posted on 2021-08-26, 07:32authored byJianliang Bai, Guojun Yuan, Yaqing Zhu, Zhujun Huang, Lu Zhang, Xinyu Wang, Shuang Wu, Lili Ren
Fluorescent
carbon dots (CDs) have attracted growing attention
and have exhibited widespread potential applications in photocatalysis,
bioimaging, and optoelectronics in recent years. However, due to the
complex structure of CDs, both the molecular ingredients and the intrinsic
mechanisms governing the fluorescence (FL) of CDs are poorly understood.
Herein, dual-emission N-doped carbon dots (N-CDs) were synthesized
through the solvothermal reaction of p-phenylenediamine
and folic acid in deionized water. Interestingly enough, the second
emission band of N-CDs can be tuned by changing the polarity of the
solvent, showing an obvious solvent dependence. The first emission
band has obvious excitation-wavelength dependence, while the second
emission band does not. The first emission band likely comes from
diversified amide units, while the homogeneous polymers chains are
the most likely origin of the second emission band. These findings
greatly improve our understanding of the FL origin of CDs and help
to guide future preparations of novel nanomaterials.