Titania and Silica Materials Derived from Chemically Dehydrated Porous Botanical Templates

• Published in: Chemistry of materials Vol. 24; no. 22; pp. 4301 - 4310
• Main Authors: Zimmerman, Andrew B, Nelson, Ashley M, Gillan, Edward G
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.11.2012
• Subjects: precursor; titania; chemical dehydration; silica; templating
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm3016534

This study describes the development of a mild room-temperature chemical dehydration method that effectively removes water from fragile living botanical leaf species without collapsing or physically degrading their macrostructure. The dehydrated plant materials retain an extensive vascular and cellular structure that was subsequently used as templating surfaces for metal oxide growth. The facile room-temperature chemical dehydration process used 2,2-dimethoxypropane (DMP) in acid-catalyzed reactions with water to yield methanol and acetone. The resulting chemically dehydrated botanical materials are relatively robust and retain their intricate internal cellular and vascular structures with little reduction in physical size despite the removal of over 70% of their original mass. Dehydrated botanical templates from several different leaf species were used to produce titania and silica structures. Water reactive titanium and silicon alkoxide precursors were incorporated into the DMP dried templates through a simple benchtop liquid absorption method. Subsequent hydrolysis, pyrolysis, and calcination in air removed the template’s cellulose framework and yielded crystalline anatase TiO2 at 475 °C or crystobalite SiO2 at 1000 °C. The oxide monoliths retain large portions of the original plant’s macroscopic and microscopic cellular structure. Challenges related to using botanical materials as inorganic structure templates are highlighted. DMP dehydration methods provide access to a potentially very diverse set of living botanical species as templates to inorganic materials with nature-inspired structures.