Hexagonal Boron Nitride-Supported Crystalline Manganese Oxide Nanorods/Carbon: A Tunable Nanocomposite Catalyst for Dioxygen Electroreduction

Dioxygen reduction is a key step in low-temperature fuel cell catalysis research and ultimately of sustainable energy conversion technology. Herein, we report a simple strategy to design a cost-effective electrocatalyst comprising MnO2 nanorods on hexagonal boron nitride (h-BN) and their composite with high surface area carbon by a chemical method. The optimized nanocomposite catalyst (MnBN/C-75) exhibits a substantial higher onset potential (Eonset = 0.9 V vs RHE) and limiting kinetic current density (JL = 5.6 mA cm–2) during the oxygen reduction reaction (ORR) compared to other reported h-BN-based metal-supported or metal-free electrocatalysts. Moreover, this catalyst shows a ∼4-electron transfer pathway with a low peroxide (HO2–) intermediate yield during electroreduction of oxygen, indicating a single step, first-order kinetics as a commercial Pt/C catalyst. Besides, the mass activity of 222 mA mg–1 calculated at 0.6 V for the MnBN/C-75 catalyst is ∼21 times higher than that of MnBN (10.4 mA mg–1) and...