The morphology effect of Zr-doped CeO_2 was studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zrdoped CeO_2 nanorods exhibited the highest catalytic performance(yield of styrene oxide and TOF value)followed by nanoparticles and nanocubes. For the Zr-doped CeO_2 nanorods, the apparent activation energy is 56.3 k J/mol, which is much lower than the values of catalysts supported on nanoparticles and nanocubes(73.3 and 93.4 k J/mol). The high resolution transmission electron microscopy results indicated that(100) and(110) crystal planes are predominantly exposed for Zr-doped CeO_2 nanorods while(100)and(111) for nanocubes,(111) for nanoparticles. The remarkably increased catalytic activity of the Zrdoped CeO_2 nanorods is mainly attributed to the higher percentage of Ce^(3+)species and more oxygen vacancies, which are associated with their exposed(100) and(110) crystal planes. Furthermore, recycling studies proved that the heterogeneous Zr-doped CeO_2 nanorods did not lose its initial high catalytic activity after five successive recycles.
