Flash calcination breaks the mechanical and catalytical behavior trade-off of alkaline oxygen evolution reaction electrodes

Abstract

The mechanical stability of the electrode structure is crucial for the stable operation of alkaline water electrolyzers (ALK) under industrial conditions. Calcination is a universal method to enhance the mechanical strength of electrodes. However, while ensuring reliable mechanical strength, the impact of calcination on electrode performance lacks assessment, which limits the catalytic potential of the electrodes. In this work, flash calcination is used to enhance the mechanical strength of electrodes prepared by electrodeposition, and the calcination boundary conditions necessary for obtaining reliable strength are determined. Furthermore, physical characterization and electrochemical tests reveal that calcination reduces the Oxygen Evolution Reaction (OER) activity by causing material agglomeration and reducing the number of hydroxyl adsorption sites on the surface. High-temperature short-time calcination by flash calcination could almost eliminate this negative effect to break the mechanical and catalytical behavior trade-off that the electrodes with or without calcination exhibited nearly the same initial voltage at 3000 A m⁻² in ALK. After running for 100 h, no increase in voltage was observed in the flash-calcined electrodes, whereas the uncalcined electrodes showed an increase of about 110 mV. This work establishes the structure-activity-stability relationships mediated by calcination for electrode structures and catalytic activity, providing guidance for the design of the next generation of high-activity, high-stability water electrolyzing electrodes.