Layer-by-Layer Electrode Design Integrating a Macroporous Carbon-Nanotube Skeleton for an Anion-Exchange Membrane Water Electrolyzer

Abstract Three-dimensional porous electrodes (anodes and cathodes) using only non-noble-metal electrocatalysts are important for enhancing the performance of anion-exchange membrane water electrolysis (AEMWE), contributing to reduced green-hydrogen production costs. This study designed a layer-by-layer (LbL) electrode with a macroporous carbon nanotube (CNT) skeleton for an anode and cathode by modifying the fabrication to enable a uniform distribution of catalyst nanoparticles throughout the electrode. The LbL anode and cathode, fabricated by loading NiFe and NiFeOx as oxygen (OER) and hydrogen (HER) evolution reaction catalysts, respectively, onto the CNT skeleton, resulted in macroporous electrodes with square pores. Compared to conventional electrodes with densely loaded catalysts, the LbL electrodes exhibited enhanced OER activity and similar HER activity and stability. The practical performance of AEMWE employing LbL electrodes exceeded those of CNT-based electrodes without LbL processing, and conventional electrodes. Moreover, durability data showed that the AEMWE integrating LbL electrodes maintained stable performance without significant degradation.