Electrocatalytic synthesis of ammonia by surface proton hoppingElectronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00840f

Highly efficient ammonia synthesis at a low temperature is desirable for future energy and material sources. We accomplished efficient electrocatalytic low-temperature ammonia synthesis with the highest yield ever reported. The maximum ammonia synthesis rate was 30 099 μmol g cat −1 h −1 over a 9.9 wt% Cs/5.0 wt% Ru/SrZrO 3 catalyst, which is a very high rate. Proton hopping on the surface of the heterogeneous catalyst played an important role in the reaction, revealed by in situ IR measurements. Hopping protons activate N 2 even at low temperatures, and they moderate the harsh reaction condition requirements. Application of an electric field to the catalyst resulted in a drastic decrease in the apparent activation energy from 121 kJ mol −1 to 37 kJ mol −1 . N 2 dissociative adsorption is markedly promoted by the application of the electric field, as evidenced by DFT calculations. The process described herein opens the door for small-scale, on-demand ammonia synthesis. We accomplished efficient electrocatalytic low-temperature ammonia synthesis with the highest yield reported to date.