Fe-doping induced morphological changes, oxygen vacancies and Ce3+–Ce3+ pairs in CeO2 for promoting electrocatalytic nitrogen fixation

Developing active and robust catalysts for the electrocatalytic N2 reduction reaction (NRR) represents a promising strategy for ambient NH3 production but remains challenging. Herein, CeO2 was modulated by Fe-doping for the NRR in neutral media. Fe-doping was found to induce the morphological change of CeO2 from crystalline nanoparticles to partial-amorphous nanosheets which contained abundant oxygen vacancies (VO), resulting in more exposed active sites and accelerated electron transport. Density functional theory (DFT) calculations further revealed that the coexistence of the Fe dopant and its adjacent VO enabled the creation of Ce3+–Ce3+ pairs which served as the most active centers for effectively catalyzing the NRR and suppressing the hydrogen evolution reaction. These Fe-doping induced synergistic effects led to a significantly enhanced NRR performance of Fe-CeO2 with an NH3 yield of 26.2 μg h−1 mg−1 (−0.5 V) and a faradaic efficiency of 14.7% (−0.4 V). Therefore, this metal-doping induced multifunctionality will open up new opportunities to design powerful NRR catalysts for N2 fixation.