Design And Synthesis Of Nickel Oxide Nanocrystals With Hierarchical Structures And Research On Their Performances

The nickel oxide (NiO) micro-nano materials with hierarchical structures are interesting advancedchemical materials, due to their extensive applications in many fields, such as dye absorption,photocatalysis, fuel cell, lithium-ion battery, dye-sensitized solar cells (DSSCs) and biomedicine etc. It isthe reason that the synthesis of NiO micro-nano materials has attracted much attention.Previous researchers have synthesized NiO micro-nano materials with various morphologies, such asnanoparticals, nanorods, nanowires, nanotubes, etc. However, the synthesis of the nickel oxide (NiO)micro-nano materials with hierarchical structures becomes an interesting research in the worldwide inrecent years. The hierarchical structures are built with smaller nanoparticles, nanofibers or nanoflakes,which possess more advantages, such as rich mesopores and large specific surface area. The nickel oxide(NiO) micro-nano materials with hierarchical structures possess potential application prospect in the fieldsof dye absorption, photocatalysis, fuel cell, lithium-ion battery, dye-sensitized solar cells (DSSCs) andbiomedicine etc. Therefore, the research on NiO nanomaterials with hierarchical structures has a broadapplication space.In this thesis, there is several major work as follows:(1) The synthesis of NiO were summarized briefly, and we introduced application in the fields of dyeabsorption, photocatalysis, lithium-ion battery etc.(2) Hierarchical NiO hollow microspheres with five different sizes have been synthesized by a simplerefluxing method. The sizes of the hierarchical NiO hollow microspheres can be facilely tuned by alteringthe sizes of functionalized polystyrene particles (PS) templates. Adsorption of Congo red (CR) onto theas-prepared five samples from aqueous solution was investigated. The results showed that the as-preparedNiO hollow microspheres were effective adsorbents for the removal of CR pollutant from waste water as aresult of their unique hierarchical structures and high specific surface areas. Moreover, the adsorptioncapacities for CR are different due to the different sizes of NiO hollow microspheres. It was observed thatthe adsorption capacity increased with the decrease of the size of hollow microspheres. Especially, thesmallest hierarchical NiO hollow microspheres have the highest adsorption capacity, which could achieve 526.3mg/g at room temperature (pH7.0). Most importantly, the adsorbent can be easily renewed, whichwill be a great potential material in real applications.(3) Flower-like Ni(OH)₂and NiO with hierarchical structures were synthesized by a template-andsurfactant-free, environmentally friendly chemical precipitation method. Adsorption of Congo red (CR)onto the as-prepared samples from aqueous solutions was investigated and discussed. The equilibriumadsorption data of CR on the as-prepared samples were analyzed by Langmuir models, suggesting that theLangmuir model provides the better correlation of the experimental data. The adsorption capacities forremoval of CR was determined using the Langmuir equation and found to be636.9mg/g and303mg/g forflower-like Ni(OH)₂and NiO, respectively. The as-prepared flower-like Ni(OH)₂and NiO show excellentadsorption capacities for Congo red pollutant from wastewater due to their hierarchical flower-likestructures and high specific surface areas.(4) Four different topographies NiO two dimensional films have been synthesized by differentmethods. Herein, cell viability on the four different topographies NiO two dimensional films has beendiscussed. Different cell growth rate has been analyzed by comparing hydrophilicity and surface roughnessof the four different topographies NiO two dimensional films. The result shows that small surfaceroughness is to the benefit of cell growth.The experimental results show that NiO micro-nanomaterials with hierarchical structure have betterdye adsorption performances. It is a reference for the preparation of advanced NiO micro-nanomaterialswith the high capability of dye adsorption in future. On the other hand, cell viability on the four differenttopographies NiO two dimensional films has been discussed. It will be a reference for cell viability of NiOmaterials. Moreover, these hierarchical NiO micro-nanomaterials and NiO films may have very goodapplication prospects in lithium-ion battery, fuel cell, dye-sensitized solar cells (DSSCs), CO catalysis,electroluminescence and gas sensitive materials domain.