Electrochemical Nitric Oxide Reduction on Metal Surfaces

Abstract

Electrocatalytic denitrification is a promising technology for removing NO_x species (NO₃^- , NO₂^- and NO). For NO_x electroreduction (NO_x RR), there is a desire for understanding the catalytic parameters that control the product distribution. Here, we elucidate selectivity and activity of catalyst for NO_x RR. At low potential we classify metals by the binding of *NO versus *H. Analogous to classifying CO₂ reduction by *CO vs. *H, Cu is able to bind *NO while not binding *H giving rise to a selective NH₃ formation. Besides being selective, Cu is active for the reaction found by an activity-volcano. For metals that does not bind NO the reaction stops at NO, similar to CO₂ -to-CO. At potential above 0.3 V vs. RHE, we speculate a low barrier for N coupling with NO causing N₂ O formation. The work provides a clear strategy for selectivity and aims to inspire future research on NO_x RR.

Keywords: DFT; NOx removal; ammonia synthesis; electrocatalysis; metal surfaces.