《厦门大学学报（自然科学版）》

将富勒烯C60和C70分别在空气气氛中350 ℃下煅烧,然后采用尿素还原法在温和(90 ℃)条件下制备得到碳量子点; 以透射电子显微镜、粉末X-射线衍射、拉曼光谱和傅里叶变换红外光谱等对碳量子点的组成和形貌进行表征,通过紫外-可见吸收光谱和荧光光谱对其光学性能进行研究; 并推测碳量子点的形成机制.结果表明,在激发光波长为320 nm时,两种碳量子点的荧光最大发射峰波长位于450 nm附近,相对荧光量子产率分别为23.24%和27.55%,推测其形成机制为尿素对空气气氛中煅烧过的富勒烯表面氧化位点的还原.该结果为温和条件下合成碳量子点提供了一种新的思路.

Carbon quantum dots(CQDs)exhibit excellent photoluminescent property and environmental friendliness.In this work,fullerene C60 and C70were treated at 350 ℃ in muffle furnace under air condition,followed by the reduction of urea at 90 ℃ to prepare CQDs.The chemical composition and structure of CQDs were characterized using transmission electron microscope,powder X-ray diffraction,Raman spectroscopy and Fourier transform infrared spectroscopy.The optical properties of CQDs were studied using ultraviolet-visible absorption spectrometry and photoluminescence spectroscopy.The results showed that the emission wavelength was around 450 nm under the excitation wavelength of 320 nm and the relative quantum yield of C60-CQDs and C70-CQDs were 23.24% and 27.55%,respectively.Our studies revealed a possible mechanism of the reduction of oxygen defects on the calcined fullerene.This work proposed a new method for the synthesis of CQDs under mild conditions.

引言
1 实验部分
2 结果与讨论
3 结论

图1 C60-CQDs(a)和C70-CQDs(b)的TEM图和粒径分布<br/>Fig.1 TEM images and size distributions of C60-CQDs(a)and C70-CQDs(b)

图1 C60-CQDs(a)和C70-CQDs(b)的TEM图和粒径分布
Fig.1 TEM images and size distributions of C60-CQDs(a)and C70-CQDs(b)

图2 C60(a)和C70(b)及其各反应步骤产物的XRD谱图<br/>Fig.2 XRD patterns of C60(a), C70(b)and products at various reaction stages

图2 C60(a)和C70(b)及其各反应步骤产物的XRD谱图
Fig.2 XRD patterns of C60(a), C70(b)and products at various reaction stages

图3 C60(a)和C70(b)及其各反应步骤产物的Raman谱图<br/>Fig.3 Raman spectra of C60(a), C70(b)and products at various reaction stages

图3 C60(a)和C70(b)及其各反应步骤产物的Raman谱图
Fig.3 Raman spectra of C60(a), C70(b)and products at various reaction stages

图4 C60(a)和C70(b)及其各反应步骤产物的FTIR谱图<br/>Fig.4 FTIR spectra of C60(a), C70(b)and products at various reaction stages

图4 C60(a)和C70(b)及其各反应步骤产物的FTIR谱图
Fig.4 FTIR spectra of C60(a), C70(b)and products at various reaction stages

图5 C60-CQDs(a)和C70-CQDs(b)的UV-Vis吸收光谱图和PL发射光谱图<br/>Fig.5 UV-Vis and PL spectra of C60-CQDs(a)and C70-CQDs(b)

图5 C60-CQDs(a)和C70-CQDs(b)的UV-Vis吸收光谱图和PL发射光谱图
Fig.5 UV-Vis and PL spectra of C60-CQDs(a)and C70-CQDs(b)

图6 不同激发波长下C60-CQDs(a)和C70-CQDs(b)的PL发射光谱图<br/>Fig.6 PL spectra of C60-CQDs(a)and C70-CQDs(b)at different excitation wavelength

图6 不同激发波长下C60-CQDs(a)和C70-CQDs(b)的PL发射光谱图
Fig.6 PL spectra of C60-CQDs(a)and C70-CQDs(b)at different excitation wavelength

