Bamboo‐Like Carbon Nanotube‐Encapsulated Fe₂C Nanoparticles Activate Confined Fe₂O₃ Nanoclusters Via d‐p‐d Orbital Coupling for Alkaline Oxygen Evolution Reaction

The efficient anion exchange membrane water electrolysis is challenging with low cell voltage and long-term stability at large current density, due to the unstable anodic oxygen evolution reaction (OER). Fe-based electrocatalysts are potential candidates for the anodic OER. In Fe-based materials, iron oxides always show better stability in alkaline solution but lower OER activity. However, the catalysts in previous study are difficult to continuously and effectively activate iron oxides supported on carbon during electrocatalysis. Herein, a new class of electrocatalyst: bamboo-like carbon nanotubes (B-CNT)-encapsulated Fe₂C nanoparticles (NPs) supported Fe₂O₃ nanoclusters (NCs), named Fe₂O₃/B-CNT@Fe₂C is reported. Theoretical calculations and experimental results reveal that B-CNT-encapsulate Fe₂C NPs activate Fe₂O₃ NCs by the d-p-d orbital coupling, thereby weakening the adsorption of OOH* intermediate during OER process. The electrolyzer based on the electrocatalyst requires only 1.48 V to reach 1.0 A cm^-2 and shows a long-term stability at 1.0 A cm^-2 for 1600 h, comparable to the best-reported values for the anion exchange membrane water electrolyzer (AEMWE).