High‐Entropy Alloy Catalysts with Hydrogen‐Rich Skin Layers for Enhanced Carbon Dioxide Electroreduction in Anion Exchange Membrane Cells

ABSTRACT The growing demand for efficient CO 2 conversion technologies in electrochemical systems has spurred the development of advanced catalysts and membrane designs. This study investigates the impact of hydrogen‐rich (H‐rich) skin layers, created through barbituric acid (BTA) modification, on the catalytic performance of Pt‐based and high‐entropy alloy (HEA) catalysts in anion exchange membrane (AEM) water electrolysis systems. The results show that BTA‐modified Pt and HEA catalysts significantly enhance CO 2 conversion efficiency, achieving a maximum current density of 395 mA cm −2 at 3 V and 40°C, alongside a CO 2 removal rate of 39.3%. The H‐rich skin layer on the catalysts enhances surface hydrophilicity, increasing water molecule affinity and facilitating higher surface concentrations of H 2 O and CO 2 , thereby accelerating crucial reaction steps in CO 2 reduction. Furthermore, these skin layers enhance ionic transport via hydrogen‐bonding interactions, optimizing both the oxygen evolution reaction at the anode and CO 2 reduction at the cathode. These findings suggest that the synergistic effects of H‐rich skin layers and HEA catalysts offer a promising strategy for improving the efficiency of electrochemical CO 2 conversion processes, providing valuable insights into the design of high‐performance AEM systems.