Durable and Efficient Hollow Porous Oxide Spinel Microspheres for Oxygen Reduction
2017; Elsevier BV; Volume: 2; Issue: 2 Linguagem: Inglês
10.1016/j.joule.2017.11.016
ISSN2542-4785
AutoresHao Wang, Ruiping Liu, Yutao Li, Xujie Lü, Qi Wang, Shiqiang Zhao, Kunjie Yuan, Zhiming Cui, Xiang Li, Sen Xin, Ru Zhang, Ming Lei, Zhiqun Lin,
Tópico(s)Fuel Cells and Related Materials
ResumoSummary Transition metal oxide catalysts with high oxygen reduction activity and durability are highly desirable for use in fuel cells and metal-air batteries. Herein we report, for the first time, the oxygen reduction activity of hollow porous spinel AB 2 O 4 microspheres, where A = Zn 2+ and B = Mn 3+ and/or Co 3+ (i.e., ZnMn x Co 2−x O 4 ). Among them, ZnMnCoO 4 ( x = 1) microspheres exhibit the best oxygen reduction activity with a half-wave-potential only 50 mV lower than that of the Pt/C counterpart and an excellent durability in the alkaline solution. Importantly, the electronic transition of Co 3+ ions from low-spin state in commercial Co 3 O 4 catalyst to a mixed high-spin and low-spin state in ZnMnCoO 4 catalyst was found to weaken the Co 3+ -OH bond and facilitate the O 2− /OH − displacement. The density functional theory calculation substantiated that ZnMnCoO 4 displayed a more favorable binding energy with O 2 and oxygenated species, thereby enabling the fast reaction kinetics in the oxygen reduction reaction process.
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