Efficient CO2 electroreduction in an acidic medium is challenging because the HER is normally more facile than CO2 reduction. It was reported that in CO2-saturated 0.1 M HClO4 solutions (pH =1), the Faradaic efficiency of HER was nearly 100% on Fe-N-C and Au 13 catalysts, both of which are efficient CO2 reduction catalysts in near neutral and alkaline media.