The electrochemical conversion of N2 to NH3 is an interesting research topic as it provided an alternative and energy-saving method compared with the traditional way of NH3 production. Although different materials have been proposed for N2 reduction, the use of defects in oxides was only reported recently and the relevant working mechanism was not fully revealed. In this study, Sr was used as the dopant for LaFeO3 to create oxygen vacancies, forming the Sr-doped LFO (La0.5Sr0.5FeO3-δ) perovskite oxide. The La0.5Sr0.5FeO3-δ ceramic oxide used as a catalyst achieves an NH3 yield of 11.51 μgh−1 mg−1 and the desirable faradic efficiency (F.E.) of 0.54% at −0.6 V vs reversible hydrogen electrode (RHE), which surpassed that of LaFeO3 nanoparticles. The 15N isotope labeling method was employed to prove the La0.5Sr0.5FeO3-δ catalyst had the function of converting N2 into NH3 under the electrolysis condition. The first principle calculations were used to investigate the mechanism at the atomistic level, revealing that the free energy barriers changed significantly with the introduction of oxygen vacancies that accelerated the overall nitrogen reduction reaction (NRR) procedure.
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