Supporting Information

Bi-functional Au/FeS (Au/Co3O4) Composite for In-situ SERS Monitoring and Degradation of Organic Pollutants

Shuzhen Ma, Qian Cai, Kailing Lu, Fan Liao*, Mingwang Shao*

Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, P. R.E-mail: (F Liao); (MW Shao)

  1. The size distribution histogram of the Au nanoparticles decorated on the surface of FeS andCo3O4.

Fig. S1 The size distribution histogram of Au nanoparticles based on 100 particles from theFeS multistructure at high-magnification image of SEM.

Fig. S2 The size distribution histogram of Au nanoparticles based on 100 particles from the Co3O4 nanoplateat high-magnification image of SEM.

2. The normal Raman spectrum of 0.2 M R6G aqueous solution.

Fig. S3 The normal Raman spectrum of 0.2 M R6G aqueous solution.

3. The background Raman spectra of the SERS active substrates

Fig. S4 The background Raman spectra of the SERS active substrates without further pulling baseline. (a)the Raman spectrum of Au/FeS substrate, and (b)the Raman spectrum of Au/Co3O4 substrate.

4. The relative standard deviation (RSD) of carbon skeleton stretching modes

Fig. S5 The intensities of four main Raman vibrations of R6G aqueous solution (5×10-7 M) for 100 spots

  1. Investigation of the catalytic oxidation process in the absence of Au/FeS (Au/Co3O4) catalyst or H2O2.

Fig. S6 The UV-vis spectra of the catalytic oxidation process of OPD molecules: (a) only the Au/FeS catalyst was added without H2O2, (b) only the Au/Co3O4 catalyst was added without H2O2, (c) only the H2O2 was added without catalysts,and (d) the absorption-time course curves of OPD molecules at 446 nm.

6. Investigation of the degradation process in the absence of Au/FeS (Au/Co3O4) catalyst or H2O2.

Fig. S7The UV-vis spectra of thedegradation process of R6G molecules: (a) only the Au/FeS catalyst was added without H2O2, (b) only the Au/Co3O4 catalyst was added without H2O2, (c) only the H2O2 was added without catalystsand (d) the absorption-time course curves of R6G molecules at 526 nm.

7. The relationship between the peak intensity and concentration of R6G molecules.

Before the SERS monitoring detection, the work curves of peak intensity and concentration of R6G were obtained. The relationship between the SERS intensity and the concentration of R6G molecules (1×10-7 - 1×10-4 M) by employing Au/FeS and Au/Co3O4as substrates are displayed in Figs. S5 and S6, respectively. The vibration bands of R6G molecules at 1306, 1360, 1503 and 1646 cm-1 were chosen as marker peaks for analysis when using Au/FeS as the substrate. And the linear relationships are expressed as: I = 1.66 × 108 CR6G + 790.4, I = 2.69 × 108 CR6G + 1141.4, I = 2.07 × 108 CR6G + 812.4, I = 1.11 × 108 CR6G + 414.1, respectively. The vibration bands of R6G molecules at 1312, 1359, 1511 and 1649 cm-1 were chosen as marker peaks for analysis when using Au/Co3O4 as the substrate, and the linear relationships are expressed as: I = 1.03 × 108 CR6G + 392.9, I = 1.78 × 108 CR6G + 431.7, I = 1.52 × 108 CR6G + 416.7, I = 7.58 × 107 CR6G + 197.0, respectively. It is clearly presented that the relationship between the peak intensity and the concentration of R6G molecules is linear in the range of 1×10-7 - 1×10-5 M.Based on these equations, the peak intensity may be transformed into the corresponding concentration. Each inset is the amplification of the linear part from the corresponding image. The goodness of fit and standard deviation from each curve are listed in Table S1 and Table S2.

Fig. S8 The work curves of Raman peak intensity and concentration of R6G at (a) 1306 cm-1, (b) 1360 cm-1, (c) 1503 cm-1, and (d) 1646 cm-1 by employing Au/FeS as the substrate

Fig. S9 The work curves of Raman peak intensity and concentration of R6G at (a) 1312 cm-1, (b) 1359 cm-1, (c) 1511 cm-1, and (d) 1649 cm-1 employing Au/Co3O4 as the substrate.

Table S1. The goodness of fit and standard deviation of SERS signals with the R6G concentration of 10-7-10-5 M based on Au/FeS substrate.

Raman shift / cm-1 / 1306 / 1360 / 1503 / 1646
R / 0.97635 / 0.97602 / 0.97827 / 0.97454
SD / 184.46141 / 300.76645 / 220.31079 / 127.89391

Table S2. The goodness of fit and standard deviation of SERS signals with the R6G concentration of 10-7-10-5 M based on Au/Co3O4 substrate.

Raman shift / cm-1 / 1312 / 1359 / 1511 / 1651
R / 0.98441 / 0.99145 / 0.99680 / 0.97927
SD / 92.52202 / 117.15978 / 61.12261 / 78.56412

8. The influence of laser during the SERS detection in the process of R6G degradation.

Fig. S10 (a)The SERS signals of R6G molecules by employing Au/FeS as substrates without adding of H2O2; and (b) The fluctuation of SERS intensity of the typicalbands of R6G with the laser irradiation.

Fig. S11 (a)The SERS signals of R6G molecules by employing Au/Co3O4 as substrates without adding of H2O2; and (b) The fluctuation of SERS intensity of the typicalbands of R6G with the laser irradiation.

S1