Materials Science

In Rare Titania Form

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Science  15 Nov 2013:
Vol. 342, Issue 6160, pp. 778
DOI: 10.1126/science.342.6160.778-c
CREDIT: ATSUSHI KONDO/ TOKYO UNIVERSITY OF AGRICULTURE AND TECHNOLOGY

One route for synthesizing mesoporous and microporous inorganic materials is to use an organic material as a template, such as a surfactant or a block copolymer, but the resulting pore network can be disordered. Hall et al. show that the inherent microporosity of a metal-organic framework (MOF) compound can be used to template an ordered microporous form of titanium oxide. They used the MOF HKUST-1, in which copper ions linked together by benzene-1,3,5-tricarboxylate ligands create a network of 1-nm pores. The material was impregnated with a metal oxide precursor, titanium(IV) isopropoxide, and then underwent a hydrothermal treatment at 200°C for 20 hours in a water-ethanol solvent. This product was treated with acid and then hydrogen peroxide. These procedures removed almost all of the MOF framework, although some copper and residual carbon were retained. Transmission electron microscopy and x-ray diffraction studies showed that the morphology of the HKUST-1 template and the pore size of 1 nm were retained in the metal oxide. These studies also revealed that the phase of titania is brookite, which probably formed instead of the more common rutile or anatase phases because of the presence of copper ions. However, nitrogen adsorption-desorption studies revealed that disordered mesopores are present, which probably resulted from incomplete pore filling by the precursor.

J. Am. Chem. Soc. 135, 10.1021/ja4083254 (2013).

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