Heterojunction‐Type CeO ₂ /Ce‐NiCo ₂ O ₄ With Electron Cascade Transfer for Efficient Urea‐Assisted Hydrogen Production

ABSTRACT Developing efficient urea oxidation reaction (UOR) electrocatalysts is crucial for simultaneous urea‐rich wastewater purification and energy‐saving hydrogen production, yet it still remains a great challenge. Herein, based on the Hume‐ Rothery rule, one CeO 2 /Ce‐NiCo 2 O 4 UOR electrocatalyst integrating Ce single atoms and CeO 2 nanoparticles has been fabricated to synergistically trigger electron cascade transfer. As‐introduced Ce single atoms in Ce‐O‐Co symmetrical configuration can regulate the electron density of Co site, further enhancing the adsorption of reaction intermediates and lowering the energy barrier for the rate‐determining step of UOR. The strong built‐in electric field (BIEF) induces electron transfer from Ce‐NiCo 2 O 4 to CeO 2 , thus increasing the Ni oxidation state and promoting the formation of the γ‐NiOOH active phase for UOR. As‐prepared CeO 2 /Ce‐NiCo 2 O 4 exhibited enhanced UOR kinetic and thermodynamic, achieving 10 mA cm − 2 at 1.31 V with operational stability of 180 h. In an AEM electrolyzer, the CeO 2 /Ce‐NiCo 2 O 4 requires only 1.75 V to reach 500 mA cm − 2 , and continuously works well for over 60 h. Our work provides a facile strategy for constructing a highly efficient heterojunction‐type UOR electrocatalyst, and offers deep insights into electron transfer on boosting urea‐assisted hydrogen production.