Unraveling the Role of CeO<sub>2</sub> in Stabilization of Multivalent Mn Species on α-MnO<sub>2</sub>/Mn<sub>3</sub>O<sub>4</sub>/CeO<sub>2</sub>/C Surface for Enhanced Electrocatalysis
Bhugendra Chutia, Nayab Hussain, Panchanan Puzari, Deshetti Jampaiah, Suresh K. Bhargava, Е.В. Матус, И.З. Исмагилов, М. А. Керженцев, Pankaj Bharali
Abstract
A hybrid heteronanostructure of α-MnO2/Mn3O4/CeO2 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). CeO2 plays an essential role in increasing the surface Mn2+/3+/4+ in α-MnO2/Mn3O4/CeO2/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 mgMO–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-MnO2/Mn3O4/CeO2 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.