电化学氧化改性石墨毡电极对VO^(2+)/VO_2^+电对的催化活性

Catalysis of graphite felt electrode treated with electrochemical oxidation for VO^(2+)/VO_2^+

采用循环伏安和恒流充放电试验研究了电化学氧化改性石墨毡对VO2+/VO+2电对的催化活性,并利用XPS、FT-IR、SEM、BET对改性前后石墨毡碳纤维表面O/C、官能团变化、形貌和比表面积进行比较。结果表明,电化学处理后,石墨毡表面的O/C比例由0.085增加至0.15,增加的主要是C OOH官能团。石墨毡碳纤维表面被刻蚀,比表面积有所增大。采用改性的石墨毡作为电极组装的全钒液流电池在50mA/cm2电流密度下,电压效率达75.99%,电流效率达96.79%,经多次循环性能稳定。电极活性的提高归因于碳纤维表面C OOH官能团数目的增加和比表面积的增大。

The catalysis of graphite felt electrode treated with electrochemical oxidation for VO^2＋/VO2^＋ has been investigated by cyclic voltammetry and constant current charge-discharge measurements. The O/C rate, functional groups, structure, and surface area on the surface of graphite felt have been compared with untreated samples by XPS, FT-IR, SEM and BET. The results demonstrate that electrochemical activity of the graphite felt in vanadium electrolyte enhances with the degree of oxidation. O/C rate augments from 0. 085 up to 0.15, due to the increasing functional groups of COOH. The surface of graphite felt was eroded by electrochemical oxidation, resulting in the surface area increase. The electrochemical test results suggest that the vanadium redox flow battery with modification electrode could deliver specific performance at a current density of 50mA/cm^2, the current efficiency is above 96.79 %, and voltage efficiency above 75.99 %. The improvement of electrochemical activity for the electrode is ascribed to the increase of the number of COOH group and special surface.