【摘要】 以乙酰丙酮钴为原料,采用单步金属有机物化学气相沉积法,在600~800℃温度下制备碳包覆钴的核/壳结构Co/C纳米颗粒。利用X射线衍射、透射电镜和Raman光谱仪等对合成产物的元素组成和结构进行表征,研究合成温度对产物形貌和结构的影响,分析Co/C核/壳纳米颗粒的形成机理,并通过差式扫描量热分析/热重分析研究产物的热稳定性。结果表明,不同反应温度下的产物中,Co核的粒径均在10~60 nm之间,C壳层的厚度在10~20 nm之间。随合成温度从600℃升至800℃,Co核由HCP和FCC的混合结构逐步转变为单一的FCC结构,而C层的结晶度逐渐升高。核/壳结构Co/C纳米颗粒在空气气氛下从250℃开始缓慢氧化,结晶度高的C壳层对Co核具有更好的保护作用。更多还原

【Abstract】 Co/C core/shell nanoparticles were synthesized at 600-800 ℃ by one-step metal organic chemical vapor deposition using Co(acac)3 as precursor. XRD, TEM and Raman analyses were used to characterize the elemental composition and microstructure of the products. The effects of temperature on morphology and microstructure of Co/C core/shell nanoparticles were studied. The formation mechanism of Co/C shell/core nanoparticles was also explored. In addition, thermal stability was analyzed by DSC-TG test. The results show that the as-obtained core/shell nanoparticles have a core size ranging from 10 to 60 nm and a shell thickness from 10 to 20 nm. As the reaction temperature increases from 600 to 800 ℃, the Co cores transform from the mixture of HCP phase and FCC phase to pure FCC phase, and the crystallinity degree of the C shells increases gradually. The oxidization of Co/C core/shell nanoparticles occurs at 250 ℃in atomosphere, and the C shells with a higher crystallinity degree can prevent the Co core from oxidization more effectively.更多还原