Perovskite ceramic oxide as an efficient electrocatalyst for nitrogen fixation

The electrochemical conversion of N-2 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 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 LaFeO3 to create oxygen vacancies, forming the Sr-doped LFO (La0.5Sr0.5FeO3-delta) perovskite oxide. The La(0.5)Sr(0.5)FeO(3-delta-)ceramic oxide used as a catalyst achieves an NH3 yield of 11.51 mu gh(-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 N-15 isotope labeling method was employed to prove the La0.5Sr0.5FeO3-delta catalyst had the function of converting N-2 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. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study utilized Sr as a dopant for LaFeO3 to create oxygen vacancies, forming Sr-doped LFO perovskite oxide, which exhibited superior NH3 yield and faradic efficiency as a catalyst compared to other materials. The N-15 isotope labeling method confirmed the catalyst's ability to convert N-2 into NH3 under electrolysis conditions. First principle calculations revealed that the introduction of oxygen vacancies significantly accelerated the overall nitrogen reduction reaction process.