LaFeO3 perovskite with a porous fibrous structure was successfully synthesized using a sunflower seed shell as a template. To investigate the effects of this template, a sample was prepared without a template via the same procedure. Through various characterization techniques, such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy, oxygen temperature programed desorption, and hydrogen temperature programed reduction, the physiochemical properties of the samples were investigated. The results showed that the sample made with a template had a larger surface area and a larger amount of adsorbed oxygen, which further illustrated that the sunflower seed shell template had a significant impact on the physiochemical properties of the samples. Furthermore, we explored the catalytic activity for nitric oxide (NO) oxidation, and studied the factors affecting it, which highlighted its potential application in automobile exhausts.

The yolk–shell LaMnO3 perovskite microspheres were fabricated by a novel, simple and mild soft template approach. A series of template-P123 concentrations (0–6.12 mmol∙L−1) were employed to optimize the most complete spheres. When the concentration of P123 is 3.0 mmol·L−1, the obtained yolk–shell microspheres with a diameter of 200–700 nm were constructed by nanoparticles. The possible formation mechanism of the yolk–shell microspheres was revealed step by step via XRD, SEM, TEM, EDS and HRTEM. Molecules of P123 were suitably mixed with solvents for double shelled vesicles through self-assembly, which interacted with metal complexes to form P123–metal vesicles. After the removal of P123 and citric acid by calcination at 700 °C, the yolk–shell LaMnO3 microspheres with through-channels were obtained. Through-channels on the surface were due to citric acid and the solid core was attributed to the shrink of inner vesicles. Prepared yolk–shell microsphere samples possessed a larger surface area and a higher maximum NO conversion value of 78% at 314 °C for NO oxidation, compared with samples without the yolk–shell structure.

La1-xPrxMnO3(x = 0, 0.05, 0.1, ..., 0.4) perovskites were prepared readily via citric acid sol-gel method in the present study. Several characterization techniques have been employed, such as X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Brunauer-Emmett-Teller (BET), N-2 adsorption-desorption analyses, Oxygen temperature-programmed desorption (O-2-TPD), Hydrogen temperature-programmed reduction (H-2-TPR) and NO temperature-programmed desorption (NO-TPD), with the aim of exploring the effects of Pr substitution. Then the samples were submitted to activity test in catalytic NO oxidation. NO conversion was improved with the increase of Pr substitution when x <= 0.2, and then decreased with further addition of Pr. The most excellent catalytic activity with NO conversion of 91% at 260 degrees C was observed on La0.8Pr0.2MnO3. It was revealed that the appropriate Pr addition (x <= 0.2) at A-site led to the modified reducibility of LaMnO3, as well as the increased molar ratio of Mn4+/Mn3+ and O-ads/O-total, which was benificial for NO oxidation. Moreover, the increase of NO adsorption amount and the shift of the decomposition temperature of nitrates to lower temperautre with the aid of appropriate Pr component accounted for the enhanced activity.

In this paper, pomelo peel was used as biological template to obtain hierarchically porous LaFeO3 perovskite for the catalytic oxidation of NO to NO2. In addition, X-ray diffraction (XRD), scanning electron microscopy (SEM), N-2 adsorption desorption analyses, X-ray photoelectron spectra (XPS), NO temperature-programmed desorption (NO-TPD), oxygen temperature-programmed desorption (O-2-TPD) and hydrogen temperature-programmed reduction (H-2-TPR) were used to investigate the micro-structure and the redox properties of the hierarchically porous LaFeO3 perovskite prepared from pomelo peel biological template and the LaFeO3 perovskite without the biological template. The results indicated that the hierarchically porous LaFeO3 perovskite successfully replicated the porous structure of pomelo peel with high specific surface area. Compared to the LaFeO3 perovskite prepared without the pomelo peel template, the hierarchically porous LaFeO3 perovskite showed better catalytic oxidization of NO to NO2 under the same conditions. The maximum NO conversions for LaFeO3 prepared with and without template were 90% at 305 degrees C and 76% at 313 degrees C, respectively. This is mainly attributed to the higher ratio of Fe4+/Fe3+, the hierarchically porous structure with more adsorbed oxygen species and higher surface area for the hierarchically porous LaFeO3 perovskite compared with the sample prepared without the pomelo peel template.

Hierarchically porous LaFeO3 perovskites are synthesized through a facile process by using pomelo peel as a biotemplate.

Uniform magnetic hollow nanospheres (GdNi2, Co5Gd) coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2) spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniformnanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

Ni/xY2O3–Al2O3 (x = 5, 10, 15, 20 wt%) catalysts were prepared by sequential impregnation synthesis. The catalytic performance for the autothermal reforming of methane was evaluated and compared with Ni/γ-Al2O3 catalyst. The physicochemical properties of catalysts were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-Ray Photoelectron Spectrometer (XPS), Thermo Gravimetric Analyzer (TGA) and H2-temperature programmed reduction techniques (TPR). The decrease of nickel particle size and the change of reducibility were found with Y modification. The CH4 conversion increased with elevating levels of Y2O3 from 5% to 10%, then decreased with Y content from 10% to 20%. Ni/xY2O3–Al2O3 catalysts maintained high activity after 24 h on stream, while Ni/Al2O3 had a significant deactivation. The characterization of spent catalysts indicated that the addition of Y retarded Ni sintering and decreased the amount of coke.

Perovskite-type oxides La 0.8Ce 0.2Mn 1-x Cu xO 3(x=0.2, 0.3, 0.4), La 0.8Sr 0.2Mn 0.6 Cu 0.4O 3, and La 0.8Ce 0.1Sr 0.1Mn 0.6 Cu 0.4O 3 were prepared by citrate sol-gel method, and characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET) and the X-ray photoelectron spectroscopy (XPS). Their catalytic activities for removal of NO+CO were also investigated. The results indicated that La 0.8Ce 0.1Sr 0.2Mn 0.6 Cu 0.4O 3 showed the highest catalytic activity, i.e. the conversion of CO and NO had reached 91.8% at 150°C and 100% at 300°C respectively. The specific surface area, grain size and spread of solid particles were the major factors affected the catalytic activity for La 0.8Ce 0.2Mn 1-x Cu xO 3 (x=0.2, 0.3, 0.4), while the composition was the key factor affected the catalytic activity for La 0.8Ce 0.2Mn 0.6 Cu 0.4O 3, La 0.8Sr 0.2Mn 0.6 Cu 0.4O 3 and La 0.8Ce 0.1Sr 0.1Mn 0.6 Cu 0.4O 3.

Uniform rare-earth gadolinium oxide (Gd2O3) hollow spheres with tunable shell thickness have been successfully fabricated in the presence of SiO2 as templates via a urea-based homogeneous precipitation method. The synthesis is a mild, low-cost and convenient method without any catalysts. By varying the times of the precipitation procedure, the shell thickness can be successfully controlled within the 20-55 nm range. The thickness increase of each coating might be similar to 10 nm. The as-synthesised product was identified from X-ray diffraction pattern, scanning electron microscopy and energy dispersive X-ray. The prepared hollow Gd2O3 spheres with tunable shell thickness and fluorescence property have the potential to be used for drug delivery, fluorescent labelling and controlled release applications.

Uniform magnetic hollow nanospheres (GdNi , Co Gd) coated with Gd O have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO ) spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.