From half-cells to full-cells: across-scale comparative evaluation of lanthanum-based perovskites as high-performance anode materials for the oxygen evolution reaction

The widespread reliance on evaluating electrocatalysts in electrochemical half-cells presents limitations that hinder a faster transition from academia to industry and can lead to premature exclusion of promising materials. To address these challenges, it is crucial to implement materials testing in application-relevant setups such as zero-gap full-cells. This transition can be achieved through implementing coherent workflows combining rapid evaluation of as-synthesized materials, electrode evaluation at different scales, and post-mortem analysis. This work presents a comparative study of three spray-flame synthesized lanthanum-based perovskite materials (LaMnO3, LaFeO3, and LaCoO3) for the oxygen evolution reaction under alkaline conditions, highlighting different behavior across scales. The research demonstrates how the interplay of materials properties, electrode engineering, and metal-support interactions influences performance under mild and harsh electrochemical conditions. Electrochemical half-cell testing consistently identifies LaFeO3 as the best oxygen evolution reaction catalyst across various configurations. This unforeseen behavior necessitates further investigation under application-relevant conditions. Full-cell testing at 500 mA cm-2 corroborates the trends observed in electrochemical half-cell testing, with LaFeO3 and LaMnO3 exhibiting comparable performance to LaCoO3 after prolonged operation. Furthermore, a degradation study under 1000 mA cm-2 highlights their potential for continued catalyst development. Advanced post-mortem techniques provide deeper insight into catalytic activity and structural changes, linking performance evolution to catalyst-substrate interactions and material-dependent surface changes under oxidative polarization. By bridging fundamental studies to application-relevant testing, this research provides knowledge and methods for accelerated material and electrode development.