[1] KRÄETSCHMER W,LAMB L D,FOSTIROPOULOS K,et al.Solid C60:a new form of carbon[J].Nature,1990,347(6291):354-358.
[2] IIJIMA S.Helical microtubules of graphitic carbon[J].Nature,1991,354(6348):56-58.
[3] GEIM A K,NOVOSELOV K S.The rise of graphene[J].Nature Materials,2007,6(3):183-191.
[4] XU X Y,RAY R,GU Y L,et al.Electrophoretic analysis and purification of fluorescent single-walled carbon nano-tube fragments[J].Journal of the American Chemical Society,2004,126(40):12736-12737.
[5] SUN Y P,ZHOU B,LIN Y,et al.Quantum-sized carbon dots for bright and colorful photoluminescence[J].Journal of the American Chemical Society,2006,128(24):7756-7757.
[6] BOTTINI M,BALASUBRAMANIAN C,DAWSON M I,et al.Isolation and characterization of fluorescent nanoparticles from pristine and oxidized electric arc-produced single-walled carbon nanotubes[J].The Journal of Physical Chemistry B,2006,110(2):831-836.
[7] NGUYEN V,SI J H,YAN L H,et al.Electron-hole recombination dynamics in carbon nanodots[J].Carbon,2015,95:659-663.
[8] LEE J,KIM K,PARK W I,et al.Uniform graphene quantum dots patterned from self-assembled silica nanodots[J].Nano Letters,2012,12(12):6078-6083.
[9] YU H W,LI X Y,ZENG X Y,et al.Preparation of carbon dots by non-focusing pulsed laser irradiation in toluene[J].Chemical Communications,2016,52(4):819-822.
[10] YAN X,CUI X,LI L S.Synthesis of large,stable colloidal graphene quantum dots with tunable size[J]. Journal of the American Chemical Society,2010,132(17):5944-5945.
[11] WU X,TIAN F,WANG W X,et al.Fabrication of highly fluorescent graphene quantum dots using L-glutamicacid for in vitro/in vivo imaging and sensing[J].Journal of Materials Chemistry C,2013,1(31):4676-4684.
[12] JIA X F,LI J,WANG E K.One-pot green synthesis of optically pH-sensitive carbon dots with upconversion luminescence[J].Nanoscale,2012,4(18):5572-5575.
[13] JIANG J,HE Y,LI S Y,et al.Amino acids as the source for producing carbon nanodots: microwave assisted one-step synthesis, intrinsic photoluminescence property and intense chemiluminescence enhancement[J].Chemical Communications,2012,48(77):9634-9636.
[14] ZHANG Q H,SUN X F,RUAN H,et,al.Production of yellow-emitting carbon quantum dots from fullerene carbon soot[J].Science China Materials,2017,60(2):141-150.
[15] CIOTTA E,PAOLONI S,RICHETTA M,et al.Sensitivity to heavy-metal ions of unfolded fullerene quantum dots[J].Sensors,2017,17(11):2614-2629.
[16] CHEN G X,WU S L,HUI L W,et al.Assembling carbon quantum dots to a layered carbon for high-density supercapacitor electrodes[J].Scientific Reports,2016,6:19028-19037.
[17] HUMMERS W S,JR,OFFEMAN R E.Preparation of graphitic oxide[J].Journal of the American Chemical Society,1958,80(6):1339-1339.
[18] HARE J P,DENNIS T J,KROTO H W.The IR spectra of fullerene-60 and -70[J].Journal of Chemical Society,Chemical Communication,1991(6):412-413.
[19] HOLÁ K,SUDOLSKÁ M,KALYTCHUK S,et al.Graphitic nitrogen triggers red fluorescence in carbon dots[J].ACS Nano,2017,11(12):12402-12410.
[20] SUN L,WANG L,TIAN C G,et al.Nitrogen-doped graphene with high nitrogen level via a one-step hydrothermal reaction of graphene oxide with urea for superior capacitive energy storage[J].RSC Advances,2012,2(10):4498-4506.

备注

引言

1 实验部分

2 结果与讨论

3 结论

学报简介

备注

引言

1 实验部分

2 结果与讨论

3 结 论

学报简介

3 结论