Introducing oxygen vacancies in a bi-metal oxide nanosphere for promoting electrocatalytic nitrogen reduction

The sluggish breakage of the N-N triple bond, as well as the existence of a competing hydrogen evolution reaction (HER), restricts the nitrogen reduction reaction process. Modification of the catalyst surface to boost N 2 adsorption and activation is essential for nitrogen fixation. Herein, we introduced surface oxygen vacancies in bimetal oxide NiMnO 3 by pyrolysis at 450 °C (450-NiMnO 3 ) to achieve remarkable NRR activity. The NiMnO 3 3D nanosphere with a rough surface could increase catalytically active metal sites and introduce oxygen vacancies that are able to enhance N 2 adsorption and further improve the reaction rate. Benefiting from the introduced oxygen vacancies in NiMnO 3 , 450-NiMnO 3 showed excellent performance for nitrogen reduction to ammonia with a high NH 3 yield of 31.44 μg h −1 mg cat −1 (at −0.3 V vs. RHE) and a splendid FE of 14.5% (at −0.1 V vs. RHE) in 0.1 M KOH. 450-NiMnO 3 also shows high long-term electrochemical stability with excellent selectivity for NH 3 formation. 15 N isotope labeling experiments further verify that the source of produced ammonia is derived from 450-NiMnO 3 . The present study opens new avenues for the rational construction of efficient electrocatalysts for the synthesis of ammonia from nitrogen. In this work, oxygen vacancy abundant NiMnO 3 achieves a superior NH 3 yield of 31.44 μg h −1 mg cat −1 at −0.3 V vs. RHE and a faradaic efficiency of 14.5% at −0.1 V vs. RHE.