Electrochemical Nitrogen Reduction Kinetics on a Copper Sulfide Catalyst for NH Synthesis at Low Temperature and Atmospheric Pressure.

We studied the electrochemical synthesis of NH on Fe-CuS/C catalysts in an alkaline aqueous solution under ambient conditions. The metal chalcogenide catalyst is active in the nitrogen reduction reaction (NRR) for approximately 45 min with an NH production yield of 16 μg h cm at -0.4 , while it decomposes to CuO. The rapid degradation of the catalyst hinders the precise investigation of the NH production activity in longer time measurements. Herein, the electrochemical NH production rate is enhanced with increased overpotentials when the degradation effect is mitigated in the measurement, which was difficult to observe in the NRR reports. In the Tafel analysis, the exchange current density, heterogeneous rate constant, and transfer coefficient of the Fe-CuS/C catalyst on the NRR were estimated. When the electrode degradation is mitigated, one of the best NH production activities among the reported metal sulfide electrochemical NRR catalysts is obtained, which is 42 μg h cm at -0.6 V.