We remark here that the initial adsorption of nitrate is poorly understood; the reaction 𝑁𝑂 ! " + * → * 𝑁𝑂 ! + 𝑒 " is an oxidation reaction that will be unfavorable under reducing conditions. One may also consider the reductive adsorption of nitric acid, HNO3. Given the dissociation equilibrium coefficient for nitric acid (~0.4 eV) , the availability of this species is likely vanishingly small (~1 in 10 7 based on a simple Boltzmann distribution) in an aqueous electrolyte. However, NO3 -reduction to NH3 is well documented in the literature, and so we assume a concerted two proton-electron transfer event, leading to adsorbed nitrite (*NO2), which is found to be very exergonic even close to 0 V vs. RHE. Exergonic nitrate adsorption within the range of potentials tested experimentally indicates spontaneous nitrate adsorption on the catalyst surface. Adsorption of CO2 is modeled via the reaction given in Eq. 2 as in previous works , given the weak binding nature of Ag: