Synthesis of Hollow Titania Powder by the Hydrothermal Method

Abstract

A layer‐by‐layer method is used to coat titania on spherical polystyrene (PS) powders in an aqueous solution. To increase surface charge density, a negatively charged PS powder is sequentially adsorbed by a cationic polyethylenimine (PEI)/anionic ammonium salt of poly(acrylic acid)/cationic PEI polyelectrolytes. A precursor of a negatively charged titanium bis‐ammonium lactate dihydroxide (TALH) is then precipitated onto the above positively charged PS. Repeating the coating processes of TALH/PEI in an aqueous solution, a uniform, multilayer TALH/PEI coating on PS powder is formed. A crystalline, spherical, hollow titania powder is then obtained by hydrothermal treatment of the above powder in an aqueous solution at temperatures higher than 350°C.

Template-free synthesis of mesoporous anatase titania hollow spheres and their enhanced photocatalysis

“…23 Among these, the template-mediated method is the most common manner, because of its effective and versatile synthesis of hollow structures, and it can be classified into two categories: hard templates (silica, polymer spheres, carbon, and CaCO 3 spheres) and soft templates (microemulsion droplets, ionic liquids, and bubbles). [24][25][26][27][28][29][30] However, the hard template method is quite complicated for it involves multiple steps of coating, etching, and calcination, while the soft template method cannot be well controlled to obtain uniform samples. Besides, the yield and size are restricted by the template.…”

Template-Free Fabrication of TiO2 Hollow Spheres and Their Photocatalytic Properties

“…To date, a variety of hard templates such as silica, − polymer spheres, − carbon, − and CaCO 3 spheres , or soft templates such as microemulsion droplets, ionic liquids, and bubbles − have been applied to direct the formation of hollow spheres by adsorption or chemical reaction on their surfaces, which have proven to be effective routes to many hollow nanostructures. These methods generally require multistep processes, in which the template will be removed by calcination or dissolution.…”

High-yield hydrothermal synthesis of mesoporous silica hollow capsules

“…This hydrothermal treatment was performed to promote the gelation of the silica sol and extension of the 3D ≡Si-O-Si≡ network to fabricate a rigid silica framework [14]. On the other hand, hydrothermal treatment at a temperature higher than the melting point of PS was shown to remove the PS particles and form hollow titania capsules [66]. These reports inspired us to improve the capsule yield through the use of hydrothermal treatment, because the treatment temperature can be dramatically reduced from the calcination temperature of 550 °C.…”