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 H₂-O₂, maintains a PPD of 304.3 mW cm^-2 even in 1000 ppm CO/H₂-CO₂-free air and continues to operate under harsh conditions with 10000 ppm CO, first showing the possibility to use crude hydrogen in AEMFCs.