Novel confinement of Mn3O4 nanoparticles on two-dimensional carbide enabling high-performance electrochemical synthesis of ammonia under ambient conditions.

• Ultrafine Mn 3 O 4 nanoparticles are confined on MXene nanosheets as superior nitrogen reduction reaction electrocatalyst. • Elaborate 0/2D heteroarchitecture is fabricated through facile and versatile van der Waals assembly. • Evident synergy effect guarantees commendable activity, stability and durability of composite electrocatalyst. To date, the application of electrochemical nitrogen fixation into ammonia is severely hindered by the deficiency of high-performance electrocatalysts. In this paper, a facile approach is proposed for the preparation of MXene/Mn 3 O 4 composite catalyst, where Mn 3 O 4 nanoparticles are anchored tightly on the MXene nanosheets through van der Waals interactions. The obtained composite catalyst exhibiting powerful synergetic effect is able to provide abundant active sites for nitrogen reduction reaction. The introduction of MXene nanosheets dramatically improves the N 2 adsorption and charge transfer. When operated in 0.1 M Na 2 SO 4 aqueous media, MXene/Mn 3 O 4 achieves a proper Faradaic efficiency of 5.51% and superior NH 3 yield rate of 25.95 μg h−1 mg cat. −1 at −0.5 V under ambient conditions, outperforming either of individual components. Notably, this composite catalyst delivers superb stability, durability and selectivity as well. [ABSTRACT FROM AUTHOR]