Macroporous Oxides of Group 4 Elements Ti,Zr

Three-dimensionally ordered macroporous crystalline Ti02 could be obtained by using titanium alkoxides as a metal source. Various titanium alkoxides [Ti(OEt)4, Ti(0 Pr)4, Ti(OBu)4] can be used in alcoholic solutions or neat.f After the titanium alkoxides have infiltrated the voids of the template, they can be solidified by drying in air (sometimes heated at ca 50 °C) by a sol-gel process. Another titanium source, ammonium lactate titanium dihydroxide, can be used. A gaseous Ti source, TiCE, can be used. Gaseous TiCU was deposited on a SiOi template, and then TiCU was hydrolysed with vaporous H2O. This two-step deposition of Ti02 on the template was repeated to deposit Ti02 in the voids of the template.  

A suspension of Ti02 nanoparticles can be used as a Ti source. Solid Ti02 nanoparticles can be packed into the voids of the template, and solidification is not necessary. ° Electrochemical deposition of Ti02 in the voids of templates is possible if the colloidal crystal templates are deposited on electrodes. Deposition of Ti02 by reacting (NH4)2TiF6 and H3BO3 in the voids of the template is possible if the surface of the template PS has been modified with carboxylic acid.  

By calcination of the solidified amorphous Ti02 materials at ca 450 °C anatase-phase Ti02 is formed, and the anatase-phase Ti02 can be transferred to rutile phase Ti02 by further calcination. 

A suspension of Zr02 nanoparticles suspension can be used as a Zr source. Solid Zr02 nanoparticles can be packed into the voids of the template, and solidification is not necessary. 

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