& 7klv 6 emitting and size tunability 1 functionalized ... · s-1 1 supporting information 2 3...
TRANSCRIPT
S-1
1 Supporting Information
2
3 Controllable ionic liquid-assisted electrochemical exfoliate
4 carbon fibers for the green and large-scale preparation of
5 functionalized graphene quantum dots endowed with multicolor
6 emitting and size tunability
7 Yuting Yana, Henan Lib, Qirui Wanga, Hanping Maoa, Wang Kun*a,b
8 aKey Laboratory of Modern Agriculture Equipment and Technology, Institute of
9 Agricultural Engineering, Jiangsu University, Zhenjiang, 212013, P.R. China
10 bSchool of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang,
11 212013, P. R. China.
12
13 Corresponding author. Tel.: +86 511 88791800; fax: +86 511 88791708. 14 E–mail address: [email protected]; [email protected]
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C.This journal is © The Royal Society of Chemistry 2017
S-2
1 Fig. S1
2
3
4
5 Fig. S1. Time evolution of ILs electrolyte and carbon fiber anode during exfoliation in
6 [Bmim][BF4] electrolyte in different stages (A: before exfoliation; B: the beginning of
7 exfoliation; C: an hour in exfoliation; D: the end of exfoliation).
A B
D C
S-3
1 Quantum Yields (QYs) Measurements
2 The quantum yields of as-prepared G-GQDs were measured and calculated by
3 using a comparative method (Table S1). Rhodamine B in water (QYs=0.31) was
4 chosen as the standard fluorophore with excitation at 340 nm as the reference. And the
5 quantum yields of the GQDs were calculated according to:
6
2R
R 2R R
AI nI A n
7 Where Φ, I, n and A designates the quantum yield, measured integrated emission
8 intensity, refractive index and the optical absorbance, respectively. The subscript "R"
9 refers to standard with known quantum yield.
10 Table S1. QYs of the as-prepared G-GQDs
Sample Integrated
emissions
intensity (I)
Abs. at 340
nm (A)
Refractive
index of
solvent (n)
Quantum yield
(Φ)
Rhodamine B 19568 0.017 1.33 0.31 (known)
G-GQDs 13412 0.042 1.33 0.086
11 In addition, with the assistance of ionic liquid, G-GQDs with a quantum yield up to
12 8.6% are successfully prepared via electrochemical exfoliate, which is higher than that
13 of the hydrothermal cleaving routes (< 8%).1,2
S-4
1 Characterization of the CFs
2 Raman spectroscopy is considered to be a powerful and efficient technique for
3 characterizing the carbonization and graphitization on carbon-based materials.3 The
4 D- and G-band (ID/IG) ratio of Raman spectra is a parameter to estimate the disorder
5 degree and the sp2 domains. Thus, the Raman spectrum of starting material (CFs) as
6 showed in Fig. S2A. The characteristic peaks at around 1359 cm1 (D-band) and 1589
7 cm1 (G-band), corresponding to the sp3 hybridized and the sp2 hybridized,
8 respectively. Form the Raman spectra, it was observed that the small domain structure
9 of the sp2 in original CFs (Integrated intensity), which is beneficial to get size
10 controlled synthesis of GQDs in accordance with Peng’s report.4 Meanwhile, the
11 higher ratio of ID/IG (Integrated intensity) on original CFs indicated that the existence
12 of non-graphitized structure in original CFs.5,6
13 Further, XRD tool was employed to study the crystalline structure of the original
14 CFs presented in Fig. S2B. There is an obvious diffraction peak at ∼25.0° can be
15 observed in the spectrum, corresponding to the (002) diffraction of graphitic
16 structures, the absence of the (110) band at ∼44.0°even indicates a non-graphitized
17 carbonaceous structure in original CFs.7
18 Combined with the analysis of Raman and XRD, it is clearly confirmed that CFs
19 were possessed with carbonized structure. Such a carbonized CFs can be easily
20 broken down, leading to the creation of GQDs with different size distribution in
21 scalable amounts.
22
S-5
1 Fig. S2
2
10 20 30 40 50 60 70 80
Inte
nsity
/ a.
u.
2 Theta / degree
B
500 1000 1500 2000 2500
17933.5
G
In
tens
ity /
a.u.
Raman shift / cm-1
DA
51727.3
3 Fig. S2. Raman spectra (A) and XRD pattern (B) of original CFs.
S-6
1 Fig. S3
2
3500 3000 2500 2000 1500 1000
b
17421421
15501638
Tr
ansm
ittan
ce
Wavenumber / cm-1
3450
a
A
800 700 600 500 400 300 200 100
O 1s
C 1s
aInte
nsity
/ a.
u.
