4 L mol^(-1)cm^(-1) and 0.0053 μg cm^(-2), respectively. Different analytical parameters were tested in detail. Interfering ion(cations and anions) effects were tested. Methods for Th(IV) determination by second and third-derivative spectrophotometry were also introduced at about 344 and 341 nm, respectively. These two derivative orders offer the feature of sensitivity without the necessity for solvent extraction,heating, or pre-concentration steps. Finally, the methods were successfully utilized for Th(IV) determination in monazite, environmental water, and wastewater samples.
