Lanthanum-Nickel-Based Mixed-Oxide-Coated Nickel Electrodes for the OER Electrocatalysis

Abstract

The anodic oxygen evolution reaction (OER) remains a bottleneck for electrocatalytic water splitting due to its sluggish kinetics and, thus, high overpotentials. This limits water electrolysis as a key technology for the generation of hydrogen as a sustainable alternative to fossil fuels. For alkaline water splitting, perovskite phases (ABO₃) with earth-abundant first-row transition-metals have emerged as a promising material class for OER electrocatalysts. Among these, LaNiO₃ has been found to exhibit high intrinsic OER activity. To increase catalyst utilization, a high surface area of the catalyst is desirable and can be achieved by impregnation of porous templates. In this work, La–Ni-based oxides were prepared via impregnation of activated carbon and subsequent heating, combining precursor calcination and template removal into one step. The phase structure of the samples is analyzed via powder X-ray diffractometry, and the morphology is determined by scanning electron microscopy. The synergistic effect of B-site mixing iron as well as A-site mixing strontium into LaNiO₃ is studied and found to increase its OER activity, confirming the activity-enhancing effect of Fe in Ni-based OER electrocatalysts. To allow for facile technical application of the catalysts, the electrodes are prepared by coating a perovskite ink onto Ni-metal as industrially relevant substrates, followed by calcination.