Na_(3)AlF_(6)-SiO_(2)熔盐中Si(Ⅳ)的电化学行为  

Electrochemical behavior of Si(Ⅳ)in Na_(3)AlF_(6)-SiO_(2) melt

作　　者：何林 高运明[1,2] 秦庆伟[1,2] 李光强[1,2] He Lin;Gao Yunming;Qin Qingwei;Li Guangqiang(Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,China;Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室,湖北武汉430081 [2]武汉科技大学钢铁冶金新工艺湖北省重点实验室,湖北武汉430081

出　　处：《武汉科技大学学报》2021年第6期423-428,共6页Journal of Wuhan University of Science and Technology

基　　金：国家自然科学基金资助项目(51174148).

摘　　要：利用Y 2O_(3)稳定的ZrO_(2)固体电解质(YSZ)管,集成构建Pt,O_(2)(air)│YSZ作为参比和辅助电极的三电极新型电化学池,采用循环伏安法和计时电流法等电化学测试技术,研究在完全无碳条件下1323 K温度时Na 3AlF_(6)-5%SiO_(2)熔盐体系中Si(IV)在Ir丝工作电极上的电化学还原行为。结果表明,Si(IV)电化学还原是单步骤4电子转移不可逆过程,其电极反应过程受扩散控制,还原产物Si不可溶。Si(IV)的还原峰电位在-1.6~-1.7 V之间,电荷传递系数在0.21~0.39范围,Si(IV)扩散系数在10-7 cm 2/s数量级。Si(IV)扩散系数偏小的原因可能是Na 3AlF_(6)-SiO_(2)熔体中存在来自于YSZ管溶解或脱落的Y、Zr的氧、氟化合物以及因反应逸出SiF 4而导致的SiO_(2)浓度降低。A novel three-electrode electrochemical cell with Pt,O_(2)(air)∣YSZ as reference and counter electrodes was constructed by Y 2O_(3) stabilized ZrO_(2) solid electrolyte(YSZ)tube.By using cyclic voltammetry and chronoamperometry electrochemical measuring techniques,the electrochemical reduction behavior of Si(IV)on Ir wire working electrode in Na 3AlF_(6)-5%SiO_(2) melt at 1323 K was investigated under carbon-free conditions.The results show that the electrochemical reduction of Si(IV)is an irreversible process with 4 electron transfer in one single-step,the electrode reaction process is controlled by diffusion,and the reduction product Si is insoluble.The reduction peak potential of Si(IV)is between-1.6~-1.7 V,the charge transfer coefficient is between 0.21~0.39,and the Si(IV)diffusion coefficient is on the order of 10-7 cm 2/s.The low diffusion coefficient may be due to the presence of oxygen and fluorine compounds of Y and Zr from the dissolution or shedding of the YSZ tube in the Na 3AlF_(6)-SiO_(2) melt and the decrease of the SiO_(2) concentration caused by volatilization of formed SiF 4 in Na 3AlF_(6)-SiO_(2) melt.

关 键 词：Si(Ⅳ) SiO_(2) 冰晶石熔盐 循环伏安 计时电流 电化学行为 ZrO_(2)固体电解质 

分 类 号：TQ151.5[化学工程—电化学工业]