Preparation of Porous TiO2 from an Iso-Polyoxotitanate Cluster for Rechargeable Sodium-Ion Batteries with High Performance

By aerobic calcination of a new titanium-oxide cluster (TOC) isolated from water, that is, [Ti6O8(OH2)20]·(2,7-NDS)4·2HCl·14H2O (Ti6-NDS; 2,7-NDS = 2,7-naphthalenedisulfonate), porous anatase TiO2 was facially prepared. The sample obtained at 400 °C exhibited a surface area of 108 cm3 g–1 and an average pore diameter of 16 nm. When used as an anode material for a sodium-ion battery (SIB), it showed larger specific capacity and far superior rate performance than the other TiO2 samples, including those prepared from another three TOCs under the same conditions or from Ti6-NDS under different conditions and the one obtained from a commercial source. The mechanistic study indicates that the hierarchical structure surrounding the Ti-oxide cores of Ti6-NDS is pivotal for the formation and the SIB performance of the porous TiO2. This surfactant-free and catalyst-free strategy for the fabrication of TiO2 materials with special morphologies by thermal transformation of a TOC provides a new optional protocol for the preparation of promising materials stable and efficient in SIBs.