Perovskite ceramic oxide as an efficient electrocatalyst for nitrogen fixation.

The electrochemical conversion of N 2 to NH 3 is an interesting research topic as it provided an alternative and energy-saving method compared with the traditional way of NH 3 production. Although different materials have been proposed for N 2 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 LaFeO 3 to create oxygen vacancies, forming the Sr-doped LFO (La 0.5 Sr 0.5 FeO 3-δ) perovskite oxide. The La 0.5 Sr 0.5 FeO 3-δ ceramic oxide used as a catalyst achieves an NH 3 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 LaFeO 3 nanoparticles. The 15N isotope labeling method was employed to prove the La 0.5 Sr 0.5 FeO 3-δ catalyst had the function of converting N 2 into NH 3 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. Image 1 • Perovskite oxides were used for nitrogen reduction reaction. • The oxide with oxygen vacancy showed better nitrogen reduction reaction performance. • Isotope labeling experiment confirmed the conversion of nitrogen to ammonia. • The role of oxygen vacancy in reactions was revealed by first-principle calculations. [ABSTRACT FROM AUTHOR]