One-pot synthesis of photoluminescent carbon dots by carbonization of cyclodextrin and their application in Ag+ detection Meng Hu, Yu Yang, Xiaoyu Gu, Yang Hu, Jian Huang, and Chaoyang Wang1
Table S1. Fluorescence quantum yield and product yield of C-dots from different carbohydrates. Samples -Cyclodextrin Fructose Glucose Citrate
Quantum yield 13.5% 11.5% 7.5% －
Yield 34% 8% 13% －
Table S2. The yield of C-dots from -cyclodextrin at different temperatures Temperature (oC) Yield (%) .
50 0
60 16
70 34
80 23
90 11
50 oC
60 oC
70 oC
80 oC
90 oC
Figure. S1. Photographs of solutions with -cyclodextrin (2 g), hydrochloric acid (15 mL, 36-38 wt.%) and deionized water (15 mL) at different temperatures for 4 h.
Figure. S2. Carbon spheres formed by further dehydration and aggregation of C-dots.
a
40
Percentage (%)
c 30
20
10
0 1.5
2.0
2.5
3.0
3.5
4.0
Size (nm)
b
40
Percentage (%)
d 30
20
10
0 1.5
2.0
2.5
3.0
3.5
Size (nm)
Figure. S3. (a,b) TEM images and (c,d) size histograms (counting 100 particles at least) of C-dots synthesized from and -cyclodextrins, respectively. Scale bars in a,b: 20 nm..
4.0
Intensiy (a.u.)
a
b
c
20
40
60
80
2 (Degree) Figure. S4. (a-c) XRD patterns of C-dots synthesized from , and -cyclodextrins, respectively.
Transmittance (%)
a
b
2926 3416
C-H
c
1643 1418
C=O
850 765
C-O1028
O-H
C-H
C-O
4000 3500 3000 2500 2000 1500 1000
500
Wavelength (cm-1) Figure. S5. (a-c) FT-IR spectra of C-dots synthesized from , and -cyclodextrins, respectively.
500
Counts
400
a b c
300 200 100 0
5
10
15
20
25
30
Time (ns) Figure. S6. (a-c) Fluorescence decay profiles of C-dots synthesized from , and -cyclodextrins, respectively.
a
30 min under sunlight
c
b
d 12 h in dark
Figure. S7. (a, b) Photographs of C-dots (200 mg/L) and AgNO3 (200 M) mixture before and after reaction under sunlight for 30 min. (c,d) Photographs of C-dots (200 mg/L) and AgNO3 (200 M) mixture before and after reaction in dark for 12h.
PL Intensity (a.u.)
200
[Ag+] (M) 0 1 10 25 50
160 120 80 40 0
500
550
600
650
Wavelength (nm) Figure. S8. Representative FL emission spectra of aqueous solutions of C-dots (100 mg/L) and AgNO3 with different concentrations (0-25 M) after 30 min under sunlight.
e h sunlight
PL intensity strengthen Low concentration of Ag+
Ag e h PL intensity weaken
C-dot
Ag0
High concentration of Ag+
Figure. S9. Schematic representation of reduction of Ag+ to Ag0 by C-dots under sunlight.
50
a
b
40
Volume (%)
Volume (%)
40
50
30 20 10
30 20 10
0 -1 10
0
10
1
10
2
10
0 -1 10
3
10
0
10
Size (nm) 50
c
20 10
3
2
10
30 20 10
0 -1 10
0
10
1
10
2
10
0 -1 10
3
10
0
10
1
10
3
10
Size (nm)
Size (nm) 50
100
e
80
Size (nm)
Volume (%)
10
d
40
30
40
2
10
50
Volume (%)
Volume (%)
40
1
10
Size (nm)
30 20
f
60 40 20
10 0
0 -1 10
0
10
1
10
Size (nm)
2
10
3
10
0
100
200
300
400
500
[Ag+] (mM)
Figure. S10. Size distribution of C-dots (100 mg/L) with different concentrations of AgNO3 after 30 min under sunlight: (a) 1, (b) 10, (c) 25, (d) 50, (e) 500 M. (f) The relationship between the average particle size and AgNO3 concentration.
