Regulating the Electronic Configuration of Supported Iron Nanoparticles for Electrochemical Catalytic Nitrogen Fixation

Electrocatalytic nitrogen reduction reaction (eNRR) is a sustainable alternative to the traditional Haber–Bosch process due to its eco-friendly nature and capability of utilizing renewable energy. However, its low Faradic efficiency (FE), caused by the excessive adsorption and reduction of protons, has been regarded as the main challenge, which leads to low ammonia yield as well. Herein, a carbon-supported iron electrocatalyst is reported, which is fabricated by low-temperature (300 °C) potassium vapor reduction of FeF3-intercalated graphite fluoride, for efficient electrochemical nitrogen reduction. The strategy enables the unique formation of exposed Fe nanoparticles uniformly anchored on graphene and in situ doped with fluorine heteroatoms. These specific features can alter the electronic configuration of the Fe nanoparticles, leading to strong surface polarization that boosts nitrogen absorption capability for eNRR, resulting in high FE (41.6%) and ammonia yield rate (53.3 μg h-1 mg-1) simultaneously. First-principle calculation attributes this enhanced eNRR capability to more empty orbitals carried by the Fe atoms through the electron transfer with F dopant and substrate. As a versatile strategy for synthesizing various ultrafine and highly dispersed metal nanoparticles on the carbon support, this work might shed light on rational designing essential electrocatalysts with effective electronic structure manipulation.