Supporting Information Chemically Modulated Carbon Nitride Nanosheets for Highly Selective Electrochemiluminescent Detection of Multiple Metal-ions Zhixin Zhou, Qiuwei Shang, Yanfei Shen, Linqun Zhang, Yuye Zhang, Yanqin Lv, Ying Li, Songqin Liu, and Yuanjian Zhang* Jiangsu Province Hi-Tech Key Laboratory for Bio-Medical Research, Jiangsu Optoelectronic Functional Materials and Engineering Laboratory, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China Medical School, Southeast University, Nanjing 219, China Email address: Yuanjian.Zhang@seu.edu.cn S1
2 CN-4 CN-45 CN-5 CN-55 CN-6 CN-65 2 4 6 2θ (degree) -NH 2 CN-4 CN-45 CN-5 CN-55 CN-6 CN-65 4 3 2 1 Wavenumber (cm -1 ) Figure S1. XRD (a) and FT-IR of CN-T (T=4, 45, 5, 55, 6 and 65). All patterns of as-obtained CN prepared at different temperatures exhibited a (2) peak at ca. 27 o (2θ), corresponding to the interlayer distance. 1 Interestingly, this peak gradually shifted to a larger diffraction angle and became narrower with the increase of the synthesis temperature, indicating that the CN synthesized at a higher temperature had a denser stacking which may lead to a stronger interlayer electron coupling. 2-4 Meanwhile, the peak at 13. o (2θ), corresponding to approximate dimension of the tri-s-triazine unit, gradually became weaker and broader due to the increase of distortion of planar structure. 3 The chemical structure of various CN was studied by Fourier transform infrared spectra (FT-IR, Figure S1b) spectroscopy and elemental analysis (EA, Table S1). Although all sample showed that the peaks around 8 cm -1 originated from the triazine ring breathing mode, the peaks at 12-17 and 3-35 cm -1 were distinctive, indicating that the chemical structure of CN polymerized at different temperature was different. The chemical structure of the as-prepared CN was further confirmed by elemental analysis shown in Table S1. The C/N molar ratio increased with the increase of temperature. Therefore, by modulating the synthesis temperature from 4 to 65 o C, the chemical structure and condensation degree of CN can be facilely manipulated, which would greatly favor the further liquid-exfoliation of carbon nitride nanosheets with tunable chemcial structures. S2
2 4 o C 2 5 o C 3 65 o C 2 % 1 % 1 % 1 Size (nm) Size (nm) Size (nm) Figure S2. Size distribution of CNNS-4 (a), CNNS-5 and CNNS-65 evaluated by DLS, except for CNNS-4 which was evaluated from TEM measuring by more than 2 individual sheets due to the inapplicability of DLS. The average equivalent size of CNNS-4, CNNS-5 and CNNS-65 was ca. 4 nm, 6 nm and 3 nm, respectively. Figure S3. Tyndall effect of the aqueous dispersion of carbon nitride nanosheets CNNS-T (from left to right, T = 4, 45, 5, 55, 6 and 65). S3
