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Supplementary Materials
Selective capture of Pb2+ in rice phloem sap using glutathione-functionalized gold
nanoparticles/multi-walled carbon nanotubes: enhancing anti-interference
electrochemical detection
Min Jiang†ab, Hui-Ru Chen†bc, Shan-Shan Li†ab, Rui Liangbc , Jin-Huai Liuab, Yang
Yang*bc, Yue-Jin Wubc, Meng Yang*ab and Xing-Jiu Huang*ab
a Key Laboratory of Environmental Optics and Technology, And Institute of
Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, People’s
Republic of China
b University of Science and Technology of China, Hefei 230026, People’s Republic of
China
c Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, People’s
Republic of China
† M.J., H.R.C. and S.S.L. contributed equally to this work.
* Correspondence should be addressed to X.J.Huang, M. Yang and Y.Yang.
E-mail: [email protected] (X.J.H); [email protected] (M.Y);
[email protected] (Y.Y).
Tel.: +86-551-65591167; fax: +86-551-65592420.
Electronic Supplementary Material (ESI) for Environmental Science: Nano.This journal is © The Royal Society of Chemistry 2018
Contents
1. Experimental section and discussion
1.1. Apparatus
1.2. Electrochemical detection of Pb2+
1.3. The discussion of cyclic voltammetry and electrochemical impedance
spectroscopy
2. Figure
Fig. S1. The real picture of collection of phloem sap and corresponding collection
device
Fig. S2. Pathway of electron transfer through the MWCNTs-GSH-Au-GSH
Fig. S3. TEM image of (a) MWCNTs-Au-GSH and (b) MWCNTs-GSH-Au-GSH
Fig. S4. Typical SWASV response of MWCNTs-GSH-Au-GSH modified GCE for
analysis of Pb2+ mixed with rice phloem sap for 1 minute and 24 hours
Fig. S5. Optimal experimental conditions at MWCNTs-GSH-Au-GSH electrode
Fig. S6. SWASV response of bare, MWCNTs, MWCNTs-GSH, MWCNTs-GSH-Au,
and MWCNTs-Au-GSH GCE for analysis of Pb2+
Fig. S7. SWASV response of 0.1 M Pb2+ at MWCNTs-GSH-Au-GSH GCE in the
presence of 100 M Cl-, 100 M K+, 0-22 M Fe3+, 100 M Ca2+, 100 M Mg2+, 100
M Mn2+, 0-1 M Zn2+, and 0-0.5 M Cu2+ in 0.1 M HAc-NaAc solution
Fig. S8 SWASV detection of 1 M Pb2+ in the absence and presence of main
coexisting inorganic ions on glassy-carbon electrode
Fig. S9. Fourier transforms (FTs) of EXAFS data with fits to spectra
Fig. S10. Cyclic voltammograms and electrochemical impedance spectra at
MWCNTs-GSH-Au-GSH electrode
Fig. S11. Scan rate study at MWCNTs-GSH-Au-GSH electrode
3. Table
Table S1. Soil physical and chemical properties
Table S2. Comparison of electrochemical performance for voltammetric detection of
Pb2+
Table S3. Results of EXAFS analysis
Table S4. Results of XPS analysis
4. Reference
1. Experimental section and discussion
1.1. Apparatus and instruments
Electrochemical measurements were performed with CHI 660D computer-controlled
potentiostat (Chenhua Instruments Co., Shanghai) with the MWCNTs-GSH-Au-GSH
modified glassy-carbon electrode (GCE) as working electrode, Ag/AgCl electrode as
reference electrode, and Pt wire as counter electrode. Nanomaterials were conducted
by SEM images (FESEM, Quanta 200 FEG, FEI Company). TEM and HRTEM as
well as EDS (JEM-2010), XRD (Philips X’Pert Pro X-ray diffractometer), FT-IR
spectrometer (Nicolet Nexus-670), XPS (VG ESCALAB MKII spectrometer), XAFS
(BL14W1 beamline of the Shanghai Synchrotron Radiation Facility). The main
coexisting inorganic ions in the phloem sap were determined by ICPMS (Plasma
Quad 3, Thermo Electron Co., United States).
1.2. Electrochemical detection of Pb2+
Pb2+ was gradually added to NaAc-HAc solution, performing a deposition voltage (-1
V) for 210 s, then stripping and finally applying a deposition voltage (0.8 V) for
desorption. SWASV responses was performed with frequency of 15 Hz, amplitude of
25 mV and a step potential of 4 mV.
1.3. The discussion of cyclic voltammetry and electrochemical impedance
spectroscopy
Cyclic voltammetry (CV, Figure S8a) and electrochemical impedance spectroscopy
(EIS, Figure S8b) of bare, MWCNTs, MWCNTs-GSH, MWCNTs-GSH-Au,
MWCNTs-Au-GSH and MWCNTs-GSH-Au-GSH electrodes were tested in
potassium ferricyanide (K3Fe(CN)6) solution. Peak current of these six kinds of
electrodes reveal similar and great electron-transfer kinetics for K3Fe(CN)6 redox
probe. Electron transfer impedance values are all small, indicating the good
conductivity of these nanomaterials and the good capability for electrons transfer.
Real electrochemical surface areas (RESA, Figure S9) of the bare, MWCNTs,
MWCNTs-GSH, MWCNTs-GSH-Au, MWCNTs-Au-GSH and MWCNTs-GSH-Au-
GSH modified electrodes are 0.068, 0.056, 0.052, 0.059, 0.063 and 0.052 cm2,
respectively.
