MnO/N-Doped Mesoporous Carbon as Advanced Oxygen Reduction Reaction Electrocatalyst for Zinc-Air Batteries.

The development of alternative electrocatalysts exhibiting high activity in the oxygen reduction reaction (ORR) is vital for the deployment of large-scale clean energy devices, such as fuel cells and zinc-air batteries. N-doped carbon materials offer a promising platform for the design and synthesis of electrocatalysts due to their high ORR activity, high surface area, and tunable porosity. In this study, materials in which MnO nanoparticles are entrapped in N-doped mesoporous carbon (MnO/NC) were developed as electrocatalysts for the ORR, and their performances were evaluated in zinc-air batteries. The obtained carbon materials had large surface area and high electrocatalytic activity toward the ORR. The carbon compounds were fabricated by using NaCl as template in a one-pot process, which significantly simplifies the procedure for preparing mesoporous carbon materials and in turn reduces the total cost. A primary zinc-air battery based on this material exhibits an open-circuit voltage of 1.49 V, which is higher than that of conventional zinc-air batteries with Pt/C (Pt/C cell) as ORR catalyst (1.41 V). The assembled zinc-air battery delivered a peak power density of 168 mW cm-2 at a current density of about 200 mA cm-2 , which is higher than that of an equivalent Pt/C cell (151 mW cm-2 at a current density of ca. 200 mA cm-2 ). The electrocatalytic data revealed that MnO/NC is a promising nonprecious-metal ORR catalyst for practical applications in metal-air batteries.