Nomarlized PL 1..8.6.4.2. 18 36 54 72 Time (s) CNNS-4 CNNS-45 CNNS-5 CNNS-55 CNNS-55 CNNS-6 PL Intensity (a.u.) M.5 M.1 M.3 M.5 M.8 M 1 M 4 5 6 7 PL Intensity (a.u.) ph=1 ph=3 ph=5 ph=7 ph=9 ph=11 ph=13 (d) PL Intensity (a.u.) 4 5 6 7 2 4 6 8 1 12 14 ph Figure S4. (a) Photobleaching properties of the CNNS-T (T = 4, 45, 5, 55, 6 and 65) exfoliated from CN-T under continuous excitation at 3 nm. Effects of ion concentration on fluorescent intensity of CNNS-55. (c-d) Effects of ph on photoluminescent intensity of the CNNS-55. Normarlized PL (a.u.) CNNS-4 CNNS-65 CNNS-5 S-CNNS-55 4 5 6 Figure S5. PL spectra of CN-4, CN-5, CN-65 and S-CN-55. S4
-1.5-1. -.5. ECL Intensity (a.u.) Cathode ECL ECL Intensity (a.u.) Time (s) ECL Intensity (a.u.) CNNS-4+Cu 2+..4.8 1.2 1.6 Potential (V) Time (s) CNNS-65+Cd 2+ ECL Intensity (a.u.) Anodic ECL Time (s) Time (s) Figure S6. Cathode (up) and anodic (bottom) ECL-potential curves of CNNS-5 (a). Inset: the stability of cathode (up) and anodic (bottom) ECL curves of CNNS-5 under ten continuous cycles of cyclic voltammetry scan. The ECL intensity change of CNNS-4 and CNNS-65 after adding the Cu 2+ and Cd 2+, respectively, with time. S5
.15.1.5 Cu 2+ 1.6 1.2.8.4 Ni 2+.. 2 4 6 8.1 2 4 6 8 Cd 2+.5. 2 4 6 8 Figure S7. UV-vis absorption spectra of Cu 2+ (a), Ni 2+ and Cd 2+ (d) in aqueous solution. S6
2 1 CNNS-65-ECL CNNS-65 CNNS-65+Ni 2+ ECL intensity (a.u.) 3 2 1 CNNS-ECL CNNS-4 CNNS-4-Ni 2+ ECL intensity (a.u.) 4 6 8 2 4 6 8 2 1 CNNS-65-ECL CNNS-65 CNNS-65+Cd 2+ ECL intensity (a.u.) (d) Intensity (a.u.) CNNS-65 CNNS-65+Cd 2+ 4 6 8 2 4 6 Time (ns) Figure S8. UV-vis absorption spectra in the absence and presence of Ni 2+ and ECL emission spectra of CNNS-65 (a) and CNNS-4. UV-vis absorption spectra in the absence and presence of Cd 2+ and ECL emission spectra of CNNS-65. Time-resolved PL spectra of CNNS-65 in the absence and presence of Cd 2+ (d). S7
N Si CNNS-4+Cu 2+ Intensity (a.u.) C O Cu Cl 1 2 3 4 KeV CNNS-5+Ni 2+ N Si Intensity (a.u.) C O Ni 1 2 3 4 KeV CNNS-65+Cd 2+ Intensity (a.u.) C N Si O Cl Cd 1 2 3 4 KeV Figure S9. EDX spectra of CNNS-4+Cu 2+, CNNS-5+Ni 2+ and CNNS-65+Cd 2+. The atomic ratios of Cu 2+, Ni 2+, and Cd 2+ in them were 2.7 %,.6% and.6%, respectively. S8
.8.4 (αhν) 2 12 9 6 3 CNNS-4 CNNS-5 CNNS-65 2.5 3. 3.5 4. Energy (ev) Intensity (a.u.) CNNS-4 CNNS-5 CNNS-65 2.59 ev 2.85 ev. 36 42 48 54 1.69 ev 2 4 6 8 1 Binding Energy (ev) Figure S1. (a) UV-Vis absorption spectra of the CNNS-4, CNNS-5, and CNNS-65. Inset: (αhν) 2 versus hυ curve of CNNS-4, CNNS-5, and CNNS-65. The horizontal black line marks the baseline; the other lines are the tangents of the curves. The intersection value is the band gap. XPS VB spectra of the CNNS-4, CNNS-5, and CNNS-65; Scheme of relative CB and VB positions for the CNNS-4, CNNS-5, and CNNS-65. CB: conduction band; VB: valence band. S9
Scheme S1. The proposed copolymerization process of urea with ATCN at 55 o C for S-CN-55. Table S1. Elemental analysis of as-prepared bulk CN-T (T= 4, 5 and 65) Sample C a N a H a C/N b CN-4 31.59 61.21 3.26.6 CN-5 33.7 6.85 2.33.65 CN-65 35.4 61.47 1.9.67 a wt.%; b molar ratio S1
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