Effect of substituent position on electrodeposition, morphology, and capacitance performance of polyindole bearing a carboxylic group. (10th September 2015) - Ma, Xiumei
Graphical abstract: The effect of carboxylic substituent position on the electrodeposition, morphology, and capacitance performance of substituted polyindole derivative nanowires were investigated for the first time. The results indicated that the position of the carboxylic substitution had remarkable impact on the diameter size and capacitance performance of these polymer nanowires. Furthermore, these polymers with high specific capacitance and excellent stability would be strong candidates as electrode material for supercapacitor. Highlights: Three carboxylic group substituted polyindole nanowires were synthesized. Effect of substituent position on their morphology was firstly reported. Effect of substituent position on their capacitance performance was reported. The three polyindole nanowires showed excellent capacitance performance. Abstract: In this paper, the effects of carboxylic substituent position on their electrodeposition, morphology and capacitance properties were investigated for the first time. The results indicated that three carboxylic group substituted polyindole derivatives nanowires, namely poly(indole-5-carboxylic acid) (5-PICA), poly(indole-6-carboxylic acid) (6-PICA), and poly(indole-7-carboxylic acid) (7-PICA), were successfully electrochemically synthesized in acetonitrile containing 0.1 M LiClO4, whereas poly(indole-4-carboxylic acid) (4-PICA) was difficult to be obtained. For 5-PICA, 6-PICA and 7-PICA nanowires, the diameters of nanowires demonstrated by the scanning electron microscopy were about 100 nm, 50 nm, and 30 nm, respectively. Their specific capacitances and energy densities in 1.0 M H2 SO4 solution were measured to be 355 F g −1, 383 F g −1, 430 F g −1 at 2.5 A g −1 and 40.0, 43.1, 48.3 Wh kg −1 at a power density of 1125 W kg −1, respectively, and their specific capacitance retentions after 1000 charge/discharge processes reached 94.5%, 95.1%, and 96%, respectively. These results indicated that the position of the carboxylic substituent had remarkable impacts on the diameter sizes and electrochemical properties of these polymer nanowires. Furthermore, the three polymers with high specific capacitance and excellent stability would be strong candidates as electrode material for supercapacitors.