Laser Preset of MnO_x Layer on High-Entropy Alloy Surface for Ampere-Level Ultra-Stable OER Performance

Electrocatalytic water splitting offers an efficient pathway for producing renewable hydrogen, which is considered a key strategy toward global carbon neutrality. Yet, under harsh industrial operating conditions, the catalyst inevitably undergoes dynamic structural reconstruction, oxidative dissolution of active sites, and mechanical detachment during high-potential anodic oxygen evolution reaction (OER), severely limiting their activity and stability. Here, we present an MnO_x (composed of Mn₃O₄ and Mn₂O₃) layer on the FeCoNiCrMn high-entropy alloy (HEA) surface (denoted as HEA-ML) via laser powder bed fusion (LPBF) process and reveal that the MnO_x layer suppresses multimetal dissolution in HEA and mitigates excessive surface reconstruction under OER conditions. Furthermore, the MnO_x layer featuring a porous and rough surface enhances water adsorption and bubble diffusion, thereby accelerating interfacial mass transfer and OER kinetics. These outstanding features endow the catalyst to exhibit both excellent activity (227 ± 2 mV at 10 mA cm^-2) and industrial-grade ultra-stable OER performance (operating stably for 1500 h at 1.0 A cm^-2). Our research findings provide new insights into the structure-activity-stability relationship of HEA electrocatalysts and demonstrate a novel approach for designing industrially viable OER catalysts with high activity and ultra-stability.