<p>We present a novel approach for the rapid synthesis of highly fluorescent carbon dots using a microwave-assisted reverse micelle (MARM) method. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) was used to form reverse micelles in a nonpolar medium, dodecane, which does not absorb microwave radiation. Reverse micelles containing an aqueous phase were dispersed in the oil phase, and these small polar droplets acted as nanoreactors. The aqueous phase contained citric acid and Tris base as reactants. Under microwave heating, only these microreactors absorbed microwave energy and were heated efficiently and homogeneously, facilitating the formation of carbon dots. The micelle size could be tuned by adjusting the water-to-surfactant molar ratio, producing carbon dots with uniform sizes ranging from 1.8 to 2.6&#xa0;nm, depending on the AOT concentration. Transmission electron microscopy and photospectroscopy data were compared for carbon dots prepared using hydrothermal, domestic microwave-assisted, solvothermal reverse micelle, hexanoic-acid-based MARM, and dodecane-based MARM approaches. The characteristics of carbon dots produced using the proposed method were similar to those obtained using hydrothermal and domestic microwave-assisted methods. However, the proposed method is faster than the hydrothermal process and yields more homogeneous carbon dots than the domestic microwave-assisted method, while maintaining a high quantum yield.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Synthesis of carbon dots via selective microwave heating of reverse micelles in a microwave-transparent solvent

  • Srikrishna Tummala,
  • Yen-Peng Ho

摘要

We present a novel approach for the rapid synthesis of highly fluorescent carbon dots using a microwave-assisted reverse micelle (MARM) method. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) was used to form reverse micelles in a nonpolar medium, dodecane, which does not absorb microwave radiation. Reverse micelles containing an aqueous phase were dispersed in the oil phase, and these small polar droplets acted as nanoreactors. The aqueous phase contained citric acid and Tris base as reactants. Under microwave heating, only these microreactors absorbed microwave energy and were heated efficiently and homogeneously, facilitating the formation of carbon dots. The micelle size could be tuned by adjusting the water-to-surfactant molar ratio, producing carbon dots with uniform sizes ranging from 1.8 to 2.6 nm, depending on the AOT concentration. Transmission electron microscopy and photospectroscopy data were compared for carbon dots prepared using hydrothermal, domestic microwave-assisted, solvothermal reverse micelle, hexanoic-acid-based MARM, and dodecane-based MARM approaches. The characteristics of carbon dots produced using the proposed method were similar to those obtained using hydrothermal and domestic microwave-assisted methods. However, the proposed method is faster than the hydrothermal process and yields more homogeneous carbon dots than the domestic microwave-assisted method, while maintaining a high quantum yield.