Strategies toward Selective Electrochemical Ammonia Synthesis

The active and selective electroreduction of atmospheric nitrogen (N2) to ammonia (NH3) using energy from solar or wind sources at the point of use would enable a sustainable alternative to the Haber–Bosch process for fertilizer production. While the process is thermodynamically possible, experimental attempts thus far have required large overpotentials and have produced primarily hydrogen (H2). In this Perspective, 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 develop the theoretical understanding for two promising actionable avenues that are gaining interest in the experimental literature, (1) circumventing the scaling relations between adsorbed surface intermediates and (2) using nonaqueous electrolytes to suppress the competing hydrogen evolution reaction.