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 LaNiO thin films, we demonstrate that strong tetragonal distortion of [NiO] 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 [NiO] 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 LaNiO suggests 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.

Tunable resistivity exponents in the metallic phase of epitaxial nickelates

“…ε xx is virtually zero across the 5-nm NNO film, showing a good in-plane lattice match between film and substrate, in agreement with the X-ray diffraction data. A thicker NNO film on LAO substrate also shows ε xx = 0 across most of the film, but it starts showing small regions with Ruddlesden-Popper (RP) faults, often reported in nickelates 52 , as seen in Fig. 4c, d.…”

Defect‐Rich Ni3FeN Nanocrystals Anchored on N‐Doped Graphene for Enhanced Electrocatalytic Oxygen Evolution

“…Similarly, Zhang and co‐workers discovered that ultrathin δ‐MnO 2 nanosheet arrays with abundant oxygen vacancies could give rise to half‐metallicity properties and strong H 2 O adsorption, leading them to exhibit superior OER and hydrogen evolution reaction activities in comparison with their counterparts and bulk δ‐MnO 2 . In addition, Chung and co‐workers found that the Ruddlesden–Popper 2D homologous faults can distort or elongate [NiO 6 ] octahedral in LaNiO 3 thin films and make them possess enhanced catalytic performance toward OER . These outstanding works demonstrate that engineering defects is a feasible and enticing avenue for developing advanced OER catalysts to use in water splitting or other technological fields.…”

Assemblage of Perovskite LaNiO3 Connected With In Situ Grown Nitrogen‐Doped Carbon Nanotubes as High‐Performance Electrocatalyst for Oxygen Evolution Reaction

“…Accordingly, various perovskite ABO 3 materials (e.g., LaNiO 3 , LaCoO 3 , etc.) have been synthesized and tested for OER in the last few years . However, large bulk particles are the typical existence form of perovskite oxides that lack a large portion of active sites on surface.…”

“…have been synthesized and tested for OER in the last few years. [14][15][16][17][18] However, large bulk particles are the typical existence form of perovskite oxides that lack a large portion of active sites on surface. As the electrochemical OER is a featured surface reaction, as a result, the bulk structure with a low specific surface area usually exhibits a low mass activity.…”