High-performance MnO/N-rGO catalyst for half-cell and Zn-air batteries by photochemically assisted synthesis

The vigorous development of efficient cathode-side oxygen reduction reaction (ORR) catalysts is one of the keys to the practical application of fuel cells and Zn-air batteries (ZABs). Herein, a facile and green photochemical method is developed to synthesize pure-phase Mn3O4 nanoparticles, which are uniformly anchored on nitrogen -doped reduced graphene oxide (N-rGO), followed by simple one-step annealing to highly catalytical active and stable MnO/N-rGO. The resultant MnO/N-rGO exhibits exciting ORR performance in alkaline media. Particu-larly, both GDE (gas diffusion electrode) half-cell and ZABs assembled from MnO/N-rGO have excellent overall performance and outstanding long-term durability, obviously better than Pt/C-based GDE half-cell and Pt/C + RuO2-based ZABs, respectively. It is mainly attributed to the synergistic effect between MnO nanoparticles and N-rGO support, which significantly increases the active sites and facilitates 4-electron transfer. This research paves a way for the green photochemical synthesis of transition metal oxide ORR catalysts at room temperature.