Molybdenum Carbide Nanodots Enable Efficient Electrocatalytic Nitrogen Fixation under Ambient Conditions. 
Electrocatalytic nitrogen fixation is considered a promising approach to achieve NH3 production.  However, due to the chemical inertness of nitrogen, it is necessary to develop efficient catalysts to facilitate the process of nitrogen reduction.  Here, molybdenum carbide nanodots embedded in ultrathin carbon nanosheets (Mo2 C/C) are developed to serve as a catalyst candidate for highly efficient and robust N2 fixation through an electrocatalytic nitrogen reduction reaction (NRR).  The as-synthesized Mo2 C/C nanosheets show excellent catalytic performance with a high NH3 yield rate (11.3 µg h-1 mg-1 Mo2C ) and Faradic efficiency (7.8%) for NRR under ambient conditions.  More importantly, the isotopic experiments using 15 N2 as a nitrogen source confirm that the synthesized ammonia is derived from the direct supply of nitrogen.  This result also demonstrates the possibility of high-efficiency nitrogen reduction even though accompanied with vigorous hydrogen evolution.