Electrochemical synthesis of ammonia is a major challenge aimed at making production of ammonia sustainable. Currently ruthenium is the transition metal of choice for catalyzing the industrial Haber-Bosch process. However, electrochemical ammonia synthesis on ruthenium suffers from high overpotential and the competing hydrogen evolution reaction. Recently layered transition metals carbides and nitrides (MXenes) have been identified as a potential material class for ammonia synthesis. MXenes are particularly interesting owing to the high degree of tunability in surface chemistry due to the transition metal choice, interlayer distance, number of layers in the material, and surface termination. These choices affect the electron…