FE are expected to be more pronounced for lower nitrate concentrations typical of e.g. groundwater (~1.5 mM). Figure . (a) NO3RR FE against work function and (b) selectivity towards ammonium against Ed vs EF for denoted TM foils measured by 85% iR-corrected chronoamperometry to 0.2 e -/NO3 -at select potentials (-0.4, -0.5, and -0.6 VRHE; denoted), except for Ti where -0.7 VRHE is used to obtain sufficient current. Lines to guide the eye. Ti is excluded from (a) due to uncertainties in work function and surface termination (e.g. oxidation state or presence of hydrides), but is included in Supplementary Figure ). ◊ † Data for work function adapted from Ref. and Ed vs EF from Ref. , with values (a,b) for Ni0.68Cu0.32 interpolated from literature values for Ni and Cu.