Ultrathin CuNi Nanosheets for CO₂ Reduction and O₂ Reduction Reaction in Fuel Cells

Developing efficient electrocatalysts applicable to CO 2 reduction reaction and fuel cells has drawn great attention for energy conservation and environmental protection. Molecular conversion of CO 2 to valuable products and fuel cells functioning with ultrahigh energy efficiencies is critical to remediate the global warming and energy crisis. Here, ultrathin hexagonal CuNi nanosheets are demonstrated to drive CO 2 reduction to C ≥ 2 products with a high Faradaic efficiency (80.5%) at −1.5 V vs RHE. Modulation of the d-band states, intermediate binding energy, and interatomic synergistic interaction between Ni and Cu are crucial for the enhancement of catalytic activity through intermediate binding control and boosting of charge transfer kinetics. In addition, a four-electron oxygen reduction reaction (ORR) process is validated for the ultrahigh performance in steady-state hydrogen–air fuel cells.