Lawrence Berkeley National Laboratory

Shifting electrochemical oxygen reduction towards 2e^- pathway to hydrogen peroxide (H₂O₂), instead of the traditional 4e^- to water, becomes increasingly important as a green method for H₂O₂ generation. Here, through a flexible control of oxygen reduction pathways on different transition metal single atom coordination in carbon nanotube, we discovered Fe-C-O as an efficient H₂O₂ catalyst, with an unprecedented onset of 0.822 V versus reversible hydrogen electrode in 0.1 M KOH to deliver 0.1 mA cm^-2 H₂O₂ current, and a high H₂O₂ selectivity of above 95% in both alkaline and neutral pH. A wide range tuning of 2e^-/4e^- ORR pathways was achieved via different metal centers or neighboring metalloid coordination. Density functional theory calculations indicate that the Fe-C-O motifs, in a sharp contrast to the well-known Fe-C-N for 4e^-, are responsible for the H₂O₂ pathway. This iron single atom catalyst demonstrated an effective water disinfection as a representative application.