Facile One-Pot Synthesis of alpha-MnO2/CeO2 Nanowires for Mg-Air Batteries

In this work, we synthesized MnO2/CeO2 electrocatalysts by in situ decoration of alpha-MnO2 with CeO2 particles during a one-step hydrothermal process. The morphology, composition, and electrochemical properties were studied in the context of application to the oxygen reduction reaction (ORR) and Mg-air battery. According to the results, alpha-MnO2/CeO2 microfibres exhibited better ORR performance than alpha-MnO2 microfibres due to the synergistic result between the introduction of Ce3+ in CeO2 lattice and the enhancement of Mn3+ content in MnO2 lattice. alpha-MnO2/CeO2 microfibres provided a higher surface area and more catalytic active sites than alpha-MnO2 microfibres by controlling the molar ratio of Ce3+/Mn7+ for the precursor. When the mole ratio of Ce3+ and Mn7+ in the precursors was 10%, the four-electron transfer process of the MnO2/CeO2 microfibres (MC-140-12-10) was found to be similar to that of the 20 wt% Pt/C commercial catalysts. MC-140-12-10 microfibres also showed the excellent long-term stability after 25,000 s and superior Mg-air battery performances than alpha-MnO2. Hence, the work paves the way for developing Mg-air batteries through a simple synthesis and cost-effective ORR catalyst.