Operando quantification of ammonia produced from computationally-derived transition metal nitride electro-catalysts

• Published in: Journal of catalysis Vol. 413; pp. 956 - 967
• Main Authors: Hanifpour, Fatemeh, Canales, Camila P., Fridriksson, Emil G., Sveinbjörnsson, Arnar, Tryggvason, Tryggvi K., Yang, Jian, Arthur, Connel, Jónsdóttir, Sigríður, Garden, Anna L., Ólafsson, Sveinn, Leósson, Kristján, Árnadóttir, Líney, Lewin, Erik, Abghoui, Younes, Ingason, Árni S., Magnus, Fridrik, Flosadóttir, Helga D., Skúlason, Egill
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2022
• Subjects: Ambient condition; Ammonia electrosynthesis; Aqueous electrolyte solution; Nitrogen reduction reaction; Transition metal nitride thin films; Ammonia electrosynthesis; Ambient condition; Transition metal nitride thin films; Nitrogen reduction reaction; Aqueous electrolyte solution
• ISSN: 0021-9517; 1090-2694; 1090-2694
• DOI: 10.1016/j.jcat.2022.07.030

[Display omitted] •Elucidating electrocatalytic behavior of ZrN, NbN, VN, and CrN towards N2 reduction.•Ammonia synthesis in a micro-reactor flow-cell following strict protocols.•Operando ammonia quantification without external intervention.•Conclusions based on multiple electrochemical techniques and surface analysis.•Detailed comparison of experimental and computational results. Electrochemical reduction of dinitrogen to ammonia is investigated in a micro-reactor flow-cell using thin films of VN, CrN, NbN and ZrN. Chronoamperometry loops are used for ammonia production analysis. Operando ammonia quantification is accomplished in a flow injection analyzer. Results show the effect of presence/absence of N2(g) within both the electrochemical characterization and ammonia production for ZrN. However, no ammonia is detected from studies on CrN. VN and NbN are inactivated upon reacting their N atoms of the surface top layer(s). Results obtained from ammonia measurements, electrochemical impedance spectroscopy analysis, surface stability checks, and surface characterization using X-ray reflectivity, reveal certain trends indicating catalytic behavior for ZrN. However, the concentration of produced ammonia is below the detection limit of the methods devised to analyze the samples from isotope labeling experiments. The onset of ammonia production on ZrN appears to be in close agreement with that predicted previously by computational studies.