Here we have investigated the role of phosphate anions and utilization of an 𝑣 𝑂 under the conditions considered here (i.e. FTO and C-Felt). Further, selectivity towards intermediately-oxidized nitrogenous species (nitrite) is slightly enhanced when supporting Cu with CeO2-δ relative to supporting with C-Felt. This may be due to CeO2-δ enhancing the coverage of nitrate over competitive hydrogen adsorption, or perhaps by a more dynamic process where adsorption and cleavage of the nitrate N-O bond heals 𝑣 𝑂 •• within CeO2-δ and modifies of the adsorption energy of the now stoichiometric CeO2. The use of oxide supports to increase NO3RR activity may then also provide a strategy to tailor reaction products for any number of oxygen redox electrosynthesis reactions.