title: Formation of Two-Dimensional Homologous Faults and Oxygen Electrocatalytic Activities in a Perovskite Nickelate.
abstract: Atomic-scale direct probing of active sites and subsequent elucidation of the structure-activity relationship are important issues involving oxide-based electrocatalysts to achieve better electrochemical conversion efficiency. By generating Ruddlesden-Popper (RP) two-dimensional homologous faults via simple control of the cation nonstoichiometry in LaNiO3thin films, we demonstrate that strong tetragonal distortion of [NiO6] octahedra is induced by more than 20% elongation of Ni-O bonds in the faults. In addition to direct visualization of the elongation by scanning transmission electron microscopy, we identify that the distorted [NiO6] octahedra in the faults show considerably higher electrocatalytic activities than other surface sites during the electrochemical oxygen evolution reaction. This unequivocal evidence of the octahedral distortion and its impact on electrocatalysis in LaNiO3suggests that the formation of RP-type faults can provide an efficient way to control the octahedral geometry and thereby remarkably enhance the oxygen catalytic performance of perovskite oxides.
authors.affiliation: Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea.
authors.forename: Jumi
authors.initials: J
authors.lastname: Bak
authors.affiliation: Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea.
authors.forename: Hyung Bin
authors.initials: HB
authors.lastname: Bae
authors.affiliation: Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea.
authors.forename: Jaehoon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea.
authors.forename: Jihun
authors.identifier: 0000-0001-6465-6736
authors.initials: J
authors.lastname: Oh
authors.affiliation: Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea.
authors.forename: Sung-Yoon
authors.identifier: 0000-0002-2260-6201
authors.initials: SY
authors.lastname: Chung
keywords: Atomic-scale defects; TEM; electrocatalysis; oxygen octahedron; perovskite oxides