2. Figure
Fig. S1 The real picture of (a) collection of phloem sap, (b) corresponding collection device, (c) centrifuge tube, and (d) absorbent cotton wool.
Fig. S2 Pathway of electron transfer through the MWCNTs-GSH-Au-GSH.
Fig. S3 TEM image of (a) MWCNTs-Au-GSH and (b) MWCNTs-GSH-Au-GSH.
Fig. S4 Typical SWASV response of MWCNTs-GSH-Au-GSH modified GCE for analysis of Pb2+ mixed with rice phloem sap for (a) 1 minute, (b) 24 hours.
Fig. S5 Optimum experimental conditions. Influence of (a) supporting electrolytes;(b) pH value; (c) deposition potential; and (d) deposition time on SWASV response of MWCNTs-GSH-Au-GSH electrode. Data were evaluated of 0.3 M Pb2+.
Fig. S6 SWASV response of (a) bare, (b) MWCNTs, (c) MWCNTs-GSH, (d) MWCNTs-GSH-Au, and (e) MWCNTs-Au-GSH electrode for analysis of Pb2+ in different concentration ranges. Inset in panel a, b, c, d and e are the corresponding linear calibration plot of peak current against Pb2+ concentrations, respectively.
Fig. S7 SWASV response of 0.1 M Pb2+ at MWCNTs-GSH-Au-GSH modified GCE in the presence of (a) 100 M Cl-, (b) 100 M K+, (c) 0-22 M Fe3+, (d) 100 M Ca2+, (e) 100 M Mg2+, (f) 100 M Mn2+, (g) 0-1 M Zn2+, and (h) 0-0.5 M Cu2+ in HAc-NaAc solution.
Fig. S8 SWASV detection of 1 M Pb2+ in the absence and presence of main coexisting inorganic ions on glassy-carbon electrode.
Fig. S9 (a) The k3-weighted Cu K-edge XAFS spectra of MWCNTs-GSH-Au-GSH-Cu2+, k3-weighted Fe K-edge XAFS spectra of MWCNTs-GSH-Au-GSH-Fe3+ and k3-weighted Zn K-edge XAFS spectra of MWCNTs-GSH-Au-GSH-Zn2+. (b) Fourier transforms of EXAFS data with fits to spectra.
Fig. S10 CV (a) and EIS (b) for bare, MWCNTs, MWCNTs-GSH, MWCNTs-GSH-Au, MWCNTs-Au-GSH, and MWCNTs-GSH-Au-GSH modified GCE in K3Fe(CN)6 solution. Scan rate: 100 mV s-1.
Fig. S11 Scan rate test in K3Fe(CN)6 solution on bare, MWCNTs, MWCNTs-GSH, MWCNTs-GSH, MWCNTs-GSH-Au, MWCNTs-GSH-Au-GSH, and MWCNTs-Au-GSH modified electrode, respectively. Inset is the corresponding plots of current versus the square root of the scan rate with a linear trend line.
3. Table
Table S1 Soil physical and chemical properties.Organic matter
(g / kg) pH Pb (mg/kg)
Total nitrogen (g/kg)
Total phosphorus (g/kg)
Available potassium (mg/kg)
20.3 6.8 30 0.95 1.32 101.46
Table S2 Comparison of electrochemical performance for voltammetric detection of Pb2+.
Electrode material Linear range (μM) SensitivityμA μM−1
LOD (μM) Sample Ref.
nanoplate-stacked Fe3O4 0.04-0.2 24.6 0.0152 water 1
Terephthalic acid - iron oxide 0.06-1.1 12.149 0.04 water 2
O2-plasma oxidized MWCNTs 0.5–4.5 3.55 5.7×10-5 water 3
amino-carbon microspheres 0.6-1.8 16.13 0.38 water 4
TCA-MWCNTs. 0.0002 -0.01 7548 4 × 10−5 water 5
fluorinated graphene oxide 0.3-5.0 10.32 0.01 water 6
Au NPs 0.2-1.4 17.63 ------ water 7
AlOOH-RGO 0.3-1.1 2.97 7.6×10-5 water 8
N-doped graphene 0.01-9 4.946 0.005 water 9
G/MWCNTs/Bi 0.0024 -0.14 29.4 0.001 water 10
MWCNT-GSH-Au-GSH 0.02-0.35 58.4 0.01rice phloem
sapthis
work
Table S3 Results of EXAFS analyses. CN = coordination number, R = interatomic distance, σ2 = Debye-Wailer factor and ΔE0 = phase shift.
Sample first shell CN R(Å) s2(Å2) E0 (eV) ΔE0 (eV)
MWCNTs-GSH-Au-GSH-Cu2+ Cu--O/N 3.46 1.95 0.07 -2.23 1.37
MWCNTs-GSH-Au-GSH-Fe3+ Fe--O/N 4.71 1.99 0.06 -2.24 1.26
MWCNTs-GSH-Au-GSH-Zn2+ Zn--S 4.58 2.21 0.03 -4.37 1.81
MWCNTs-GSH-Au-GSH-Pb2+ Pb--O/N 3.51 2.43 0.15 -3.92 2.61
Table S4 Results of XPS analysis. MWCNTs-GSH-Au-GSH adsorbed coexisting ions of Pb2+, Cu2+, Fe3+ and Zn2+ for different times.
210 s 2 hours 4 hoursPb/C (%) 0.43 0.49 0.5Cu/C (%) 0.14 0.19 0.26Fe/C (%) 0.18 0.19 0.27
Zn/C (%) 0 0 0.04
Atom RatioAdsorption Time
4. References
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