The former pathway is preferred in fuel cell applications to maximize the energy conversion efficiencies 1, 2, 3, and the latter one represents a green synthetic method for H 2O 2 4, 5, 6, 7. Molecular oxygen (O 2) can be electrochemically reduced to water (H 2O) via a 4e – pathway, or hydrogen peroxide (H 2O 2) with 2e – transferred in aqueous solutions. This iron single atom catalyst demonstrated an effective water disinfection as a representative application. 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 H 2O 2 pathway.
A wide range tuning of 2e –/4e – ORR pathways was achieved via different metal centers or neighboring metalloid coordination.
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 H 2O 2 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 H 2O 2 current, and a high H 2O 2 selectivity of above 95% in both alkaline and neutral pH. Shifting electrochemical oxygen reduction towards 2e – pathway to hydrogen peroxide (H 2O 2), instead of the traditional 4e – to water, becomes increasingly important as a green method for H 2O 2 generation.
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