Sonochemical preparation of stable porous MnO₂ and its application as an efficient electrocatalyst for oxygen reduction reaction

Porous MnO₂ as a non-noble metal oxygen reduction reaction (ORR) electrocatalyst was prepared by a simple sonochemical route. The as-prepared porous MnO₂ exhibited higher electrocatalytic activity, superior stability and better methanol tolerance than commercial Pt/C catalyst in alkaline media. Furthermore, the ORR proceeded via a nearly four-electron pathway. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) measurements verified that the ORR enhancement was attributed to the porous structure and good dispersity, which facilitated sufficient transport of ions, electrons, O₂ and other reactants in the process of ORR. The results indicated that a facile and feasible sonochemical route could be used to prepare highly active porous MnO₂ electrocatalyst for ORR, which might be promising for direct methanol fuel cells.