  Rational combination holds the key for non-precious metal oxides and economic
carbon materials to the creation of high performance air electrode materials.
Carbon nanotubes (CNTs)-supported manganese oxides composite catalysts (CMnCs)
were obtained by reacting commercial CNTs with MnO$_4^-$ in diluted H$_2$SO$_4$
with cancelling conventional hydrothermal processing or adding surfantant
templates. CMnCs were then assembled into commercial air cathodes equipped in
metal air fuel cells. CNTs demonstrated structurally much defective. Outer CNT
walls were cracked into graphene nano pieces yet remaining partially attached
to inner carbon tubes during synthesis. This exposure of graphene planes
exhibited additional oxygen reduction reactivity. Manganese oxide flakes
identified as {\gamma}-MnOOH were homogeneously grown on surfaces of CNTs at
nano sizes. Its deposition density was closely related to the additive amount
of KMnO$_4$ with regard to CNTs. The ORR activities of sole CMnCs exceeded both
raw CNTs and competent market catalysts under identical conditions, and with
current production technics the CMnCs-ingrediented air fuel cells were capable
of outputting ~15% more power at 100 mA/cm$^2$.
