We propose selectivity towards ammonium is greater on surfaces favoring dissociative nitric oxide adsorption and subsequent N * adatom hydrogenation by H * (Figure and). Here we discuss the relationship between nitric oxide adsorption and dissociation energies and TM electronic structure by DFT. We limit our discussion to elements in metallic state under the NO3RR conditions considered here, with consideration of Ti (uncertain surface oxidation state) in the SI (Supplementary Table ).