Electronic Supplementary Material for
A glassy carbon electrode modified with gold nanoparticle-encapsulated graphene oxide hollow microspheres for voltammetric sensing of nitrite
Fuhua Zhang,a,b Yawen Yuan,a,b Yiqun Zheng,b Hua Wang,b Tonghao Liu,c Shifeng Houb, c *
aSchool of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, P. R. China
bNational Engineering Research Center for Colloidal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
cJining Research Center for Carbon Nanomaterials, Jining, Shandong Province, 272100, P. R. China
*Corresponding author: Prof. Shifeng Hou. E-mail:
Fig. S1. The thermos gravimetric analysis (TGA) data of AuNP/rGO HMS.
Fig. S2. SEM images of AuNP/rGO HMS/GCE with different magnifications.
Fig. S3. Cyclic voltammograms of AuNP/rGO HMS/GCE in 0.10 M PB (pH 4.7) with 0.4 mM nitrite. Scan rate: 50 mV•s−1.50 times of (A) Cl-, CO32-, SO42-, (B) uric acid, (C)vitamin C and 100 times of (D) Mn2+, I-, (E) Br-, Fe3+.
Fig. S4. Typical SEM images of AuNP/rGO HMS captured from another area of the same sample as shown in Figure 1.
pH effect on the measured nitrite
To further investigate the electrocatalytic process of nitrite at AuNP/rGO HMS/GCE, the effect of pH value of the solution on the electrochemical oxidation of nitrite was studied at the AuNP/rGO HMS/GCE. Table S2 shows the Ep and Ip which were obtained in a solution with the pH value ranging from 3.0 to 7.0. The peak current increases as the pH increases in the range of pH value 3.0 to 4.7, while in the range of 4.7 to 7.0, the peak current decreases. The possible reason is that the nitrite anion is not stable in strong acid medium [34] and can undergo the following reaction equation:
2H+ + 3NO2- → 2NO + NO3-+ H2O
So the peak current increases as the pH value increases in ranging from 3.0 to 4.7. When the pH value in the range of 4.7 to 7.0, it leads to a shortage proton of solution, and thus deactivate the electrocatalytic oxidation of nitrite [35], so that the peak current would naturally decrease. Therefore, pH 4.7 was chosen for further studies.
Table S1. Comparison of different nitrite sensors documented in literature.
Modified material / Detection limit / Linear range / Ref.Nafion/SLGnP–TPA–Mb/GC / 10 / 50-2500µM / [3]
AuNP/Ch/GCE / 0.1 / 0.4-750µM / [4]
AuNP/P3MT/GCE / 2.3 / 10-1000µM / [5]
AuNP/GCE / 2.4 / 10-1000µM / [6]
CR-GO/GCE / 1.0 / 8.9-167µM / [7]
Poly(toluidine blue)-MWCNTs / 19 nM / 39 nM–1.1 mM / [8]
AuCu NCN / 0.20 µM / 10–4000 µM / [9]
CDs-Au-N / 0.060 µM / 0.1–2000 µM / [10]
np-PdFe / 0.8 µM / 0.5–25.5 mM / [11]
Co NP-PEDOT-GE/GCE / 0.15µM / 0.5–240 µM / [12]
AuNP/SG/GCE / 0.20 µM / 10–3960 µM / [13]
amFc–rGO / 0.35 μM / 2.5- 50 μM / [14]
Cyt c/Nafion/Cu-LDH/Au / 0.2 µM / 0.75–123.25 µM / [15]
PEDOT/(CNCC/PDDA)4 / 0.057 µM / 0.2–1730 µM / [16]
f-ZnO@rFGO / 33 μM / 10 μM–
8 mM / [17]
PEDOT/AuNP / 0.060 µM / 0.2–1400 µM / [18]
CoOx/CNT/GCE / 0.30 µM / 0.5–249 µM / [19]
Ni7S6 / 0.30 µM / 0.001–1.4 mM / [20]
Ni7S6/MWCNTs / 0.30 µM / 0.001–4.2 mM / [20]
AuNP/rGO HMS/GCE / 0.50 µM / 5-2600 µM / This work
Table S2. Ep and Ip of AuNP/rGO HMS/GCE in 0.10 M PB with 0.60 mM nitrite at different pHs. Scan rate: 50 mV•s−1.
Ep (V) / 0.824 / 0.825 / 0.831 / 0.855 / 0.835 / 0.834
Ip(μA) / 71.292 / 73.098 / 92.930 / 74.272 / 69.550 / 67.100
Table S3. The tested data of nitrite using AuNP/rGO HMS/GCE at various concentrations in tap water and USE .
This techniqueSample No. / Added (μM) / Found (μM) / Recovery (%) / RSD (n=5, %)
1 / 20 / 20.31 / 101.55 / 1.92
2 / 100.00 / 100.18 / 100.18 / 1.45
The Nitrite Ion-Selective Electrode result
1 / 20 / 20.8 / 104
2 / 100.00 / 98.2 / 98.2
3 / 200.00 / 192.0 / 96.0
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