Well-crystallized mesoporous TiO2 shells for enhanced photocatalytic activity: prepared by carbon coating and silica-protected calcination

Abstract

Mesoporous anatase-phase TiO2 hollow shells were successfully fabricated by the solvothermal and calcination process. This method involves preparation of SiO2@TiO2 core-shell colloidal templates, sequential deposition of carbon and then silica layers through solvothermal and sol-gel processes, crystallization of TiO2 by calcination and finally removal of the inner and outer silica to produce hollow anatase TiO2 shells. The prepared samples were characterized by transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption isotherms and UV-vis absorption spectroscopy. The results show that a uniform carbon layer is coated on the core-shell particles through the solvothermal process. The combustion of carbon offers the space for the TiO2 to further grow into large crystal grains, and the outer silica layer serves as a barrier against the excessive growth of anatase TiO2 nanocrystals. Furthermore, the initial crystallization of TiO2 generated in the carbon coating step and the heat generated by the combustion of the carbon layer allow the crystallization of TiO2 at a relatively low temperature without changing the uniform structure. When used as photocatalysts for the oxidation decomposition of Rhodamine B in aqueous solution under UV irradiation, the hollow TiO2 shells showed enhanced catalytic activity. Moreover, the TiO2 hollow shells prepared with optimal crystallinity by this method showed a higher performance than commercial P25 TiO2.

A 3D hierarchical magnetic Fe@Pt/Ti(OH)4 nanoarchitecture for sinter-resistant catalyst

“…5,24 Furthermore, the a-Fe 2 O 3 @C/Pt composite was coated with a layer of amorphous TiO 2 , by using titanium tetrabutoxide (TBOT) as the TiO 2 precursor, hydroxypropyl cellulose (HPC) as a surfactant, and ethanol as the reaction medium. 12,35 As shown in Fig. 4d), indicating the successful synthesis of the a-Fe 2 O 3 @C/Pt/TiO 2 nanocomposite.…”

“…The higher interaction between the Pt NPs and TiO 2 can promote the performance of the nanocatalyst 12,35. S5, † the (103) and (101) planes of TiO 2 could demonstrate the existence of TiO 2 aer calcination.…”

A highly reactive and enhanced thermal stability nanocomposite catalyst based on Pt nanoparticles assembled in the inner surface of mesoporous SiO2 spherical shell

“…The mesoporous silica layer was constructed via a modified Stöber method [30], using CTAB as a template [19]. In brief, 100 mg of the Pt/ NCSs were added into a solution containing 60 mL of water, 30 mL of ethanol, 150 mg of CTAB, and 0.55 mL of ammonia aqueous solution under mildly stirring for 1 h to form a homogeneous solution.…”

“…2d shows an image of the beads after deposition of the mesoporous silica layer (ca. 155 nm in thickness) via a modified Stöber method [30], in which CTAB was used as pore-forming agent. Subsequently, CTAB templates were removed by treating with refluxing acetone and then a uniform mesoporous silica shell with cylindrical channels was formed.…”

The investigation of Ag decorated double‐wall hollow TiO2 spheres as photocatalyst

“…During the past several decades, photocatalytic degradation of organic pollutant has aroused worldwide attention for the urgent requirements of a clean environment . As an excellent semiconductor photocatalyst, titanium dioxide (TiO 2 ) has been widely applied in various environmental areas for its low cost, nontoxicity, biocompatibility and photoreactivity .…”