Preparation Of Metallic Oxide Micro/nanomaterials By Biotemplates And The Investigation Of Their Properties

There are some problems existing on the nanofabrication techniques,such as excessive reliance on advanced and expensive large instruments,and poor controllability of the fabricated micro/nanomaterials,which cannot meet the requirements of mass production and obtain specific morphologies and structures effectively.In order to solve these problems,scientists are beginning to pay attention to the colorful living system.They have used biological materials as templates to fabricate some elaborate micro/nanomaterials.It is important to discover economic,easy-to-get and sophisticated biological materials,and develop simple,eco-friendly and efficient synthetic methods.In numerous biological materials,plants are widely distributed in the nature,which are born with all kinds of complicated and delicate morphologies and structures.The characteristics of plants,such as eco-friendly,renewable and easy-to-get,attracted the attention of scientists.In this dissertation,we discovered a kind of new biotemplates and committed to developing easy and efficient preparation methods.We discussed the preparation process and the mechanism of every biotemplate and the corresponding preparation method in detail.Furthermore,we also systematically tested the performances of the fabricated materials.The main work and results are shown as follows:(1)A brand-new biotemplate namely root hairs of Syngonium podophyllum is used to fabricate hollow double-layer CuO microtubes by “one-step” activation and electroless deposition.Morphologies,compositions and microstructures of the as-prepared samples were characterized by a series of techniques.The original morphology was well preserved and the thickness of tubular wall could be adjusted in a one-step method by controlling the time of electroless deposition.We systematically studied the fabrication process and the mechanism of the CuO microtubes.Furthermore,the hollow double-layer CuO microtubes exhibited good gas sensing performance toward IPA,which was attributed to their large surface areas.It suggests the resulted CuO microtubes have the potential applications for gas sensors.(2)We fabricated porous hollow ZnO-CeO2_ composite microspheres and Zn O microspheres using rape pollen grains as biotemplates.Pollen grains are born with porous structures,economic and easy-to-get features,which provide a simple and efficient way to fabricate porous hollow structures.We confirmed the obtained samples were ZnO-CeO2_ composite microspheres and ZnO microspheres by analyzing morphologies,compositions and microstructures.We investigated the photocatalytic performances of ZnO-CeO2_ composite microspheres and single Zn O microshperes,and found that the photocatalyticity of the ZnO-CeO2_ composite microspheres was superior than that of single ZnO microshperes.The results indicated doping specific semiconductor materials would effectively enhance the photocatalytic performances of the samples.Finally,we also discussed the photocatalytic mechanism of the ZnO-CeO2_ composite microspheres in details.(3)We used cotton as biotemplates to fabricate unique helical band-like SnO2_ microfilaments by a simple sol-gel method.It is a simple,efficient and eco-friendly preparation method,which use only two kinds of chemical reagents(SnCl2 and HCl).We studied the preparation process and the mechanism of the SnO2_ microfilaments,and explained the reasons of the formation of helical ribbon structures on the basis of plant cytology.Furthermore,the spiral SnO2_ microfilaments exhibited good gas sensing performance toward ethanol,which was attributed to their large surface areas.The recovery time could be up to 4 s when the concentration of ethanol gas was 100 ppm.It suggests the resulted SnO2_ microfilaments have the potential applications for gas sensors.