Synthesis Of Cobalt-based Hollow Nanomaterials, Characterization And Application

Hollow structure nano-materials have been given increasing attention due to their special structure and properties, and have become an effective functional material. Cobalt-based nano-material is an important material, and their synthesis and properties have attracted growing interests because of their prominent application in many fields. In this work, we have fabricated functional hollow cobalt-based nano-materials by using different methods and evaluated their performance in supercapacitor and gas sensing. The thesis explores the importance of the functional structure in the applications of energy and environment.A novel and stable layered cobalt nickel silicate hollow sphere compound was prepared for supercapacitor applications using a facile hydrothermal synthetic approach. The obtained material exhibited a good specific capacitance and outstanding long-term cycling stability (only 0.7% and 5% losses of its initial specific capacitance after 10000 and 20000 cycles, respectively) at a high current density of 20 A/g after annealing at 600 ℃. This work provides new insights of designing novel cobalt or nickel compounds for supercapacitor with excellent stability, and promotes the application of layered metal silicates as advanced supercapacitor materials.The Co3O4/CeO2 hollow nanocage composite was prepared for CO gas sensing application using ZIF-67 (MOF) as template by using a facile reflux method, which has a tunable interior structure from core-shell to hollow by simply adjusting the concentration of cerium nitrate. The obtained materials exhibited an outstanding gas sensing capacity to CO gas with a rapid response time (14 s) and a low detection limit (50 ppb). It also exhibited a higher response compared with Co3O4 and CeO2-The hollow structure had a substantial influence on the sensing performance (almost 2 times higher than the core-shell Co3O4/CeO2 and Co3O4/CeO2 after ball milling). This work provides a simple and efficient method of designing hollow structure compounds for gas sensing with a high sensitivity.