Authors: Yong Beom Kim | WooChul Jung | Jeong Jin Lee | Jeongah Lee
Source: ECS Meeting Abstracts (article, 2025-07-11)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Understanding of Strain Induced Dynamic Surface Reconstruction of LaNiO<sub>3</sub> for Oxygen Evolution Reaction The oxygen evolution reaction (OER) is a critical process in numerous electrochemical energy conversion and storage systems, including hydrogen production via water electrolysis, fuel generation through CO 2 or N 2 reduction, and metal−air batteries all vital technologies for a sustainable circular economy. However, the slow kinetics of OER at the anode remains a major bottleneck, limiting power efficiency and hindering the widespread adoption of these technologies. Various classes of non-precious transition metal oxides have demonstrated promising OER performance, but enhancing electrocatalyst efficiency requires a deeper understanding of the structure–property–performance relationship. To address this, several OER activity descriptors, such as the electron occupancy of the e g orbital, Δ GO *−ΔG HO *, and oxygen 2p band center, have been proposed. However, under actual operating conditions, OER catalysts are exposed to alkaline electrolytes under a variety of applied potentials. For example, during water splitting under oxidation potential, during load fluctuations caused by the intermittency of renewable energy sources, or during repeated OER and ORR cycles at the cathode of metal–air batteries, catalysts experience a broad range of potentials. Meanwhile, the applied potential, coupled with the intrinsic properties of the catalyst, plays a pivotal role in determining its stability and driving surface phase evolution in alkaline electrolytes. Consequently, the catalytically active surface under operating conditions often exhibits characteristics that differ significantly from those of the pristine catalyst. This complexity makes understanding the structural evolution of catalysts and uncovering the traits of active surfaces a formidable challenge. Even more demanding is the task of fine-tuning dynamic surface evolution and precisely controlling the in situ formation of active species during catalysis. In this study, we investigate epitaxially grown LaNiO 3 thin films as a model perovskite oxide electrode material for the OER in purified alkaline electrolyte. We demonstrate that the magnitude of the reduction potential during potential cycling plays a significant role in determining the degree of surface reconstruction of LaNiO 3 in alkaline electrolytes. The reduction of lattice nickel in LaNiO 3 leads to the formation of redox active NiO x /Ni(OH) 2 on the catalyst surface which is further oxidized to (oxy)hydroxide in OER operating conditions. In contrast, the oxidation potential has minimal impact on the extent of surface reconstruction, acting instead as a threshold. This finding challenges the traditional belief that enhanced activation of lattice oxygen at higher oxidizing potentials during the OER accelerates surface reconstruction in LaNiO 3 . Furthermore, the electronic structure of LaNiO 3 is modulated by lattice strain, which alters the reduction behavior of Ni and modifies the degree of surface reconstruction. Moreover, electrolyte Fe impurities forms dynamically stable active sites on the surface of nickel (oxy)hydroxide, establishing a correlation between the degree of surface reconstruction and catalyst activity. Lanio ; Strain (injury) ; Oxygen ; Materials science ; Chemistry ; Biology ; Optoelectronics Magnetic and transport properties of perovskites and related materials ; Advancements in Solid Oxide Fuel Cells ; Catalytic Processes in Materials Science