Synthesis of TiO2 nanotube networks from the mineralization of swim bladder membrane in supercritical CO2

In this work, a green route to prepare TiO2 nanotube networks using swim bladder (SB) membrane as a bio-template was reported. In this method, the SB membrane was first dried with CO2 extraction, which resulted in the fibrous structures of SB membrane. With the CO2-dried SB membrane as bio-template, TiO2 were obtained via the surface sol–gel reaction of titanium isopropoxide on the fibers of SB membrane in supercritical CO2, followed by the removal of SB membrane calcined at 600 °C. The resulting TiO2 was characterized with scanning electron microscopy, transmission electron microscopy and X-ray diffraction. It was indicated that ordered anatase nanotube networks were produced. Compared to the conventional sol–gel method, the protocol adopted in this work could produce TiO2 nanotubes with regular and ordered structures.