水热氧化改性碳纸电极在全钒氧化还原电池中的应用

为了提高钒氧化还原电池电极的活性,在180°C下将碳纸电极与过氧化氢的硫酸溶液置于有聚四氟乙烯内衬的不锈钢反应釜中进行不同时间的水热酸氧化处理.水的接触角测试表明,随着处理时间从6h调整至18h,处理前后碳纸电极的接触角也从120.0°降低至100.8°,尤其是经过12h处理的样品的接触角最小,这说明在此条件下处理过的碳纸的亲水性得到了提高.而傅里叶变换红外测试表明,羰基和羧基等含氧基团被成功地引入到了碳纸电极中.使用扫描电镜,循环伏安,电化学阻抗以及充放电技术分别检测了处理前后样品的表面形貌及电化学性能.V(IV)/V(V)氧化还原电对在这些处理过的样品上表现出较大的活性.用处理12h的碳纸电极组装的单电池性能优异,在30mA·cm-2的电流密度下能量效率达到了80%,相应的电流效率和电压效率分别为96%和84%.

Modification of Carbon Paper Electrode via Hydrothermal Oxidation Applied in the Vanadium Redox Battery

To improve the electrochemical activity of electrodes in the vanadium redox battery,carbon paper electrode was treated with a hydrogen peroxide and sulfuric acid solution,according to the hydrothermal acid oxidation method,in a Teflon-lined stainless steel autoclave over different time periods at 180 ℃.The water contact angle test showed that the contact angle of treated carbon paper samples changed from 120.0° to 100.8° by adjusting the treatment time from 6 to 18 h.Furthermore,a treatment time of 12 h resulted in the lowest contact angle observed,indicating that the wetting property of the carbon paper had been enhanced under these treatment conditions.Fourier transformation infrared spectroscopy results showed that oxygen-containing groups,such as the carbonyl and carboxyl groups,had been successfully introduced to the carbon papers.Scanning electron microscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and charge-discharge tests were carried to characterize the surface topography and electrochemical properties of the carbon papers.The treated samples showed high activity in the redox reactions of V(IV)/V(V).A single-cell employing carbon paper was treated for 12 h as an electrode and exhibited an excellent performance.The energy efficiency reached 80% at a current density of 30 mA · cm-2.The corresponding coulombic and voltage efficiencies were 96% and 84%,respectively.