Nonstoichiometric Perovskite CaMnO3鈭捨?/sub> for Oxygen Electrocatalysis with High Activity

详细信息    查看全文

• 作者：Jing Du ; Tianran Zhang ; Fangyi Cheng ; Wangsheng Chu ; Ziyu Wu ; Jun Chen
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：September 2, 2014
• 年：2014
• 卷：53
• 期：17
• 页码：9106-9114
• 全文大小：627K
• ISSN：1520-510X

文摘

Perovskite oxides offer efficient and cheap electrocatalysts for both oxygen reduction reactions and oxygen evolution reactions (ORR/OER) in diverse oxygen-based electrochemical technologies. In this study, we report a facile strategy to enhance the electrocatalytic activity of CaMnO₃ by introducing oxygen defects. The nonstoichiometric CaMnO_{3鈭捨?/sub> (0 < 未 鈮?0.5) was prepared through thermal reduction of pristine perovskite microspheres and nanoparticles, which were synthesized from thermal-decomposition of carbonate precursors and the Pechini route, respectively. The as-prepared samples were analyzed by chemical titration, structural refinement, thermogravimetric analysis, and energy spectrometry. In 0.1 M KOH aqueous solution, the nonstoichiometric CaMnO3鈭捨?/sub> with 未 near 0.25 and an average Mn valence close to 3.5 exhibited the highest ORR activity (36.7 A g^鈥? at 0.70 V vs RHE, with onset potential of 0.96 V), which is comparable to that of benchmark Pt/C. Density functional theory (DFT) studies and electrical conductivity measurement revealed that the enhanced ORR kinetics is due to facilitated oxygen activation and improved electrical properties. Besides high activity, the nonstoichiometric perovskite oxides showed respectable catalytic stability. Furthermore, the moderate oxygen-defective CaMnO3鈭捨?/sub> (未 鈮?0.25) favored the OER because of the improved electrical conductivity. This study makes nonstoichiometric CaMnO3鈭捨?/sub> a promising active, inexpensive bifunctional catalytic material for reversible ORR and OER.}