  By deintercalation of Na+ followed by inserting bilayers of water molecules
into the host lattice, the layered cobalt oxide of gamma-Na0.7CoO2 undergoes a
topotactic transformation to a layered cobalt oxyhydrate of
Na0.35(H2O)1.3CoO2-delta with the c-axis expanded from c = 10.9 anstrom to c =
19.6 anstrom. In this paper, we demonstrate that the superconducting phase of c
= 19.6 anstrom can be directly obtained by simply immersing gamma-Na0.7CoO2
powders in electrolyzed/oxidized (EO) water, which is readily available from a
commercial electrolyzed water generator. We found that high oxidation-reduction
potential of EO water drives the oxidation of the cobalt ions accompanying by
the formation of the superconductive c = 19.6 anstrom phase. Our results
demonstrate how EO water can be used to oxidize the cobalt ions and hence form
superconducting cobalt oxyhydrates in a clean and simple way and may provide an
economic and environment-friendly route to oxidize the transition metal of
complex metal oxides
