Promoting electrochemical ammonia synthesis by synergized performances of Mo₂C-Mo₂N heterostructure

Hydrogen has become an indispensable aspect of sustainable energy resources due to depleting fossil fuels and increasing pollution. Since hydrogen storage and transport is a major hindrance to expanding its applicability, green ammonia produced by electrochemical method is sourced as an efficient hydrogen carrier. Several heterostructured electrocatalysts are designed to achieve significantly higher electrocatalytic nitrogen reduction (NRR) activity for electrochemical ammonia production. In this study, we controlled the nitrogen reduction performances of Mo₂C-Mo₂N heterostructure electrocatalyst prepared by a simple one pot synthesis method. The prepared Mo₂C-Mo₂N_0.92 heterostructure nanocomposites show clear phase formation for Mo₂C and Mo₂N_0.92, respectively. The prepared Mo₂C-Mo₂N_0.92 electrocatalysts deliver a maximum ammonia yield of about 9.6 μg h^-1 cm^-2 and a Faradaic efficiency (FE) of about 10.15%. The study reveals the improved nitrogen reduction performances of Mo₂C-Mo₂N_0.92 electrocatalysts due to the combined activity of the Mo₂C and Mo₂N_0.92 phases. In addition, the ammonia production from Mo₂C-Mo₂N_0.92 electrocatalysts is intended by the associative nitrogen reduction mechanism on Mo₂C phase and by Mars-van-Krevelen mechanism on Mo₂N_0.92 phase, respectively. This study suggests the importance of precisely tuning the electrocatalyst by heterostructure strategy to substantially achieve higher nitrogen reduction electrocatalytic activity.