We report on the rapid production, characterization, and spectral properties of highly uniform, ultra narrow semiconductor (ZnS, ZnSe, CdS, CdSe) nanorods and nanowires by microwave irradiation. Quantum-confinement effects are manifested in the light absorption and the PL of the rods and wires. The uniformity of the rods and of the wires is demonstrated in their spontaneous assembly into highly ordered 2D supercrystals. We also observed the stepwise growth of the rods originating from nearly spherical nuclei.

We report the microwave synthesis and characterization of Au and Pd nanoparticle catalysts supported on CeO2, CuO, and ZnO nanoparticles for CO oxidation. The results indicate that supported Au/CeO2 catalysts exhibit excellent activity for low-temperature CO oxidation. The Pd/CeO2 catalyst shows a uniform dispersion of Pd nanoparticles with a narrow size distribution within the ceria support. A remarkable enhancement of the catalytic activity is observed and directly correlated with the change in the morphology of the supported catalyst and the efficient dispersion of the active metal on the support achieved by using capping agents during the microwave synthesis. The significance of the current method lies mainly in its simplicity, flexibility, and the control of the different factors that determine the activity of the nanoparticle catalysts.

We report on the rapid production, characterization, and spectral properties of uniform nanorods, nanowires, and nanoplates of rare earth oxides (M 2 O 3 , M ) Pr, Nd, Sm, Eu, Gd, Tb, Dy). The method developed, based on microwave irradiation (MWI), allows the control of the size and shape of the rare earth oxide nanostructures by varying the MWI reaction time and the relative concentrations of the organic surfactants. The uniformity of the rods and of the wires is demonstrated in their spontaneous assembly into highly ordered 2D supercrystals.The MWI method provides a unique opportunity for the large-scale synthesis of rare earth nanostructures without suffering thermal gradient effects.

We report the vapor phase synthesis of upconverting Y2O3 nanocrystals doped with Yb3+, Er3+, Ho3+, and Tm3+ to generate red, green, blue, and white light. Incorporating Er3+ within the Yb3+ doped Y2O3 nanocrystals under 980 nm laser excitation produced orange and yellow upconversion luminescence tunable by varying the Yb3+ concentration. The Yb3+, Er3+, and Tm3+ codoped Y2O3 nanocrystals exhibited nearly equal intensities of the red, green, and blue emissions upon 980 nm laser excitation. White light can be produced by adjusting the concentrations of the Ln3+ ions within the Y2O3 nanocrystals.

Active gold and palladium nanoparticles supported on a variety of oxides (CeO 2 , ZrO 2 , Al 2 O 3 , SiO 2 , MgO and ZnO) were synthesized using laser vaporization and microwave irradiation methods. The catalytic activities for CO oxidation on the nanoparticle catalysts were evaluated and compared among different oxide supports. The effect of shape on the catalytic activity is demonstrated by comparing the activities of the Au and Pd catalysts deposited on MgO nanocubes and ZnO nanobelts. The Au/ CeO 2 nanoparticles deposited on MgO nanocubes exhibit high catalytic activity and stability. The enhanced catalytic activity is attributed to the presence of a significant concentration of the corner and edge sites in MgO nanocubes. The Au-and Pd-doped Mn 2 O 3 nanoparticles show promising results for the low temperature CO oxidation. Several approaches for incorporating the Au and Pd nanocatalysts within mesoporous oxide supports are presented and discussed.

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Active gold and palladium nanoparticles supported on MgO nanocubes and ZnO nanobelts and transition-metal-containing MgO nanobelts were synthesized by combining evaporation and deposition-precipitation techniques. The high activity and stability of the Au/CeO2 and Pd/CeO2 nanoparticle catalysts deposited on the MgO cubes are remarkable and imply that a variety of efficient catalysts can be designed and tested using this approach. The significant increase in the concentration of corner and edge sites in MgO nanocubes make them well-defined supports to study the detailed mechanism of the catalytic activity enhancement.

Magnetic properties of sol-gel-prepared bulk samples of Co0.05Zn0.95O and Mn0.05Zn0.95O are reported before and after annealing in 5%H2∕95%Ar at 573 K for 6 h. The as-prepared samples are paramagnetic with the magnetic susceptibility χ following the Curie-Weiss law: χ=χ0+C∕(T−θ). The magnitudes of C are consistent with the magnetic moments expected for the Co2+ and Mn2+ states. After hydrogenation, the magnetism of Mn∕ZnO is unchanged but Co∕ZnO acquires room-temperature ferromagnetism (RTFM) with a magnetic moment of 0.35μB∕Co site and hysteresis loop with coercivity Hc≃600Oe, remanence Mr≃0.45emu∕g, and saturation magnetization Ms≃1.2emu∕g. Electron magnetic-resonance spectroscopy at 9.28 GHz gives signals corresponding to the Co2+ and Mn2+ states for the paramagnetic states and a broad FM signal for the hydrogenated Co∕ZnO. This difference under hydrogenation between Co∕ZnO and Mn∕ZnO suggests that n-type doping leads to stabilizing of RTFM in Co∕ZnO but not in Mn∕ZnO, the latter perhaps requiring p-type doping.