Preparation And Chemical Sensing Of Different Micro-structure Of Nickel Oxide And Photocatalytic Performance

Ultralong NiO nanowires assembled with NiO nanocrystals, NiO octahedrons, NiO spherical flowerlike structure assembled from NiO nanoflakes have been synthesized through hydrothermal, thermal decomposition. The role of different complexing agents in the information process of the NiO nanostructures with different morphologie has been investigated and the possible growth mechanisms have been proposed. In addition, the gas-sensing properties of ultralong NiO nanowires assembled with NiO nanocrystals, photocatalytic activity of NiO octahedrons and adsorption behaviors of NiO spherical flowerlike structure assembled from NiO nanoflakes were studied.(1) Synthesis and enhanced gas-sensing properties of ultralong NiO nanowires assembled with NiO nanocrystals:NiO crystallites based nanowires with different aspect ratios have been synthesized by a hydrothermal reaction of NiCl2 with Na2C2O4 and H2O in the presence of ethylene glycol (EG) and subsequent annealing at 400℃in air. Control over the aspect ratios of NiC2O4·2H2O precursor nanowires in the range of 11-1050 was achieved by adjusting the hydrothermal reaction temperature and time. The role of EG in the formation of NiC2O4-2H2O nanowires was investigated, the formation of the NiC2O4·2H2O nanowires results from the selective adsorption of EG molecules on (10-1), (-101), (010) and (0-10) prismatic faces of NiC2O4·2H2O with a monoclinic structure. The gas-sensing performance of the as-prepared NiO nanowires with different aspect ratios was investigated towards toluene, ethanol, acetone, triethylamine and methanol. It was found that the gas-sensing performance was improved with an increase on the aspect ratios of NiO nanowires.(2) Monodisperse Single-Crystalline NiO Octahedrons:Synthesis, Growth Mechanism and Size-dependent Photocatalytic Activity:NiO octahedrons have been synthesized by heating NiCl2 aqueous solution on the Si substrate at 400-500℃for 1 h. The average size of NiO octahedrons is increased by increasing the heating temperature. The NiO octahedrons have controllable sizes in the range of 165-250 nm. The role of Cl- in the formation of NiO octahedrons was investigated, the formation of the NiO octahedrons results from the selective adsorption of Cl- on unsaturated Ni sites of{111} surfaces of NiO nuclei with a cubic structure. The photocatalytic properties of the as-prepared NiO octahedrons obtained at different temperatures was investigated. The results suggest that the NiO octahedrons obtained at 400℃show a high catalytic activity for the degradation of acid naphtha red.(3) Synthesis of NiO spherical flowerlike structure assembled from NiO nanoflakes:NiO spherical flowerlike assembled from NiO nanoflakes have been synthesized by a hydrothermal reaction of Ni(NO3)2 with H2O in the presence of propanetriol and subsequent annealing at 400℃in air. The influence of reaction time on the products was investigated, and possible growth mechanisms have been proposed. The adsorptive activity of the as-prepared NiO spherical flowerlike structure assembled from NiO nanoflakes for the degradation of organic pollutants was investigated, the results suggest that NiO spherical flowerlike structure assembled from NiO nanoflakes show a high adsorptive activity.