ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Microstructure-dependent magnetic property and oxygen evolution activity in LaMnO_3+δ electrocatalysts

Houming Shen, Chendong Shao, Qirui Wu, Yikai Sun, Sheikh Tamjidur Rahman, Geming Wang, and Peng Fan

Wuhan NARI Limited Liability Company, State Grid Electric Power Research Institute, Wuhan, China

E-mail: wanggemingwit@163.com

Received: 8 August 2025  Accepted: 4 June 2026

Abstract:

A series of perovskite-type LaMnO₃ (LMO) electrocatalysts (LMO-4, LMO-6, and LMO-8) with different oxygen contents (δ) has been successfully prepared by regulating the sintering temperature and time under nitrogen vs. air atmosphere sintered sample (LMO-0). We investigated the effects of microstructural features such as oxygen vacancies, adsorbed oxygen (O_ads), δ value, Mn³⁺/Mn⁴⁺ ratio, and Mn-O bond lengths on their magnetic performance and oxygen evolution reaction (OER) activity and its intrinsic correlation mechanism. The nitrogen induces crystal structure transition from tripartite phase (LMO-0) to orthorhombic phase and increases the adsorbed oxygen (O_ads) content with the variation of annealing conditions. LMO-0 with a high δ-value and high Mn⁴⁺ ratio exhibits a predominantly Mn³⁺-O-Mn⁴⁺ ferromagnetic double-exchange interaction. Among the samples, LMO-0 exhibits the optimal OER activity with the lowest apparent kinetic slope and charge transfer resistance, which is attributed to its highest Mn⁴⁺ ratio, oxygen vacancy content, and most significant electrochemically active area.

Keywords: LaMnO3+δ; OER; Oxygen vacancies; Magnetic phase transition; Double-exchange interaction

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-05183-9

Chemical Papers 80 (11) 13331–13346 (2026)