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Rare earth element (La, Y, and Ce) modified MgAl-hydrotalcites of MgAlM were synthesized from coprecipitation and calcination, and further loaded with CoMo active species to give CoMo/MgAlM catalysts. X-ray powder diffraction, inductively coupled plasma, and N2 adsorption isotherms indicate that MgAlM possess large BET surface areas (58–91 m2/g), and rare earth elements were successfully introduced into samples. CO2-TPD (temperature-programmed desorption), NH3-TPD, H2-TPR (temperature-programmed reduction), H2S-TPS (temperature-programmed sulfidation), and Raman spectra indicate the presence of unique interactions between rare earth elements and Mo active species, which strongly affect the reduction and sulfidation behaviors of these catalysts. High resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis suggest that the addition of rare earth elements decreases the slab length and stacking numbers of MoS2 and promotes the sulfidation degree of Mo oxides. Th...

A network-structured SnO(2)/ZnO heterojunction nanocatalyst with high photocatalytic activity was successfully synthesized through a simple two-step solvothermal method. The as-synthesized samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, N(2) physical adsorption, and UV-vis spectroscopy. The results show that the SnO(2)/ZnO sample with a molar ratio of Sn/Zn = 1 is a mesoporous composite material composed of SnO(2) and ZnO. The photocatalytic activity of SnO(2)/ZnO heterojunction nanocatalysts for the degradation of methyl orange is much higher than those of solvothermally synthesized SnO(2) and ZnO samples, which can be attributed to the SnO(2)-ZnO heterojunction, the pore structure, and higher Brunauer-Emmett-Teller (BET) surface area of the sample: (1) The SnO(2)-ZnO heterojunction improves the separation of photogenerated electron-hole pairs due to the potential energy differences between SnO(2) and ZnO, thus enhancing the photocatalytic activity. (2) The SnO(2)/ZnO sample might possess more surface reaction sites and adsorb and transport more dye molecules due to the higher BET surface area and many pore channels, also leading to higher photocatalytic activity.

A high yield of nanostructured CuO bundles with different building blocks is successfully prepared through simple hydrothermal and thermal treatment methods. The microstructure of the as-synthesized samples is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 physisorption, and IR spectra. The results show that the microstructure of the CuO bundles, such as different grain sizes, BET surface areas, pore sizes, defects and morphologies of building blocks can be obtained by different synthetic methods. Moreover, H2-TPR and in situ XRD experiments are used to investigate the reduction properties of the nanostructured CuO bundles. It is found that there are two different reduction pathways involved in the reduction processes at 30 mL/min of 10 vol. % H2/N2: for the sample synthesized through the hydrothermal method (CuO-HT), all of the CuO is reduced directly to metallic Cu; however, for the sample synthesized through the thermal treatment method (CuO-TT), all of the CuO is ...

Ag/ZnO heterostructure nanocatalysts with Ag content of 1 wt % are successfully prepared through three different simple methods, where chemical reduction and photolysis reaction are adopted to fabricate the heterostructure. The dispersity of Ag clusters and/or nanoparticles in Ag/ZnO nanocatalyst is investigated by EDX mapping and XPS techniques. The experimental results show that deposition-precipitation is an efficient method to synthesize Ag/ZnO nanocatalyst with highly dispersed Ag clusters and/or nanoparticles; the photocatalytic activity of Ag/ZnO photocatalysts mainly depends on the dispersity of metallic Ag in Ag/ZnO nanocatalyst; the higher the dispersity of metallic Ag in Ag/ZnO nanocatalyst is, the higher the photocatalytic activity of Ag/ZnO photocatalyst should be. In addition, it is also found that the dispersity of Ag/ZnO photocatalyst in the dye solution is another key factor for liquid-phase photocatalysis due to the UV-light utilizing efficiency. The higher the UV-light utilizing efficiency is, the higher the photocatalytic activity of Ag/ZnO heterostructure photocatalyst should be.

A high yield of the dimer-type heterostructure of Ag/ZnO nanocrystals with different Ag contents is successfully prepared through a simple solvothermal method in the absence of surfactants. The samples are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and IR spectroscopy. The results show that all samples are composed of metallic Ag and ZnO; Ag nanoparticles locate on the surface of ZnO nanorods; the binding energy of Ag 3d(5/2) for the Ag/ZnO sample with a Ag content of 5.0 atom % shifts remarkably to the lower binding energy compared with the corresponding value of pure metallic Ag because of the interaction between Ag and ZnO nanocrystals; the concentration of oxygen vacancy for the as-synthesized samples varies with the increasing Ag content, and the Ag/ZnO sample with a Ag content of 5.0 atom % has the largest density of oxygen vacancy. In addition, the relationship between their structure and photocatalytic property is investigated in detail. It is found that the photocatalytic property is closely related to its structure, such as heterostructure, oxygen defect, and crystallinity. The presence of metallic Ag nanoparticles and oxygen vacancy on the surface of ZnO nanorods promotes the separation of photogenerated electron-hole pairs and thus enhances the photocatalytic activity.