Electrocatalytic NH 3 production from NO 3 − reduction is a promising alternative to traditional Haber-Bosch NH 3 synthesis. Although Nafion is commonly employed as a separator in two-compartment electrochemical cells and as a binder in catalyst inks, in this manuscript, we use Nafion as an overlayer on top of Cu electrodeposits to enhance NH 3 selectivity. Faradaic efficiencies for NH 3 and NO 2 − generation were evaluated as a function of electrodeposit morphology with and without the Nafion layer. These studies reveal that the combination of Cu (220) faces in the electrodeposits and activation of a NO intermediate by Nafion enables NH 3 production with a high Faradaic efficiency of (97.0 ± 0.3) %. This optimized architecture also exhibits the fastest rate of NH 3 production among the catalysts studied even after normalizing for its rough electrochemical active surface area. In addition to voltammetry, the electrocatalysts were characterized using a variety of techniques including atomic force microscopy, scanning electron microscopy, X-ray diffraction, and water contact angle measurements. Insights garnered about the parameters needed for selective NH 3 production will inform future research on nonprecious metal NO 3 − reduction catalysts.