Nickel hydroxide has received increased attention especially due to its electrochemical properties and potential applications in rechargeable Ni-base alkaline batteries, e.g., Ni/Cd, Ni/Zn, and Ni/MH. Ni(OH)2 has a hexagonal layered structure with two polymorphs, α- and β-Ni(OH)2. α-Ni(OH)2 shows superior electrochemical properties compared to those of the β-form. Nanosized flowerlike α-nickel hydroxide materials with an interlayer spacing of 7.0 Å have been prepared by a microwave-assisted hydrothermal method. The experimental results from XRD and FT-IR showed that the Ni(OH)2 sample prepared by this method had the typical α-phase. FE-SEM images showed many uniform flowerlike architectures with diameters of 700 nm−1µm which consisted of the aggregated flakes. TEM results showed the flakes were built up from many nanocrystals with 2–3 nm diameters. TGA and TPD were employed to investigate thermal stability and gas evolution during the heating process. α-Nickel hydroxide was transferred to NiO with a cubic crystalline structure after being calcined at 450 °C; the NiO still kept the morphology of α-Ni(OH)2. Cyclic voltammetry was used to determine the electrochemical properties of the Ni(OH)2 electrode in 1 M KOH. α-Ni(OH)2 prepared by MW-HT had the best electrochemical activity for the electrochemical reduction of O2 compared with α-Ni(OH)2 synthesized by conventional HT methods and β-Ni(OH)2. The effects of nickel sources and precipitators on the phase and morphology of the products were studied. Conventional hydrothermal methods were used to study the role of microwave irradiation. The possible growth mechanism is discussed here. The CV experiments showed that H2O2 can be reduced to OH− on the α-Ni(OH)2 electrode. The Levich equation was used to calculate the number of electrons transferred during the O2 redox reaction.

ZnO materials with a range of different morphologies have been synthesized via a simple solvothermal method with different solvents. Zinc acetylacetonate was used as the zinc source in such solvothermal syntheses for the first time. XRD data showed that single-phase ZnO with the wurtzite crystal structure was obtained for all the solvents used. FE-SEM imaging showed that ZnO with cauliflower-like, truncated hexagonal conical, tubular and rodlike, hourglass-like, nanorods, and spherical shapes were produced when THF, decane, water, toluene, ethanol, and acetone were used as the solvent, respectively. The TEM data showed that the crystalline ZnO had different growth habits in the different solvents. The optical properties of the as-prepared ZnO materials were investigated by UV-vis absorption and room temperature photoluminescence. Photodegradation of phenol was used as a model reaction to test the photocatalytic activity of the ZnO samples. ZnO samples with different morphologies and crystal growth habits exhibited different activities to phenol degradation. The ZnO material prepared using THF as the solvent showed a nine-times enhancement of the kinetic rate constants over commercial ZnO (0.1496 min -1 vs 0.0182 min -1 ). The influence of the solvents on the morphology of ZnO samples and the effect of the morphologies on the photocatalytic activity are discussed.

Self-assembled multidoped cryptomelane hollow microspheres with ultrafi ne particles in the size range of 4-6 nm, and with a very high surface area of 380 m 2 g − 1 have been synthesized. The particle size, morphology, and the surface area of these materials are readily controlled via multiple framework substitutions. The X-ray diffraction and transmission electron microscopy (TEM) results indicate that the as-synthesized multidoped OMS-2 materials are pristine and crystalline, with no segregated metal oxide impurities. These results are corroborated by infrared (IR) and Raman spectroscopy data, which show no segregated amorphous and/or crystalline metal impurities. The fi eld-emission scanning electron microscopy (FESEM) studies confi rm the homogeneous morphology consisting of microspheres that are hollow and constructed by the self-assembly of pseudo-fl akes, whereas energy-dispersive X-ray (EDX) analyses imply that all four metal cations are incorporated into the OMS-2 structure. On the other hand, thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) demonstrate that the as-synthesized multidoped OMS-2 hollow microspheres are more thermally unstable than their single-doped and undoped counterparts. However, the in-situ XRD studies show that the cryptomelane phase of the multidoped OMS-2 hollow microspheres is stable up to about 450 ° C in air. The catalytic activity of these microspheres towards the oxidation of diphenylmethanol is excellent compared to that of undoped OMS-2 materials.

CuO is an important transition metal oxide with a narrow bandgap (E g ) 1.2 eV). CuO has been used as a catalyst, a gas sensor, in anode materials for Li ion batteries. CuO has also been used to prepare high temperature superconductors and magnetoresistance materials. In this paper, CuO with urchin-like morphologies has been synthesized via a simple reflux method. The reflux method has advantages over other solution-based techniques, such as ease of operation, safety, and high yield (95%). XRD results showed pure tenorite CuO was produced. FE-SEM exhibited an urchin-like morphology of CuO, which is composed of aggregates of nanosized strips. HR-TEM showed that the strips were single crystals with the lattice fringe of 2.3 Å, which corresponds to (111). DSC and TGA results suggested that as-synthesized CuO had high thermal stability. Time-dependent experiments were conducted to illustrate the evolution of the urchin-like morphology and crystal phase formation of CuO. The effects of copper sources and precipitators on the phase and morphology of the products were studied. As-synthesized CuO showed much better catalytic performance, increased yield (from 64.3% to 89.5%) for olefin epoxidation than commercial CuO and CuO prepared by thermal decomposition of copper hydroxide.