(639e) The Role of Metal Nitrides in Selective Electrochemical Ammonia Synthesis

Electrochemical ammonia (NH₃) synthesis is an attractive alternative to the Haber-Bosch process. By removing the need for molecular hydrogen (H₂) as well as the high temperature and pressure requirements of the Haber-Bosch process, electrochemical NH­­₃ presents a step towards sustainable, decentralized agriculture.^1-2 However, electrochemical NH₃ synthesis is hindered by prohibitively low selectivity; H₂ production is kinetically favored over NH₃ production on every potential electrocatalyst currently known.³ In this study, we show how insights from electronic structure calculations of the energetics of the process, combined with mean-field microkinetic modeling, can be used to (1) understand the activity and selectivity challenges in electrochemical NH₃ synthesis, and (2) propose alternative strategies toward an economically viable process. In particular, we examine the role that metal nitrides will play in achieving these strategies by developing a theoretical understanding of their formation, activity, and stability. The theoretical understanding is further developed through collaborations with recent successful experimental efforts.