Electrochemical Nitrogen Reduction Kinetics on a Copper Sulfide Catalyst for NH₃Synthesis at Low Temperature and Atmospheric Pressure

Abstract

We studied the electrochemical synthesis of NH3 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 NH3 production yield of 16 μg h–1 cm–2 at −0.4 V RHE, while it decomposes to CuO. The rapid degradation of the catalyst hinders the precise investigation of the NH3 production activity in longer time measurements. Herein, the electrochemical NH3 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 NH3 production activities among the reported metal sulfide electrochemical NRR catalysts is obtained, which is 42 μg h–1 cm–2 at −0.6 VRHE.

Synergistic Multisites Fe2Mo6S8 Electrocatalysts for Ambient Nitrogen Conversion to Ammonia

“…The surface density of Fe sites was estimated as 1.64 × 10 14 Fe sites cm –2 from lattice parameters extracted from Rietveld refinement results (2 Fe sites per Mo 6 S 8 cluster). On the basis of these assumptions, the TOF was estimated as 0.23 s –1 , and this is substantially higher than that of the existing catalysts, including Fe single atom, , Fe-CuS, metal VN x , Bi, and transition metal dichalcogenide, ,, further verifying the intrinsic activities of the Fe–Mo 6 S 8 active site motifs.…”

Fe‐based catalysts for nitrogen reduction toward ammonia electrosynthesis under ambient conditions

“…Some transition metals (Co, 93‐96 Cu, 97 Ti, 99,100 and V 101,102 ) and rare earth metals (Ce 103 ) also have common cofactors for Fe, enhancing the electrocatalytic NRR performance. We summarize a series of Fe‐M (Co, Cu, Ti, V, and Ce) materials in this section to study the activity and stability of Fe‐M catalysts.…”

Defect and interface engineering in metal sulfide catalysts for the electrocatalytic nitrogen reduction reaction: a review

“…XRD and XPS indicated that CuS transformed into CuO. 94 Therefore, the degradation reactions of the metal sulfides should also be considered when investigating the NRR activity of electrocatalysts.…”