Designing a MnF2/MnO2 heterostructure for enhanced electrocatalysis in the oxygen reduction reaction

Abstract

Studying noble-metal-free oxygen reduction reaction (ORR) catalysts is crucial for advancing fuel cells. Manganese dioxide (MnO2) has garnered widespread attention due to its convenient synthesis, low cost, high electrochemical activity, and diverse structures. However, it still faces challenges, such as poor conductivity and relatively lower inherent catalytic activity. In this study, a novel ORR electrocatalyst is introduced by constructing a heterostructure of manganese fluoride (MnF2) and MnO2, referred to as MnF2/MnO2. In a 0.1 M KOH solution, the ORR half-wave potential (E1/2) of MnF2/MnO2 is measured at 0.804 V, surpassing that of the original MnO2 catalyst (0.69 V). Compared to the MnO2 electrocatalyst, the MnF2/MnO2 heterostructure exhibits faster ORR reaction kinetics and a larger electrochemically active surface area. Density functional theory (DFT) calculations confirm that the MnF2/MnO2 heterostructure possesses enhanced intrinsic conductivity, facilitating the rapid transfer of ions of and electrons. Therefore, this study provides a promising pathway for enhancing the ORR catalytic activity of noble-metal-free electrocatalysts through rational heterostructure design.