TiO2 Nanorod-Derived Synthesis of Upstanding Hexagonal Kassite Nanosheet Arrays: An Intermediate Route to Novel Nanoporous TiO2 Nanosheet Arrays

In this report, upstanding and nanoporous hexagonal TiO2 nanosheet arrays were achieved via using kassite [CaTi2O4(OH)2] as an intermediate. The process developed involved a TiO2 nanorod-derived synthesis of upstanding hexagonal kassite nanosheet arrays and a transformation of the kassite to TiO2. To the best of our knowledge, this is the first successful attempt to grow ordered hexagonal kassite nanosheet arrays. The as-obtained kassite nanosheets showed a single-crystalline nature with their c-axis parallel to the substrate. A stepwise study of the growth of the interesting hexagonal kassite nanosheet arrays was demonstrated. Upon hydrothermal treatment with diluted HNO3 aqueous solution, the single-crystalline hexagonal kassite got converted to nanoporous rutile TiO2, with shape preservation. The approach described in this study provides a novel method for the synthesis of kassite and TiO2 nanosheet arrays and are ready for a variety of applications such as in catalytic or optoelectronic fields.