TY - JOUR
T1 - Facile preparation of transparent monolithic titania gels utilizing a chelating ligand and mineral salts
AU - Hasegawa, George
AU - Kanamori, Kazuyoshi
AU - Nakanishi, Kazuki
AU - Hanada, Teiichi
N1 - Funding Information:
Acknowledgments The Grant-in-Aid for Scientific Research (No. 20750177 for K. K. and No. 20350094 for K. N.) and the Global COE Program ‘‘International Center for Integrated Research and Advanced Education in Materials Science’’ (No. B-09) both from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, are acknowledged. Also, partly supported by a Grant for Practical Application of University R&D Results under the Matching Fund Method from New Energy and Industrial Technology Development Organization (NEDO), Japan.
PY - 2010/1
Y1 - 2010/1
N2 - Highly homogeneous transparent titania gels have been successfully prepared from titanium alkoxide by a sol-gel method utilizing chelating agent, ethyl acetylacetate (EtAcAc), in the presence of strong acid anions. Only catalytic amount of a strong acid anion suppress the rapid hydrolysis of titanium alkoxide by blocking the nucleophilic attack of HO- and H2O, and the resultant moderate sol-gel reactions thus afford homogeneous gelation, leading to transparent monolithic titania gels. Gelation time can be widely controlled by changing amounts of water, chelating agent and salt. The ability of salts to suppress the too abrupt sol-gel reactions is strongly dependent on the electronegativity of anions and valence of cations. With employing NH 4NO3 as a suppressing electrolyte, the obtained titania gels can be converted to pure TiO2 by simple washing and heat-treatment, and transformations to anatase and rutile structures were found to start at 400 and 600 °C, respectively.
AB - Highly homogeneous transparent titania gels have been successfully prepared from titanium alkoxide by a sol-gel method utilizing chelating agent, ethyl acetylacetate (EtAcAc), in the presence of strong acid anions. Only catalytic amount of a strong acid anion suppress the rapid hydrolysis of titanium alkoxide by blocking the nucleophilic attack of HO- and H2O, and the resultant moderate sol-gel reactions thus afford homogeneous gelation, leading to transparent monolithic titania gels. Gelation time can be widely controlled by changing amounts of water, chelating agent and salt. The ability of salts to suppress the too abrupt sol-gel reactions is strongly dependent on the electronegativity of anions and valence of cations. With employing NH 4NO3 as a suppressing electrolyte, the obtained titania gels can be converted to pure TiO2 by simple washing and heat-treatment, and transformations to anatase and rutile structures were found to start at 400 and 600 °C, respectively.
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U2 - 10.1007/s10971-009-2056-5
DO - 10.1007/s10971-009-2056-5
M3 - Article
AN - SCOPUS:74849093108
SN - 0928-0707
VL - 53
SP - 59
EP - 66
JO - Journal of Sol-Gel Science and Technology
JF - Journal of Sol-Gel Science and Technology
IS - 1
ER -