A Simple Synthetic Approach to Al₂O₃–TiO₂ and ZnO–TiO₂ Mesoporous Hollow Composite Assemblies Consisting of Homogeneously Mixed Primary Particles at the Nano Level

Abstract

A simple synthetic approach to Al2O3–TiO2 and ZnO–TiO2 mesoporous hollow composite assemblies consisting of homogeneously mixed primary particles at the nano scale was demonstrated. The composites, Al2O3–TiO2 and ZnO–TiO2, have a large specific surface area (250–600 m2 g–1) and were synthesized by high‐temperature and high‐pressure treatment of precursor solutions containing Al(OiPr)3 or Zn(OAc)2, Ti(OiPr)4, and phthalic acid in methanol. Aggregated, fused spherical, and individual spherical morphologies of the hollow assemblies with amorphous Al2O3 and anatase TiO2 were obtained, depending on the Al/Ti ratio of the precursor solutions. Hollow spherical composite assemblies with amorphous ZnO and anatase TiO2 phases were obtained by treating precursor solutions with lower Zn contents (5–25 %). A phase transition from anatase to rutile was not observed for the Al2O3–TiO2 composite assemblies (50 % Al) even at 1000 °C. The band gap energies of the ZnO–TiO2 hollow assemblies were tuned (3.12–3.21 eV) by changing their Zn content.

Porous niobia spheres with large surface area: alcothermal synthesis and controlling of their composition and phase transition behaviour

“…However, this crystalline growth of TiO 2 was not observed for the Al 2 O 3 -TiO 2 , ZnO-TiO 2 , and SiO 2 -TiO 2 composites. 11,12 Thus, the observed crystalline growth of TiO 2 can be ascribed to the catalytic effect of solid Nb 2 O 5 as a solid acid that promoted crystalline growth.…”

“…36 As mentioned in the introduction, composite MARIMOs consisting of plural metal oxides have been successfully synthesized. [10][11][12][13] Herein, a one-pot and single-step technique was used to obtain TiO 2 -Nb 2 O 5 composite MARIMOs.…”

Solvothermal synthesis of hair-like carbon nanotubes onto sub-micron-sized spherical metal oxide catalyst cores

“…We called these structures meso-/micro-porously architected roundly integrated metal oxide (MARIMO) particles. 15 Composite MARIMOs, including several metal oxides, were synthesized easily using the solvothermal method, including Al 2 O 3 /TiO 2 , 23 SiO 2 /TiO 2 , 24 Nb 2 O 5 /TiO 2 , 25 SiO 2 /ZrO 2 , 26 ZrO 2 /CeO 2 , 27 PO x /SnO 2 , 21 and CoO x /MnO y particles. 28 Industrial scale synthesis of some of these materials is also possible.…”

One‐Step Direct Synthesis of SiO2–TiO2 Composite Nanoparticle Assemblies with Hollow Spherical Morphology

“…spherical morphologies. [29][30][31] We named these NP assemblies micro/mesoporously architected roundly integrated metal oxides (MARIMOs). Various MARIMO assemblies such as SiO 2 , TiO 2 , ZnO, ZrO 2 , and CeO 2 , as well as their composites such as TiO 2 -ZnO, TiO 2 -Al 2 O 3 , ZrO 2 -CeO 2 , and In-Ga-Zn oxide, were prepared by a similar method from precursor solutions consisting of mixed metal alkoxides and/or salts, which demonstrates the versatility of the solvothermal method.…”

“…We have recently developed a new solvothermal approach to fabricate metal oxide NP assemblies with solid or hollow spherical morphologies . We named these NP assemblies m icro/ m esoporously a rchitected r oundly i ntegrated m etal o xides (MARIMOs).…”