Tetra Pyridinic Coordinated Molecular Catalysts for Electrochemical Nitrate Reduction

The electrochemical reduction of nitrate is an emerging field offering a sustainable pathway toward both nitrate waste mitigation and ammonia production. To ensure the advancement of electrochemical nitrate reduction technologies, a fundamental understanding of the reaction mechanisms required to convert nitrate selectively to ammonia is critical. This insight can be provided through extensive testing of structurally well-defined catalysts to understand the electrochemical performance of various active site structures and their coordinating environments. In this work, we synthesized and tested molecular catalysts with well-defined structures containing tetra pyridinic coordinated metal sites for the electrochemical nitrate reduction reaction. The selectivity, stability, and activity of the catalysts, containing various first row transition metal centers, for the nitrate reduction reaction have been evaluated. The catalysts dispersed onto multi–walled carbon nanotubes displayed high selectivity toward ammonia production of up to 98.6 % faradic efficiency at an electrode potential of -0.5 V vs RHE. The development of such catalysts is critical for understanding the role of tetra pyridinic coordination sites needed to guide the design of future metal–nitrogen coordinated catalysts. In this presentation, we will discuss the characterization and electrochemical performance of the synthesized tetra pyridinic molecular catalysts to understand the role of coordination site structure for the electrochemical nitrate reduction reaction.