Biocatalytically Templated Synthesis of Titanium Dioxide

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• 作者：Jan L. Sumerel ; Wenjun Yang ; David Kisailus ; James C. Weaver ; Joon Hwan Choi ; and Daniel E. Morse
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：December 16, 2003
• 年：2003
• 卷：15
• 期：25
• 页码：4804 - 4809
• 全文大小：162K
• 年卷期：v.15,no.25(December 16, 2003)
• ISSN：1520-5002

文摘

Silicatein, an enzymatic biocatalyst purified from the glassy skeletal elements of a marinesponge, and previously shown capable of catalyzing and structurally directing the hydrolysisand polycondensation of silicon alkoxides to yield silica and silsesquioxanes at lowtemperature and pressure and neutral pH, is shown to be capable of catalyzing andtemplating the hydrolysis and subsequent polycondensation of a water-stable alkoxide-likeconjugate of titanium to form titanium dioxide. The structure and behavior of the TiO₂ formedthrough this biocatalytic route, including thermally induced crystal grain growth and phasetransformation from anatase to rutile, differ from those of TiO₂ formed from the sameprecursor via alkali catalysis or thermal pyrolysis. This enzymatic route affords a path totemplated synthesis that avoids the high temperatures and extremes of pH typically requiredfor synthesis of metallo-oxanes from the corresponding alkoxide-like precursors, and thusprovides access to a new and potentially useful parameter space of structures and properties.The proteins may also be nanoscopically structure-directing, as evidenced by the formationof nanocrystallites of anatase, a polymorph usually formed at much higher temperatures.The summation of weak interactions between the protein and mineral may induce thisstabilization and thus may afford a new level of nanostructural control, with associatedenhancement of selected performance properties.