La_(1-x)Sr_xNi_(1-y)Fe_yO_3(型钙钛矿双功能氧电极的电化学性能研究  

Study on the Electrochemical Properties of La_(1-x)Sr_xNi_(1-y)Fe_yO_3 Bifunctional Oxygen Electrodes

作　　者：宋世栋[1] 唐致远[1] 潘丽珠[1] 南俊民[2] 

机构地区：[1]天津大学化工学院应用化学系,天津300072 [2]华南师范大学化学系,广州510631

出　　处：《化学学报》2005年第5期363-371,共9页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20273047);教育部博士点重点基金(No.20020056045)资助项目.

摘　　要：采用溶胶-凝胶法制备了一系列La_(1-x)Sr_xNi_(1-y)Fe_yO_3(x=0,0.1,0.2,0.5;y=0～1.0)型的钙钛矿催化剂,以活性碳为载体,PTFE乳液为粘接剂制备双功能氧电极.对催化剂进行了XRD结构分析以及SEM分析和BET比表面积测量.采用三电极体系测试了氧电极的稳态极化曲线和电化学交流阻抗谱并对其阴极极化和阳极极化的交流阻抗谱图进行分析.通过等效电路的拟合研究了该系列双功能氧电极氧还原反应的工作机理.实验表明对于LaNiO3化合物,B位掺杂可显著提高催化剂的电催化性能;电极氧还原反应的极化主要由电荷转移反应和Nernstian扩散过程造成.通过各个电极对于催化分解H2O2的分解速率常数的测定得知,Ni离子对于催化H2O2分解反应的活性大于Fe离子,继续在对于氧还原反应和氧析出反应都具有较高电催化活性的LaNi0.8Fe0.2O3催化剂上进行A位掺杂Sr离子后显著提高了催化剂分解H2O2的催化活性,主要是因为氧空位的增多和金属离子d电子含量的降低有利于催化分解H2O2的活性的提高,但由于氧空位的增多导致催化剂电导率的降低,所以其电催化活性降低了.通过多圈循环伏安扫描的测试,催化剂LaNi0.8Fe0.2O3有很好的稳定性.A series of novel La1-xSrxNi1-yFeyO3 (x=0, 0.1, 0.2, 0.5; y=0 similar to 1.0) perovskite oxides were prepared by sol-gel method and characterized by XRD, SEM and BET measurement. The activity of PTFE bonded bifunctional oxygen electrodes made by the perovskite-type catalyst dispersed on active carbon was investigated using steady polarization curves and electrochemical impedance spectroscopy (EIS) method. The impedance spectra of both cathodic and anodic polarization were analyzed. The electrochemical parameters of the oxygen reduction reaction were obtained by fitting the experimental impedance data to an equivalent circuit containing two Nernstian diffusion terms. The results show that the oxygen reduction activity was improved by doping Fe3+ ions on site B of LaNiO3 oxides. But doping Sr2+ ions on site A could impair the effect because the ordering level of oxygen vacancy and electrode resistance were increased. The decomposition reaction rate of H2O2 catalyzed by perovskite catalysts was examined. The data showed that the catalytic activity of Ni ion was higher than that of Fe ion and when doped with Sr ion the catalytic activity of decomposition reaction rate of H2O2 was increased. The results of CV multi-cycle examination showed that LaNi0.8Fe0.2O3 had a good electrochemical stability.

关 键 词：催化剂 催化分解 双功能 电催化活性 H2O2 阴极极化 溶胶一凝胶法 氧还原 钙钛矿 扩散过程 

分 类 号：O646[理学—物理化学] O643[理学—化学]