This ex situ electrochemical study investigates how the oxygen reduction reaction (ORR) on Bi-doped Ca2Ru2O7 pyrochlore catalysts is affected by the addition of carbonate to the aqueous KOH (1 mol dm ) electrolyte. The parent Ca2Ru2O7 catalyst has been previously reported to be selective towards the generation of CO3 2– on the reaction of O2 with CO2 (in the presence of H2O) at the cathode of l...