Photo-reduction and Stabilization Capability of Molecular Weight. Fractionated Natural Organic Matter in Transformation of Silver Ion to

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1 Supporting information Photo-reduction and Stabilization Capability of Molecular Weight Fractionated Natural Organic Matter in Transformation of Silver Ion to Metallic Nanoparticle Yongguang Yin 1, Mohai Shen 1, Xiaoxia Zhou 1, Sujuan Yu 1, Jingbo Chao, Jingfu Liu 1*, and Guibin Jiang State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 10008, China Chemical Metrology and Analytical Science Division, National Institute of Metrology, Beijing 10001, China 1 * Corresponding author: Tel. +8(10)-8919; jfliu@rcees.ac.cn 17 Number of pages: 18 Number of figures: Number of tables: S1

2 Table S1 Molar absorptivity at 80 nm and Ex/Em wavelength and intensity of florescence peak of pristine and M f -NOM. molar absorptivity at 80 nm (1 mol -1 cm -1 OC) pristine >100 kda kda 10-0 kda -10 kda < kda Ex/Em (nm) / 0/8 70/8 0/0 /0 0/ peak intensity of florescence S

3 Table S Dual-mode distribution of AgNPs size in pristine and M f -NOM determined by DLS. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer (ph 8.0) under simulated sunlight irradiation for 9 h. Size of Peak 1±SD (d. nm) Size of Peak ±SD (d. nm) Pristine NOM 1.9±0.87.7±0. >100 kda M f -NOM.8± ± kda M f -NOM.±1.8.1± kda M f -NOM 7.1±.0.± kda M f -NOM.7± ±0.8 < kda M f -NOM 7.8±0..0±0.78 S

4 Figure S1. Transmittance of UV-B block film (cut-off wavelength 1 nm), UV Block film (cut- off wavelength 81 nm) and aluminum foil. S

5 Figure S. The molecular weight distribution of M f -NOM fraction in SRNOM. S

6 Figure S. Light spectrum from (a) solar simulator (Xe lamp), (b) Hg lamp, and (c) Hg lamp with glass filter. S

7 Figure S. Transmittance of glass filters to separate nm light from Hg lamp. S7

8 Figure S. UV-vis spectra of pristine and M f -NOM. Solution conditions: mg L -1 DOC pristine or M f -NOM in mmol L -1 borate buffer (ph 8.0). S8

9 Figure S. Fluorescence excitation-emission spectra of pristine and M f -NOM. (a) pristine NOM, (b) >100 kda M f -NOM, (c) kda M f -NOM, (d) 10-0 kda M f -NOM, (e) -10 kda M f - NOM, and (f) < kda M f -NOM. Solution conditions: mg L -1 DOC pristine or M f -NOM in mmol L -1 borate buffer (ph 8.0). S9

10 Figure S7. UV-vis spectra of the solution after different irradiation time. (a) pristine NOM, (b) >100 kda M f -NOM, (c) kda M f -NOM, (d) 10-0 kda M f -NOM, (e) -10 kda M f - NOM, and (f) < kda M f -NOM. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer (ph 8.0) S10

11 Figure S8. TEM images (a and b), SAED (c) and EDS (d) of the photo-induced AgNPs in SRNOM solution. The scale bars are 0 nm ad nm in (a) and (b), respectively. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine SRNOM, mmol L -1 borate buffer (ph 8.0). S11

12 1 Figure S9. TEM images of the photo-induced AgNPs in Mf-NOM solution after 9 h simulated sunlight irradiation. (a) >100 kda Mf-NOM, (b) < kda Mf-NOM. The scale bars are 0 nm in (a) and (b). Solution conditions: 0. mmol L-1 AgClO, mg L-1 DOC Mf-NOM, mmol L-1 borate buffer (ph 8.0) S1

13 Figure S10. UV-vis spectra of the solution after 9 h simulated sunlight irradiation at different ph. (a) pristine NOM, (b) >100 kda M f -NOM, (c) kda M f -NOM, (d) 10-0 kda M f - NOM, (e) -10 kda M f -NOM, and (f) < kda M f -NOM. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer S1

14 Figure S11. TEM images of the photo-induced AgNPs in < kda M f -NOM solution at different ph after 9 h simulated sunlight irradiation. (a) ph 7., (b) ph 8.0. The scale bars are 100 nm. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC < kda M f -NOM, mmol L -1 borate buffer. S1

15 Figure S1. Effect of Ag + concentration on the formation of AgNPs in the presence of pristine or M f -NOM under simulated sunlight irradiation. (a) pristine NOM, (b) >100 kda M f -NOM, (c) kda M f -NOM, (d) 10-0 kda M f -NOM, (e) -10 kda M f -NOM, and (f) < kda M f -NOM. The absorbance was the maximum absorbance at ~00 nm. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer (ph 8.0). 7 8 S1

16 Figure S1. Time-evolution of UV-vis spectra of pristine and M f -NOM under simulated sunlight. (a) pristine NOM, (b) >100 kda M f -NOM, (c) kda M f -NOM, (d) 10-0 kda M f -NOM, (e) -10 kda M f -NOM, and (f) < kda M f -NOM. Solution conditions: mg L -1 DOC pristine or M f -NOM in mmol L -1 borate buffer (ph 8.0). 7 S1

17 Figure S1. Effect of NOM concentration on the formation of AgNPs from Ag + in the presence of pristine or M f -NOM under simulated sunlight irradiation. The absorbance was the maximum absorbance at ~00 nm. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO, mmol L -1 borate buffer (ph 8.0). 7 S17

18 Figure S1. UV-vis spectra of the solution after h nm irradiation. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO, 0 mg L -1 DOC M f -NOM, mmol L -1 borate buffer (ph 8.0) >100 kda M f -NOM kda M f -NOM 10-0 kda M f -NOM -10 kda M f -NOM < kda M f -NOM Abs Wavelength (nm) S18

19 7 Figure S1. Effect of light quality on the formation of AgNPs from Ag + in the presence of pristine or M f -NOM under simulated sunlight irradiation. (a) pristine NOM, (b) >100 kda M f - NOM, (c) kda M f -NOM, (d) 10-0 kda M f -NOM, (e) -10 kda M f -NOM, and (f) < kda M f -NOM. The absorbance was the maximum absorbance at ~00 nm. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer (ph 8.0). 8 9 S19

20 Figure S17. UV-vis spectra of NOM solution in the absence or presence of Ca + (10 mg L -1 ). Solution conditions: 0. mmol L -1 AgClO, mg L -1 DOC pristine or M f -NOM, mmol L -1 borate buffer (ph 8.0). S0

21 Figure S18. Heating-induced Reduction of Ag + to AgNPs in pristine and M f -NOM solution at and 0 C. (a) C, and (b) 0 C. The absorbance was the maximum absorbance at ~00 nm. Background absorption of NOM was deducted from the prepared AgNPs solution. Solution conditions: 0. mmol L -1 AgClO and mg L -1 DOC pristine and M f -NOM in mmol L -1 borate buffer (ph 8.0). 7 8 S1

22 1 Figure S19. TEM images of the photo-induced AgNPs in Mf-NOM solution at 0 C. (a) >100 kda Mf-NOM, (b) < kda Mf-NOM. The scale bars are 0. µm. Solution conditions: 0. mmol L-1 AgClO and mg L-1 DOC Mf-NOM in mmol L-1 borate buffer (ph 8.0). 7 S