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 N-2 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 (V-O), 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 V-O 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 mu g 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 N-2 fixation.