Microstructure And Properties Of Carbon And Oxide Hollow Sphere Materials Synthesized By RF Templates

Resorcinol-formaldehyde (RF) was used as carbon precursor and templates to fabricate carbon hollow spheres, oxide hollow spheres and oxide/carbon composite microspheres. Further, the ITO/C one-dimensional composite nanotubes (nanowires) were synthesized by using RF as carbon precursor, indicating the controllability of RF in fabricating various structures of nanomaterials. The morphologies, microstructures and formation mechanism of the obtained samples were analysed by XRD, SEM, TEM, HRTEM, FT-IR and nitrogen absorption, etc. The influences of morphologies and microstructures of the carbon microspheres on the electrochemical properties were studied. The possibility and advantage of the carbon microspheres applied in supercapacitor and Li-ion battery were discussed. The application of ITO/C one-dimensional composite nanomaterials in gas sensor was discussed.It is the first time to synthesize the morphology-controlled RF carbon microspheres by inverse phase suspension method. The results indicated that the pH values, catalysts and surfactants are crucial in preparing the various RF carbon microspheres such as hollow spheres, bowl-like structures and microcapsules. The formation mechanism of RF carbon microspheres was proposed and the electrochemical properties were studied. The results showed that the RF carbon microspheres prepared with Na₂CO₃ as catalyst exhibited excellent capacity characters. The cyclic voltammetry revealed that the electrochemical properties of prepared carbon microspheres were stable, reversible and were available for charge/discharge under high current. The charge/discharge capacity and cyclic properties of RF carbon microcapsules prepared with K₂CO₃ as catalyst, as anode materials in Lithium-ion batteries, showed that the electrochemical property was stable with the efficiency of 99% and had a maximum value of 1059mAh/g.The intact metal oxide hollow microspheres with even particle size were synthesized by using surface-modified RF gel microspheres as templates. The mechansim of surface modification on RF gel microspheres by different surfactants were studied. The influences of surface modification on structure of metal oxide hollow microspheres were investigated. The ZnO/C composite microspheres were obtained by carbonization of Zn²⁺ loading RF composite microspheres. ZnO/C composite microspheres had stable cyclic voltammetry characters and faradic redox reaction effection, indicating that ZnO/C composite microspheres could be used as ideal supercapacitor materials.It is the first time to prepare ITO/C one-dimensional composite nanomaterials by using ITO and RF mixed solutions as composite precursors. The influence of ITO concentration on the structure of ITO/C one-dimensional nanocomposites was discussed. The results showed that ITO nanoparticles could be well dispersed in RF carbon gel networks by using ITO and RF composite sol-gel precursors. The H2 gas sensitivity indicated that the prepared ITO/C one-dimensional nanocomposites exhibited high sensibility and low response time.The intact carbohydrate microspheres were prepared by hydrothermal reaction of glucose solution. The morphologies and microstructures of carbohydrate microspheres could be tailored with addition of different additives. The various oxide hollow microspheres were prepared by using the obtained carbohydrate microspheres as templates. The zinc/carbon composite precursor microspheres were obtained by hydrothermal process of ZnCl2/RF/glucose system. ZnO hollow microspheres with various morphologies were formed by controlling the thermal treatment conditions during removal of carbon templates. The study provides background for application of RF in the fields of hydrothermal strategy and glucose.