Surface Atomic Decoration of a Manganite to a Modulable Oxygen Evolution Reaction.

Aiming at the fundamental understanding of oxygen evolution reaction (OER) in epitaxial perovskite transition metal oxide (TMO) thin films, we evaluate the surface decoration conditions, including lattice orientation and surface morphology, of La 2/3 Sr 1/3 MnO 3 (LSMO) related to its modulable OER performance. The LSMOs with orientations of (001), (110), and, (111) exhibit different OER activities owing to the discrepant surface density of Mn. Furthermore, tuning of the surface atomic terrace width of LSMO shows a more efficient path to modulate the OER performance by introducing a high-valence Mn state owing to the surface dangling bonds of LSMO. As the electrochemical process is dominated by the interface of the TMO surface and electrolyte, our investigation can approach the fundamental understanding of a perovskite-type TMO surface state and its OER performance while highlighting the role of the nonbulk electron state in a promising TMO electrocatalyst in abundant electrochemical processes.