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

The development of alternative electrocatalysts exhibiting high oxygen reduction reaction (ORR) activity is vital for the deployment of large-scale clean energy devices, such as fuel cells and Zn-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 tuneable porosity. In this study, MnO nanoparticles entrapped N-doped mesoporous carbon compounds (MnO/NC) were developed as electrocatalysts for ORR, and their performances were evaluated in operational zinc-air batteries. It was found that the obtained carbon materials had large surface area and high electrocatalytic activity toward ORR. The carbon compounds were fabricated by using NaCl as a template via a one-pot process, which significantly simplifies the procedure for preparing mesoporous carbon materials in turn reducing the total cost. A primary zinc-air battery based upon this material exhibits an open circuit voltage (OCV) of 1.49 V, higher than conventional zinc-air batteries that use Pt/C (Pt/C cell) as the ORR catalyst (1.41 V). In our conditions, the assembled zinc-air battery delivered a peak power density of 168 mW cm-2 at a current density of ca. 200 mA cm-2, higher than 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 non-precious metal ORR catalyst for practical applications in metal-air batteries.