Binding energy / eV
b
B
3 Fig. S3. (A) FTIR and (B) XPS spectra of G-GQDs (a) and Y-GQDs (b) were
4 synthesized with ratios of H2O/ILs at 15% and 30% as electrolyte, respectively.
S-7
1 Fig. S4
2
300 400 500 600 700
PL
Inte
nsity
(a.u
)
Wavelength / nm
350nm 370nm 390nm 410nm 430nm 450nm 470nmB-GQDs
A
400 500 600 700
PL In
tens
ity(a
.u)
Wavelength / nm
420nm 430nm 440nm 450nm 460nm 470nm 480nm 490nmG-GQDs
B
450 500 550 600 650 700
PL In
tens
ity(a
.u)
Wavelength / nm
470nm 480nm 490nm 500nm 510nm 520nm 530nmY-GQDs
C
3 Fig. S4. The PL spectra of the (A) B-GQDs, (B) G-GQDs and (C) Y-GQDs aqueous
4 solution excited by various wavelengths, respectively.
S-8
1 The effect of the water on the electrochemical properties of ILs
2 In order to investigate the influence of the water on the electrochemical properties
3 of ILs, the cyclic voltammetrys (CVs) recorded in ILs contain different content of
4 H2O, as shown in Fig. S5. It is seen that the electrochemical potential window of the
5 IL/water was decreased with the content of water from 0 vt % H2O to 30 vt % H2O
6 (Fig. S5A). Thus, we can infer that the trend of decreasing activation voltages with
7 increasing water content is correlated to the smaller over potential required for the
8 electrochemical oxidation of water. As such, hydroxyl radicals released from the
9 oxidation of water may play an important role. Meanwhile, the viscosity of ILs may
10 be changed by other means such as stirring, so we also investigate the effect of
11 stirring on viscosity of ILs by CV test. However, there is no any change on
12 electrochemical potential window of pure ILs before and after stirring from CV
13 curves (Fig. S5B).
S-9
1 Fig. S5
2
-2 -1 0 1 2 33
2
1
0
-1
-2
-3
-4
E1
E2
cb
Cu
rren
t /
A
Potential / V
a
E3
A
-2 -1 0 1 2 31.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
Curr
ent /
A
Potential / V
before stirring after stirring
B
3 Fig. S5. (A) CVs curve recorded in different electrolyte with volume ratio of H2O/ILs
4 at (a) 0%, (b) 15% and (c) 30%, respectively; (B) CVs curve recorded in pure ILs
5 before and after stirring.
S-10
1 Fig. S6
2
0.0 0.3 0.6 0.9 1.2 1.5
0
700
1400
2100
2800
3500
ba
ECL
Inte
nsity
/ a.
u.Potential / V
cB
0.0 0.3 0.6 0.9 1.2 1.5
0.00
0.04
0.08
0.12
0.16 cb
Curr
ent /
mA
Potential / V
a
A
3 Fig. S6. (A) CV and (B) ECL-potential curves of (a) G-GQDs/Ru(bpy)32+, (b) G-
4 GQDs/Ru(bpy)32+ and (c) B-GQDs/ Ru(bpy)3
2+ in 0.1 M pH 9.0 PBS.
S-11
1 Fig. S7
2
0
800
1600
2400
3200
4000
pH 11
pH 10
pH 9
pH 8
pH 7
ECL
Inte
nsity
/ a.
u.
Time
pH 6
3 Fig. S7. ECL-potential curves of the B-GQDs/Ru(bpy)32+ in PBS with different pH
4 values.
S-12
1 Fig. S8
2
0
3000
6000
9000
12000
15000
18000
0.0 0.5 1.0 1.5 2.0 2.5 3.02.4
2.8
3.2
3.6
4.0
4.4
Log
[ECL
Inte
nsity
/ a.
u.]
Log [Ru(bpy)32+/ M]
1000M
200M
100M
50M30M
16M6M
ECL
Inte
nsity
/ a.
u.
Time
2M
A
0
2000
4000
6000
8000
I
ECL
Inte
nsity
/ a.
u.
Time
B
I
I
3 Fig. S8. (A) ECL-potential curves of the B-GQDs/Ru(bpy)32+ in PBS (pH 9.0) with
4 different Ru(bpy)32+ concentration, inset: Calibration curve for Ru(bpy)3
2+; (B) Effect
5 of Ru(bpy)32+ concentration on the change of ECL intensity with PCP.
