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In this paper, novel hierarchically mesoporous CeO2 nanoparticles assembled by hollow nanocones were prepared through a facile solvothermal strategy using Ce(HCOO)3 as the precursor. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FE-SEM) and thermal gravimetric analysis (TGA) were utilized to characterize the products and research the formation mechanism. The whole synthesis process involves two steps: formation of Ce(HCOO)3 nanoparticles constructed with nanocones at room temperature in an alkaline environment and oxidation induced phase transformation from Ce(HCOO)3 to CeO2 with formation of hollow nanocones assembled by nanocrystals in a solvothermal process at 150 °C. The as-prepared mesoporous CeO2 nanoparticles with an average diameter of 500 nm displayed a high surface area of 147.6 m² g-1 using N2 adsorption and desorption measurement. The H2-TPR test showed its great reduction behavior in a low temperature zone. By comparing the T100 temperature of CO conversion with a commercial sample (above 350 °C) and other reported samples (above 300 °C) in the literature, the mesoporous CeO2 nanoparticles (270 °C) presented an excellent catalytic activity for CO oxidation. [ABSTRACT FROM AUTHOR]

In this paper, a facile and economical route based on an oxidation induced phase transformation in alcoholic solution was developed to prepare mesoporous CeO2nanoflowers. The whole process could be divided into two steps: the formation of Ce(HCOO)3with flower-like structures and the oxidation induced phase transformation from Ce(HCOO)3to CeO2with unchanged morphology in the alcoholic solution. TEM results revealed that the CeO2nanoflowers consist of rods with length and diameter of 100 and 30 nm, respectively. N2adsorption/desorption experiments indicated that the CeO2nanoflowers display mesoporous structures with a mean pore size of 4 nm, and the BET surface area and pore volume of such flower-like structures are 95.7 m2g−1and 0.173 cm3g−1, respectively. Prompted by the mesoporous structure, high surface area and high pore volume, we speculate that these mesoporous CeO2flowers could be promising candidates for practical catalytic application. [ABSTRACT FROM AUTHOR]

Phase-pure porous nanospheres, both In(OH)3and InOOH, have been prepared through a facile hydrothermal method using different organic acids as the assistant agents. The organic acids play an important role in the phase change, and the phase composition of the precursors could be deliberately controlled by adjusting the organic acid (citric acid or tartaric acid). Cubic and hexagonal In2O3monodispersed nanospheres with porosity can be obtained from In(OH)3and InOOH, respectively, while size and morphology can be maintained to a certain extent. The as-synthesized porous In2O3nanospheres are composed of numerous small nanocrystallites and possess good size uniformity. Influencing factors such as the reaction time and the type and amount of organic acids were systematically investigated. A possible ethylenediamine or tartaric acid coordinated mechanism of the phase-control synthesis of In2O3was proposed based on the experimental results. Furthermore, the potentialities of the porous In2O3nanospheres were also studied by room-temperature photoluminescence (PL) spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, three dimensional mesoporous CeO2hierarchical structures were synthesized through the thermal decomposition of cerium formate precursors, which were prepared by a solvothermal method. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), and Thermal gravimetric (TG) was applied to characterize the precursors. Urchin-like Ce(HCOO)3precursors were prepared using dimethyl sulfoxide (DMSO) and ammonia solution (1 M) as solvent and base source, respectively, while coral-like Ce(HCOO)3precursors were prepared using dimethyl formamide (DMF) and NH4HCO3as solvent and base source, respectively. The formation mechanism of the hierarchical structured precursors was proposed involving a process of anisotropic growth–H2O induced self-assembly–oriented aggregation and disassembly–Ostwald ripening. CeO2hierarchical structures were obtained by annealing the corresponding Ce(HCOO)3precursors at 400 °C for 60 min. N2adsorption–desorption isotherms indicate that both CeO2hierarchical structures derived from their Ce(HCOO)3precursors display large surface areas and high pore volumes. In addition, the as-prepared CeO2catalysts with hierarchical structures are highly active for conversion of CO to CO2. [ABSTRACT FROM AUTHOR]

Large-scale uniform γ-AlOOH micro/nanoarchitectures (ellipsoidal flower-like, rotor-like, carambola-like and leaf-like) were synthesized through a facile one-step solution phase route. The products were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Influencing factors such as the volume ratio of DMF to water, the content of AlCl3, reaction temperature and reaction time were systematically investigated. A possible formation mechanism of the novel γ-AlOOH micro/nanostructures was proposed based on the experimental results. The room-temperature photoluminescence (PL) spectra of the obtained γ-AlOOH structures were also studied and the results indicate that the luminescence properties of the products are dependent on their morphologies. [ABSTRACT FROM AUTHOR]