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Supplementary Material
Ratiometric fluorescent sensing of Pb2+ and Hg2+ with two types of
carbon dot nanohybrids synthesized from the same biomass
Zhaoying Liua, Wenying Jina,*, Fangxiao Wanga, Tuanchuan Lia, Jinfang Niea,*,
Wencheng Xiaoa, Qing Zhangb, Yun Zhanga,*
a College of Chemistry and Bioengineering, Guilin University of Technology, Guilin
541004, P.R. China.
b College of Environmental Science and Engineering, Guilin University of
Technology, Guilin 541004, P.R. China.
*Corresponding author.
E-mail addresses: [email protected]; [email protected]; [email protected].
Tel: +86 773 5896453; Fax: +86 773 5896839.
S1
Fig. S1. Fluorescence emission spectra of a dilute aqueous solution of dual-emission
CD nanohybrids at various excitation wavelengths.
S2
Fig. S2. Fluorescence emission spectra of a dilute aqueous solution of three-emission
CD nanohybrids at various excitation wavelengths.
S3
Fig. S3. Fluorescence lifetime of two-emission CD nanohybrids (A) before and (B)
after the addition of Pb2+.
S4
Fig. S4. Fluorescence lifetime of three-emission CD nanohybrids (A) before and (B)
after the addition of Hg2+.
S5
Fig. S5. Infrared spectra of the two-emission CD nanohybrids before and after the
addition of (A) Pb2+ and (B) other metal ions.
S6
Fig. S6. Infrared spectra of the three-emission CD nanohybrids before and after the
addition of (A) Hg2+ and (B) other metal ions.
S7
Fig. S7. (A) Full XPS spectrum, (B) C 1s XPS spectrum, (C) N 1s CPS spectrum and
(D) O 1s XPS spectrum of the dual-emission CD nanohybrid.
S8
Fig. S8. (A) Full XPS spectrum, (B) C 1s XPS spectrum, (C) N 1s CPS spectrum and
(D) O 1s XPS spectrum of the three-emission CD nanohybrid.
S9
Fig. S9. UV/Vis spectra of the sixteen types of metal ions, i.e., Al3+, Fe3+, Cr3+, Cu2+,
Mg2+, Hg2+, Pb2+, Zn2+, Ca2+, Cd2+, Mn2+, Co2+, Ag+, Na+ and K+.
S10
Fig. S10. Optimization of the concentration of the dual-emission CD nanohybrids,
i.e., the volume ratio of original CD nanohybrid to buffer applied for Pb2+ detection.
The results suggested that the volume ratio of 10/490 should be chosen as the optimal
level of the dual-emission CD nanohybrids because it gave the highest I653/I493 value.
S11
Fig. S11. Optimization of reaction pH applied for Pb2+ detection. The results
suggested that pH 7 should be chosen as the optimal pH because it gave the highest
I653/I493 value.
S12
Fig. S12. Optimization of the reaction temperature applied for Pb2+ detection. The
results suggested that the tested reaction temperatures ranging from 4 to 60 oC did not
show significant effects on the I653/I493 values. Thus, all the following experiments
were carried out at room temperature.
S13
Fig. S13. Optimization of the reaction time applied for Pb2+ detection. The results
suggested that 120 min should be chosen as the optimal reaction time because no
significant increase was observed in the I653/I493 value when the longer reaction time
was applied.
S14
Fig. S14. Optimization of the concentration of the three-emission CD nanohybrids,
i.e., the volume ratio of original CD nanohybrid to buffer applied for Hg2+ detection.
The results suggested that the volume ratio of 12.5/487.5 should be chosen as the
optimal level of the three-emission CD nanohybrids because it gave the highest
I611/I491 value.
S15
Fig. S15. Optimization of reaction pH applied for Hg2+ detection. The results
suggested that pH 7 should be chosen as the optimal pH because it gave the highest
I611/I491 value.
S16
Fig. S16. Optimization of the reaction temperature applied for Hg2+ detection. The
results suggested that the tested reaction temperatures ranging from 25 to 60 oC did
not show significant effects on the I611/I491 values. Thus, all the following experiments
were carried out at room temperature.
S17
Fig. S17. Optimization of the reaction time applied for Hg2+ detection. The results
suggested that 120 min should be chosen as the optimal reaction time because no
significant increase was observed in the I611/I491 value when the longer reaction time
was applied.
S18
Table S1 Recovery of Pb2+ in Lijiang river water samples
Sample No. Founda
(nM)Added(nM)
Calculatedb
(nM)Recovery
(%)RSDc
(%, n = 6)
1 0.00 5.00 5.28 105.6 5.70
2 0.00 10.00 9.97 99.7 1.99
3 0.00 20.00 18.28 91.4 1.40
a Original Pb2+ concentrations in the samples detected using atomic absorption spectroscopy;
b The total Pb2+ concentrations in the samples determined using the proposed method;
c RSD, relative standard deviations.
S19
Table S2 Recovery of Hg2+ in Lijiang river water samples
Sample No. Founda
(nM)Added(nM)
Calculatedb
(nM)Recovery
(%)RSDc
(%, n = 6)
1 0.00 2.00 1.96 98.0 4.10
2 0.00 3.00 3.15 105.0 5.98
3 0.00 4.00 3.81 95.3 6.90
a Original Hg2+ concentrations in the samples detected using atomic absorption spectroscopy;
b The total Hg 2+ concentrations in the samples determined using the proposed method;
c RSD, relative standard deviations.
S20