Electrochemical Analysis on Transition Metal Nitride Catalysts for Nitrogen Reduction Reaction

Abstract

A versatile and sustainable process for ammonia production is needed to ensure a sustainable future for the growing global population, both with regards to fertilizer production as well as energy carrier. Theoretical simulations of transition metal nitride catalysts have demonstrated the possibilityof a nitrogen reduction reaction catalysis cycle on four transition metal nitrides, CrN, VN, ZrN and NbN.[1,2] Reproducible and reliable research and development approaches in the direction of electrochemical reduction of nitrogen towards ammonia are therefore of importance. An operando ammonia quantification methodology for electrochemical catalysis studies has been developed in-house and recently published [3]. Allowing for automatic, quantitative detection of aqueouos ammonia at the ppb level, within minutes from the sample preparation. We have now analyzed all four theoretically proposed TMNs, as well as rutile Niobium oxynitride (NbON) of several stochiometries as thin films on a conductive electrode substrate in ambient environment and aqueouos electrochemical system [3,4].Electrochemical analysis and ammonia quantification suggest NbON of specific stochiometry and ZrN to be promising catalyst candidates, while lacking stability in the environment of choice in these studies.Literature:[1] Y. Abghoui, A.L. Garden, J.G. Howalt, T. Vegge and E. Skúlason, Electroreduction of N2 to ammonia at ambient conditions on mononitrides of Zr, Nb, Cr, and V: A DFT guide for experiments. ACS Catalysis, 2016.6(2): p. 635.[2] Y. Abghoui, A.L. Garden, V.F. Hlynsson, S. Björgvinsdóttir, H. Ólafsdóttir and E.Skúlason, Enabling electrochemical reduction of nitrogen to ammonia at ambient conditions through rational catalyst design. Physical Chemistry Chemical Physics,2015.17(7): p. 4909.[3] F. Hanifpour, C.P. Canales, E.G. Fridriksson, A. Sveinbjörnsson, T.K. Tryggvason,E. Lewin, . H.D. Flosadóttir, Investigation into the mechanism of electrochemical nitrogen reduction reaction to ammonia using niobium oxynitride thin-film catalysts. Electrochimica Acta, 2022.403: p. 139551.[4] F. Hanifpour, C.P. Canales, E.G. Friðriksson, A. Sveinbjörnsson, T. Tryggvason, Y.Abghoui, . E. Skúlason, Operando Quanitification of ammonia produced from computationally derived transition metal nitride electro catalysts. Journal of Catalysis, 2022. 413: p.956