Electrochemical Nitric Oxide Reduction on Metal Surfaces

Electrocatalytic denitrification is a promising technology for removing NOx species
(NO3− , NO2− and NO). For NOx electroreduction (NOxRR), there is a desire for
understanding the catalytic parameters that control the product distribution. Here,
we elucidate selectivity and activity of catalyst for NOxRR. At low potential we clas-
sify 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 selec-
tive 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 N2O formation. The work provide a clear strategy for selectivity and
aims to inspire future research on NOxRR.