标题：Elucidating d z 2 orbital selective catalytic activity in brownmillerite Ca2Mn2O5
作者：Lu, Yue ;Lu, Feng ;Yang, Zhi ;Wu, Jie ;Yu, Hongyun ;Xie, Xinjian ;Xu, Jianping ;Cheng, Fangyi ;Chen, Jun ;Xiong, Ka ;Liu, Hui ;Wang, Wei-Hua ;Zhao, Ji 更多 作者机构：[Lu, Yue ] Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing; 100124, China;[Wu, Jie ] Colle 更多
摘要：3d-orbital filling in transition metal oxide is crucial to govern the catalytic activity in oxygen evolution reduction, nevertheless, it is not fundamentally accessible why specific orbital occupation produces a highest catalytic performance. Here, we utilize brownmillerite Ca2Mn2O5to clarify the orbital selective catalytic behavior due to the crystal field splitting and on-site coulomb interactions. Within density functional theory plus dynamical mean field theory, Ca2Mn2O5shows a paramagnetic Mott insulating behavior at room temperature, consistent with optical adsorption spectra and magnetic susceptibility. As the center of the dz2 orbital locates in the lower Hubbard sub-band, the unit occupation on dz2 orbital provides a moderate bonding with external O∗ species to cause a high catalytic activity of Ca2Mn2O5with a square pyramid crystal field. Such concept of unit occupation of dz2 near Fermi level could be extended to other crystal fields for future design of oxide catalysts.
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