Electrochemical Nitrogen Reduction to Ammonia by Mo2N: Catalysis or Decomposition?

Electrocatalytic synthesis of ammonia from nitrogen (N₂) representsa highly attractive approach to produce ammonia under more energy efficient and CO₂-free conditions in comparison the well-known Haber-Bosch process. electrocatalytic N2 fixation has been under intensive exploration over last few years and has become a hot topic in catalysis. A number of heterogeneous electrocatalysts have been reported with various claimed performance for NRR recently. However, the research practice in this emerging field has been problematic as demonstrated in the submitted work.

Metal nitrides have been studied both theoretically and experimentally indicating their potential capability of electrocatalytic N₂reduction. However, the nitrogen contained nature and chemical stability problem of the nitride materials could bring in ambiguous results. In the submitted manuscript, it is revealed that Mo₂N could undergo fast chemical decomposition in aqueous electrolytes to generate ammonium (NH₄⁺) and showed no catalytic activity for NRR. The present results call urgent attention to carefully evaluate the catalytic nature of nitrogen reduction reaction (NRR) by nitrogen containing materials.In addition, we also highlight apparent pitfalls to avoid in determining catalytic NNR.