Layered sodium titanate nanofiber and microsphere synthesized from peroxotitanic acid solution

In this paper, we report titania and titanate nanofiber synthesized by using peroxotitanic acid solution as a titanium source. The peroxotitanic acid solution was mixed with NaOH aqueous solution, followed by the hydrothermal treatment with or without vigorous agitation. In TEM and SEM images for solids obtained by the synthesis with vigorous agitation, nanofibers are observed. On the other hand, microspheres as well as nanofibers were observed in solids obtained by the synthesis without agitation. The microspheres are composed of nanofibers and nanosheets. EDX analysis for the obtained solids detected Ti and Na, indicating that the obtained solids are sodium titanate. As a reference, synthesis by using TiO2 particles instead of the peroxotitanic acid solution was also performed. The Na to Ti mole ratio for the peroxotitanic acid based solid determined by EDX was 0.55 which is twice the value of 0.26 for the TiO2 particle based solid. The obtained sodium titanate could be converted into anatase-type titania by the HCl treatment of the sodium titanate and the subsequent calcination.