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Mesoporous PrOy–ZrO2 materials were obtained by coprecipitation process. XRD patterns and TEM images reveal pore size growth with increase in the calcining temperature. N2 adsorption–desorption isotherms of the PrOy–ZrO2 samples are indicative of type IV behavior characteristic of mesoporous materials (as evidenced by low-angle XRD patterns). PrOy–ZrO2 calcined at 500 and 650 °C show well-developed H2 type hysteresis loops, indicating the existence of ink-bottle-like pores with a narrow entrance and a large cavity. PrOy–ZrO2 calcined at 800 and 950 °C show H1 type hysteresis loops, which is often associated with porous materials known to consist of agglomerates of approximately uniform spheres, and hence to have narrow distributions of pore size. The phase analysis by Rietveld refinement method clearly shows the formation of cubic PrOy–ZrO2 solid solution from 500 to 950 °C.

Using Cerium chloride octahydrate as a precursor and dodecyl sodium sulfate as a template, nano-sized CeO 2 with extra-high surface area were synthesized by a surfactant-templated method. The highest surface area of the synthesized CeO 2 was 457 m 2 g − 1 . Combined with XRD, TEM and BET results, it was found that when the calcination temperature was lower than 600 °C, the particle size of CeO 2 hardly changed while the surface area declined due to the co-action of the sintering and agglomeration of the particles. However, with a high calcination temperature (above 600 °C), the sintering was the mainly reason to the decline of the BET surface area and the rapid growth of the particles size. Moreover, by the test for CO oxidation, it was found that the reactivity of the CeO 2 sample remarkably increased with decreasing particle size, which was due to the fact that smaller particles provided more structural defects.