Résumé
We combined electrocatalytic measurements to reactive dynamics and meta-dynamics simulations in voltage-polarized conditions to reveal the mechanism of metal-free nanoporouscarbon-assisted-O2 reduction in an aqueous alkaline electrolyte. At 0V, pH=13 reduces a free energy barrier for O2 adsorption inside sub-nanopores. At 0.7V vs. RHE potential of a cathode, we observed O2 reduction through O2 splitting leading to OH -formation in these pores and, more substantially, in larger pores and at the external electrode surface. Reduction in these latter environments is induced by a strong and global surface electrostatic field that is the consequence of the ion docking in sub-nanopores. This results in a charge redistribution that mostly impacts electrode chemical and topological defects, leading to a spontaneous interfacial O2 reduction process. Overall, the metal-free nanoporous-carbon-assisted O2 reduction depends on the amount of sub-nanopores and defects in the pristine carbon electrode.