Synthesis of δ-MnO2/Reduced Graphene Oxide Hybrid In Situ and Application in Mg-Air Battery

Different forms of delta-MnO2 were constructed with their reduction sites anchored on non-support or other supports. Morphology, composition, and electrochemical properties of MnO2 and its hybrids were analyzed. Results revealed that MnO2/reduced graphene oxide (rGO) layered hybrid showed a higher BET surface area due to the synergistic effect on the introduction of rGO and the morphologic transformation of anchored MnO2. MnO2/rGO-2 exhibits a higher ratio of Mn3+: Mn4+ content, a better adsorption performance for O-2, and a lower charge-transfer resistance when respect to pristine delta-MnO2. Compared with other MnO2/rGO hybrids, porous MnO2/rGO-2 layered hybrid exhibits the best electrochemical property: a closer four-electron process (3.95), a more positive E ( onset ) (0.92 V vs RHE), and superior long-term durability (98.5% after 25,000 s). Especially, a mechanically reusable Mg-air battery with MnO2/rGO-2 cathode catalyst only exhibits a 5% decay for 264 h.

Automated summary

Different forms of delta-MnO2 with reduction sites anchored on non-supports or other supports were studied for their morphology, composition, and electrochemical properties. Results showed that the MnO2/rGO-2 layered hybrid exhibited higher BET surface area, superior adsorption performance, and lower charge-transfer resistance compared to other hybrids, especially showing excellent long-term durability. This suggests that the MnO2/rGO-2 hybrid could be a promising cathode catalyst for a mechanically reusable Mg-air battery with minimal decay over time.