Optimizing Fe-3d Electron Delocalization by Asymmetric Fe-Cu Diatomic Configurations for Efficient Anion Exchange Membrane Fuel Cells

Precisely designing asymmetric diatomic configurations and studying their electronic regulation effect for improving the oxygen reduction reaction (ORR) performance are important for anion exchange membrane fuel cells (AEMFCs). Here, a Fe, Cu co-doped 2D crystalline IISERP-MOF27 nanosheet derived FeN3O-CuN4 diatomic site nanocatalyst (named as FeCu-NC) is synthesized for the cathodes of AEMFCs. Thanks to the optimal electronic structure of FeN3O-CuN4 in the FeCu-NC catalyst, it shows enhanced half-wave potential (0.910 V), turnover frequency (0.165e s-1 site-1), and decreased activation energy (19.96 kJ mol-1) in KOH. The FeCu-NC-based AEMFC achieves extremely high kinetic current (0.138 A cm-2 at 0.9 V) and rated power density (1.09 W cm-2), surpassing the best-reported transition metal-based cathodes. Density functional theory calculations further demonstrate that the Cu-N4 can break the localization of Fe-3d orbitals, accelerate the electron transport, and optimize the OH adsorption, thus facilitating the ORR process. A FeN3O-CuN4 diatomic site nanocatalyst (FeCu-NC) is derived from a Fe, Cu co-doped IISERP-MOF27 nanosheet material. The introduction of CuN4 site directly bonding with FeN3O center can induce asymmetric electron distribution with moderate adsorption/desorption behavior with oxygen intermediates. The optimized FeCu-NC catalyst exhibits excellent electrocatalytic oxygen reduction reaction activity and extraordinary anion exchange membrane fuel cell performance.image