B-site錳摻雜鑭鍶層狀鈣鈦礦氧化物觸媒於1 M NaOH水溶液中之氧化還原催化特性研究

Catalytic Activity of LaSr3Fe3-xMnxO10 for Oxygen Reduction Reaction in 1 M Sodium Hydroxide Solution

本研究利用Pechini法製備B-site錳摻雜鑭鍶鐵層狀鈣鈦礦氧化物觸媒，以電化學旋轉電極測試分析探討B-site錳摻雜量對鑭鍶鐵層狀鈣鈦礦氧化物觸媒於1 M NaOH鹼性溶液中與氧還原（Oxygen reduction reactions, ORR）活性之間的關係。結果顯示Pechini法製備鑭鍶鐵層狀鈣鈦礦氧化物於1100℃退火時間48小時後為完整結晶，無明顯雜項。B-site錳摻雜量x > 0.5時會產生四氧化三錳結晶雜相。經由旋轉電極結果顯示，隨著B-site錳摻雜量增加，氧還原之催化活性亦提升，直至過量錳摻雜導致雜相產生而降低活性。配合Koutecky-Levich equation計算B-site錳摻雜有助於催化4個電子轉移的氧還原反應路徑進而提升氧催化活性。

Catalyst activity of LaSr3Fe3-xMnxO10 prepared by Pechini method for oxygen reduction reaction (ORR) in 1 M NaOH electrolyte was investigated in this work. The dependence of the catalytic activity was explored by means of rotating disk electrode (RDE). Result from X-ray diffraction revealed that LaSr3Fe3O10 powders synthesized under annealing temperature 1100 ℃ for 24 hours were pure polycrystalline phase. However, LaSr3Fe3-xMnxO10 showed a second phase with doping amount x > 0.5. Analysis of RDE indicated that the catalytic activity of LaSr3Fe3- xMnxO10 increased with an increasing x until the appearance of second phase. The electron transfer number was estimated by fitting the RDE data into Koutecky-Levich equation. It was found that Mn substitution with B-site cations make a contribution to catalyze 4-electons transfer reaction, which improved ORR activity.