Templated and bioinspired aqueous phase synthesis and characterization of mesoporous zirconia

X. Liu , Q. Ge , A. Rawal , G. Parada , Klaus Schmidt-Rohr , A. Akinc and S. K. Mallapragada
Sci. Adv. Mater.


Mesoporous zirconia has attracted great attention from the research community due to its unique properties such as high surface area, uniform pore size distribution, and large pore volume. Self-assembled structures have been used as directing agents to synthesize mesoporous zirconia. Here, we investigate the use of self-assembling block copolymers conjugated to cationic biomolecules such as lysozyme, as well as self-assembling cationic block copolymers as templates for synthesis of mesoporous zirconia in completely aqueous media. We believe this is the first report for synthesis of mesoporous zirconia in completely aqueous media with biomolecules, thereby opening up opportunities for different mechanisms for controlling zirconia synthesis. TGA was used to determine the inorganic content of the nanocomposite. XRD, nitrogen adsorption, TEM, SEM, SANS, and solid state NMR were employed to characterize the structure and composition of the samples. The results showed that zirconia nanocrystals formed after calcination of the as-synthesized nanocomposite at 500 °C, and significant crystal growth was observed only after 900 °C calcination. The conjugate-templated zirconia showed a surface area of 174 m2/g after calcination at 500 °C, and retained its tetragonal structure even after calcining at 900 °C. The cationic pentablock copolymer-templated zirconia showed the highest surface area, 191 m2/g, after calcination at 500 °C, and also demonstrated improved thermal stability. This bioinspired method can be easily scaled up and potentially used for synthesis of other oxides.