電催化特性的影響
(昆明理工大學 材料科學與工程學院，昆明650093)
摘 要: 為了提高鈣鈦礦型La-Ca-Co-O的氧還原催化性能，采用檸檬酸輔助的溶膠−凝膠法制備添加AgNO3的La0.4Ca0.6CoO3粉體。采用XRD、SEM和EDAX分析手段研究凝膠在700 ℃焙燒后的產(chǎn)物，通過電位階躍技術(shù)測定不同Ag含量粉體的電化學有效表面積。通過線性掃描伏安法測定催化劑粉體催化氧還原反應的極化特性；通過Tafel技術(shù)測定其催化氧還原反應的交換電流密度。采用粉末壓片和直流電路測定催化劑的表觀電導率。結(jié)果表明：Ag+固溶入La0.4Ca0.6CoO3晶格導致晶格膨脹；添加AgNO3的粉體中還有單質(zhì)Ag顆粒析出。在La0.4Ca0.6CoO3中引入Ag+可顯著提高其對氧還原的電催化活性，在Ag含量為2%時，催化氧還原的交換電流密度達到最大值0.298 8 A/m2；而La0.4Ca0.6CoO3的表觀電導率隨著Ag含量增加而增大。
關(guān)鍵字: 鈣鈦礦型催化劑；氧還原；Ag含量；交換電流密度；電導率
perovskite-type La-Ca-Co-O to oxygen reduction
（Faculty of Materials Science and Engineering,
Kunming University of Science and Technology, Kunming 650093, China）
Abstract:In order to improve electrocatalytic property to oxygen reducing, the La0.4Ca0.6CoO3 powders with AgNO3 addition were prepared through citric acid sol-gel method. After being annealed at 700 ℃, the products were studied by XRD, SEM and EDAX. The electrochemical effective area of powders was determined through CA technology. The electrochemical polarization of powder for catalyzing oxygen reduction was investigated by LSV technology. The exchange current density was measured through Tafel technology. The apparent conductance of powder pellet was measured by DC method. The result shows that the silver ion dissolves into La0.4Ca0.6CoO3 lattice and brings on the latter expanding, the metal silver particles are affirmed in the microstructure. The electrocatalysis activity to oxygen reducing can be improved remarkably by introducing silver ion into La0.4Ca0.6CoO3 lattice. The maximum exchange current density, 0.298 8 A/m2, can be obtained when the silver content (mass fraction) is 2%. In addition, the apparent conductance increases with increasing the silver content.
Key words: perovskite catalyst; oxygen reduction; silver content; exchange current density; conductance
