Vacancy engineering of BiFeO3 perovskite for low-barrier electrochemical nitrogen fixation

Because of its environmental and intrinsic benefits, the nitrogen reduction reaction (NRR) using electrocatalysts has garnered significant attention. Engineering on the surface is commonly utilized to improve electrocatalytic activity by introducing atomic defects. In this study, we have developed a successful strategy to promote nitrogen activation by introducing oxygen vacancies into BiFeO3 perovskite. BiFeO3 with oxygen vacancies (denoted as VO-BiFeO3) possesses a high NH3 yield rate (89.3 μg h-1 mgcat-1) and Faradaic efficiency (FE) (13.5%) at -0.40 V versus the reversible hydrogen electrode (RHE). According to density functional theory (DFT) calculations, the introduction of oxygen vacancies increases the binding capacity for nitrogen immobilization and reduces the energy barrier for the rate-determining step of NRR. Moreover, the analysis of the thermodynamic limiting potentials towards N2 reduction and H2 evolution demonstrates that VO-BiFeO3 has a higher selectivity for NRR than pristine BiFeO3.