S-13
1 Selectivity, reproducibility and stability of the ECL senseing
2 Further, the long-term stability of the as-constructed ECL sensor was investigated
3 during 25 days by measuring the ECL response upon of B-GQDs/Ru(bpy)32+ system
4 in 0.1 M PBS (pH 9.0) with adding 50 pg mL−1 PCP (Fig.S9A). In a series of five
5 electrodes prepared in the same way, a relative standard deviation (RSD) of 4.5% was
6 obtained, indicating the reliability of the 25 days.
7 In addition, the specifity of this ECL sensor was studied using 3-chlorophenol (3-
8 CP), 2,4,6-trichlorophenol (1,3,5-TCP), and 2,4-dichlorophenol (2,4-DCP) as
9 inerferents. As shown in Fig. S9B, only PCP enhanced the ECL emission of B-
10 GQDs/Ru(bpy)32+ system dramatically, whereas the analogs of PCP changed the ECL
11 emission slightly (e.g., 3-CP, 1,3,5-TCP, 2,4-DCP). The reason might be attributed to
12 that the above interferents possess more stable chemical properties, which did not
13 make a better facilitate effect to electrochemical reaction of Ru(bpy)32+.
S-14
1 Fig. S9
2
0
2000
4000
6000
8000
10000
DNPTCP
DCPPCP
Blank
ECL
Inte
nsity
/ a.
u.
B
0 5 10 15 20 250
3000
6000
9000
12000
ECL
Inte
nsity
/ a.
u.
Time / day
A
3 Fig. S9. (A) Stability of the ECL sensor over 25 days in 0.1 mol L1 PBS (pH 9.0)
4 with 50 pg mL−1 PCP; (B) ECL of 10 pg mL−1 DCP, TCP, DNP and PCP on the
5 responses of the sensor in 0.1 mol L1 PBS (pH 9.0).
S-15
1 Table S2 Comparison of other ECL systems for determination of PCP
Materials Linear range Detection limit Ref.
GQDs-CdS NCs 0.01 ~ 500 ng mL−1 3 pg mL−1 [8]
CuO NWs/rGO 0.027 ~ 266.3 ng mL−1 9 pg mL−1 [9]
MWCNTs@GONR
s0.002 ~ 10 ng mL−1 0.7 pg mL−1 [10]
B-GQDs 0.02 ~ 150 pg mL-1 6.7 fg mL-1 this work
S-16
1 Notes and references
2 1 D. Y. Pan, J. C. Zhang, Z. Li and M. H. Wu, Adv. Mater., 2010, 22, 734–738.
3 2 J. H. Shen, Y. H. Zhu, C. Chen, X. L. Yang and C. Z. Li, Chem. Commun., 2011, 47,
4 2580–2582.
5 3 C. Gomez-Navarro, R. T. Weitz, A. M. Bittner, M. Scolari, A. Mews, M. Burghard
6 and K. Kern, Nano Lett., 2007, 7, 3499–3503.
7 4 J. Peng, W. Gao, B. K. Gupta, Z. Liu, R. Romero-Aburto, L. H. Ge, L. Song, L. B.
8 Alemany, X. B. Zhan, G. H. Gao, S. A. Vithayathil, B. A. Kaipparettu, A. A. Marti,
9 T. Hayashi, J. J. Zhu, P. M. Ajayan, S. A. Vithayathil, B. A. Kaipparettu, A. A.
10 Marti, T. Hayashi, J. J. Zhu and P. M. Ajayan, Nano Lett., 2012, 12, 844−849.
11 5 K. J. Wei Y., Wang, W. Q. Han, J. S. Li, X. Y. Sun, J. Y. Shen and L. J. Wang, J.
12 Power Sources, 2016, 318, 57−65.
13 6 P. Han, T. Yuan, L. Yao, Z. Han, J. H. Yang and S. Y. Zheng, Nanoscale Res. Lett.,
14 2016, 11, 1–8.
15 7 W. Xie, H. F. Cheng, Z. Y. Chu, Z. H. Chen and C. G. Long, Ceram. Int., 2011, 37,
16 1947–1951.
17 8 Q. Liu, K. Wang, J. Huan, G. B. Zhu, J. Qian, H. P. Mao and J. R. Cai, Analyst,
18 2014, 139, 2912–2918.
19 9 W. Q. Wu, X. Hua, S. L. Luo, C. B. Liu, Y. H. Tang and L. M. Yang, Sens.
20 Actuators B, 2016, 222, 747–754.
21 10 Q. Liu, J. Huan, A. R. Fei, H. P. Mao and K. Wang, Talanta, 2015, 134, 448–452.
22