SiO 2 -TiO 2 composite nanoparticle assemblies with or without alkyl surface modification and bearing a higher-order hollow spherical morphology were successfully synthesized by a simple, rapid, one-pot, and single-step solvothermal method using a precursor solution consisting of n-octyl-Si(OMe) 3 or Si(OEt) 4 , Ti(OiPr) 4 , o-phthalic acid, and acetic acid in methanol. The addition of acetic acid is essential for a high yield of nanoparticle assemblies with hollow spherical morphology and a high content of Si. The Si/Ti atomic ratio in the SiO 2 -TiO 2 com-
CeO 2 -ZrO 2 composite nanoparticles with mesoporous and spherical morphologies were assembled into different homogeneously dispersed, domain, and core-shell structures by changing the reaction conditions, such as the heating rate, acid, and solvent, in supercritical alcohols. Ce x Zr 1-x O 2 with homogeneous structures were prepared from Ce(NO 3 ) 3 and ZrO(NO 3 ) 2 in the presence of formic acid in methanol by rapid heating (500 °C/min) to 300 °C, while CeO 2 -ZrO 2 with domain structures were obtained by slow heating (5.4 °C/min). Treatment of mesoporous and spherical ZrO 2 nanoparticles with a Ce(NO 3 ) 3 solution in supercritical conditions yielded CeO 2 -ZrO 2 nanocomposites with core-shell morphologies, while solvents playing a key role in controlling the thickness of the outer shell; methanol produced a very thin outer shell structure of cubic CeO 2 and 2-propanol afforded a thick one.
The cover picture shows the SiO2–TiO2 composite MARIMO assemblies with and without alkyl groups synthesized directly by simple, one‐step, and one‐pot solvothermal reactions of Si alkoxides and a Ti alkoxide. A uniform spherical morphology with a porous shell and cavity was obtained. Properties such as the diameter and cavity size of these assemblies can be controlled by adjusting the ratio of the Si and Ti alkoxides in the precursor solutions, by adding a second acid, and by changing the reaction temperature. Details are discussed in the article by M. Ohtani, K. Kobiro et al. on page 3017 ff (https://doi.org/10.1002/ejic.201700253). For more on the story behind the cover research, see the Cover Profile (https://doi.org/10.1002/ejic.201700522).
Invited for the cover of this issue is the group of Kazuya Kobiro from Kochi University of Technology, Kochi, Japan. The cover image shows the one-pot and one-step synthesis of SiO 2 -TiO 2 composite nanoparticle assemblies with hollow spherical morphology.
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