In a beaker, lithium hydroxide, dissolved in 10 mL water, was mixed under vigorous stirring together with ammonium dihydrogen phosphate and phosphoric acid in 10 mL water. Then 10 mL aqueous solutions of manganese and iron sulfate together with acetic acid were added and the mixture was evenly distributed to four 80 mL quartz vessels. The reaction vessels were placed in the rotor, which was closed with the lid and subjected to microwave irradiation at constant 400 W.
After cooling, the product was repeatedly centrifuged and washed with acetone and water. After drying at 70 °C overnight, the powder was sintered at 600 °C for 6 h under an Ar/H2 atmosphere (95:5).
Finally, the dried nanopowder was mixed in an 80 mL quartz vessel with commercially available carbon nanotubes under sonication and again subjected to microwave irradiation at constant 400 W.