Janus Electronic State Ni Enable High‐Level CO‐Tolerance in Fuel Cells Toward Crude‐Hydrogen Feeds

Maximizing the utilization efficiency of surface‐active atoms is essential for improving carbon monoxide (CO) tolerance of hydrogen oxidation reaction (HOR) catalysts. However, conventional active‐site regeneration strategies suffer from poor accessibility and low efficiency, hindering effective anion exchange membrane fuel cells (AEMFCs) operation under high‐CO‐concentration conditions. Here, we show a unique YbO x /Ni/C catalyst with Janus heterostructures that can significantly enhance the utilization efficiency of free active atoms by selectively adsorbing CO and promoting their directional elimination. Atomic resolution electron energy‐loss spectroscopy (EELS) analysis reveals that the gradient electronic states in Janus heterostructures are generated between the interfaces of YbO x /Ni and Ni/C. Density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations further reveal that electron‐rich Ni atoms near the Ni/YbO x interface serves as active sites for efficient removal of CO. In contrast, electron‐deficient Ni atoms situated near the Ni/C interface facilitate the efficient HOR. The AEMFC with this anode catalyst achieves an impressive peak power density (PPD) of 702.0 mW cm −2 in H 2 –O 2 , maintains a PPD of 304.3 mW cm −2 even in 1000 ppm CO/H 2 ‐CO 2 ‐free air and continues to operate under harsh conditions with 10000 ppm CO, first showing the possibility to use crude hydrogen in AEMFCs.