American Chemical Society, Chemistry of Materials, 1(22), p. 108-116, 2009
DOI: 10.1021/cm902500e
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Herein, we report a facile synthesis method for highly ordered hexagonal P6m mesoporous palladium doped titania nanoarchitectures using the F127 triblock copolymer as a template. The mesoporous Pd/TiO2 nanoarchitectures possess high surface areas of 223 m2g−1 and large pore volumes of 0.42 cm3g−1 at 300 °C that are reduced to 162 m2g−1 and 0.29 cm3g−1, respectively, as a result of calcination at 450 °C with their tunable mesopore diameter ranging from 5.7 to 8.3 nm. Transmission electron microscopy (TEM) measurements evince that the framework of the highly crystalline mesoporous Pd/TiO2 is composed of aligned anatase phase grown along the [101] direction. The Pd nanoparticles are well dispersed and exhibit sizes of about 20 nm and they are separated by 1.95 Å, which agrees with the (200) lattice spacing of face-centered cubic Pd. The newly prepared photocatalysts have been compared with Pd photodeposited onto the commercial photocatalyst Sachtleben Hombikat UV-100 by the determination of the rate of HCHO formation generated by the photocatalytic oxidation of CH3OH. This study revealed that hexagonal P6m mesoporous Pd/TiO2 nanoarchitectures possess a 2.5 times higher activity for the photooxidation of CH3OH than Pd/Hombikat UV-100. The photocatalytic oxidation of CH3OH using either highly ordered hexagonal networks in samples calcined at 350 °C, catalysts with randomly ordered mesoporous channels after calcinations at 450 °C or disordered mesostructures prepared at 550 °C are comparable although the crystallinity of the TiO2 nanoparticles increases strongly only with calcination temperatures exceeding 500 °C. From the economic point of view, ordered mesochannels prepared upon calcination at 450 °C are considered to be the optimum for saving energy in the photocatalyst preparation without much loss of photocatalytic performance.