Manipulating Surface Termination of Perovskite Manganate for Oxygen Activation
Xiyang Wang, Xinbo Li, Xuefeng Chu, Rui Cao, Jingyu Qian, Yingge Cong, Keke Huang, Jiaao Wang, Carl Redshaw, Ritimukta Sarangi, Guangshe Li, Shouhua Feng
Abstract
Abstract For ABO 3 perovskite oxides, one of the key issues limiting their utilization in heterogeneous catalysis is the dominant presence of catalytically inactive A‐site cations at the surface. The engineering of B‐site terminated perovskites is considered as an effective method to address this issue, especially when dealing with Mn/Co‐based perovskite catalysts. However, to date, such a strategy has not been fully successful and remains a major challenge in the field. Herein, a Mn‐terminated La 0.45 Sr 0.45 MnO 3 (B‐LSM) is successfully synthesized via a one‐pot hydrothermal method, in which low‐valence Mn ions partially occupy the A site to form the active Mn‐excess phase. Experimental results and theoretical calculations reveal that the presence of the surface Mn termination in B‐LSM optimizes the hybrid orbitals of Mn 3d‐O 2p and promotes the activation of surface lattice oxygen, where the pristine inert lattice O 2− is evolved into active and stable lattice O 2− x . Such structural optimization significantly reduces the activation energy barriers on going from O 2 − species to important intermediate O − species during O 2 activation. Moreover, this results in good stability and Pt‐like activity for the B‐LSM during CO oxidation. This work offers a new chemical route for the design of advanced perovskite‐type oxides possessing novel functions.