Unraveling the Role of CeO2 in Stabilization of Multivalent Mn Species on α-MnO2/Mn3O4/CeO2/C Surface for Enhanced Electrocatalysis

A hybrid heteronanostructure of α-MnO 2 /Mn 3 O 4 /CeO 2 with the atomic-level coupled nanointerface entrenched in Vulcan carbon is reported and explored for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). CeO 2 plays an essential role in increasing the surface Mn 2+/3+/4+ in α-MnO 2 /Mn 3 O 4 /CeO 2 /C for ORR/OER processes. It shows enhanced bifunctional activity, superior to that of the benchmark 20 wt % Pt/C and Pd/C catalysts. It displays an ORR onset potential of −0.13 V (vs Ag/AgCl), limiting current density of −6.63 mA cm –2 (at 1600 rpm), mass-specific current of 47.6 mA mg MO –1 with a lower Tafel slope (921.9 mV dec –1 ), and an inclusive 4-e transfer involved in ORR. The OER onset potential and current density are 0.58 V (vs Ag/AgCl) and 8.45 mA cm –2 (at 0.8 V). The unique hybrid structure with oxide–oxide interface in α-MnO 2 /Mn 3 O 4 /CeO 2 is correlated to explain the mechanistic pathway. Multistate Mn(II/III/IV) and Ce(III/IV) synergistically influence in tendering superior activity with enhanced stability.