Quantitative Operando Detection of Electro Synthesized Ammonia Using Mass Spectrometry. Issue 6 (23rd March 2022)

• Record Type: Journal Article
• Authors: Krempl, Kevin; Hochfilzer, Degenhart; Cavalca, Filippo; Saccoccio, Mattia; Kibsgaard, Jakob; Vesborg, Peter C. K.; Chorkendorff, Ib
• Is Part Of: ChemElectroChem. Volume 9:Issue 6(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-23
• Subjects: ammonia detection -- nitrogen reduction -- lithium-mediated ammonia synthesis -- nitrate reduction -- mass spectrometry; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.202101713
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: In this work the successful operando detection of synthesized ammonia from nitrogen reduction in non‐aqueous electrolytes with an electron‐ionization mass spectrometer was reported. Using selective ionization at 22 eV together with a highly sensitive micro‐chip‐based electrochemistry mass spectrometry set‐up, quantitative detection of produced ammonia down to few pmol s −1 in non‐aqueous as well as aqueous electrolytes was demonstrated. The well‐defined electrochemical and mass transport environment of the thin‐layer electrochemical cell allowed for fundamental studies of the nitrogen reduction process, which was shown to produce ammonia at faradaic efficiencies of 49±3 % at ambient pressure. Moreover, through the operando capabilities of the developed method, it was shown that ammonia production proceeded even after lithium electroplating had been terminated This potentially explained why higher faradaic efficiencies of lithium mediated ammonia synthesis were observed under dynamic cycling conditions. Two possible mechanisms for this behavior were proposed and an outlook towards future research in operando studies of lithium mediated ammonia synthesis was given. Abstract : Selective ionization : of ammonia at 22 eV in a conventional electron ionization mass spectrometer enabled operando detection of electrosynthesized ammonia. This was demonstrated by successful nitrogen reduction to ammonia in a non‐aqueous electrolyte at an average faradaic efficiency of 49 %. Moreover, the dynamic behavior of the lithium mediated nitrogen reduction reaction was measured under operando conditions for the first time.