SUPPORTING MATERIAL

Photochemical stability and reactivity of Graphene Oxide

M. Minella1, M. Demontis1, M. Sarro1, F. Sordello, P. Calza1*, C. Minero1

1 Department of Chemistry and NIS Center, University of Torino, Via P. Giuria 5, Torino 10125, Italy http://www.environmentalchemistry.unito.it.

* Corresponding author. Fax +39-011-6705242; E-mail: .

Table 1-SM. Attribution of the main ATR-FTIR signals recorded on the pristine GOs synthesized.

IR signal, cm–1 / Vibrational mode
3500-3300 / O–H stretching of the hydroxyl groups and of the adsorbed water
» 1720 / Carbonyl group Stretching (C=O)
» 1620 / Vibrational mode of sp2 carbon atoms in aromatic rings;
ν2 bending mode of adsorbed water
1300-1350 / C–OH stretching
1220 / Breathing vibration from epoxy
Groups
» 1040 / C–O stretching
990 / Vibration mode of epoxy, ether and peroxy groups
A / B

Fig. 1-SM Emission spectra of (A) the TLK 40W/05 (UV-Vis) fluorescent lamps (Phillips, Eindhoven, Nederland); (B) the Sylvania H44GS-100 low pressure Hg vapor lamp.

Fig.2-SM a) Picture of the irradiation system with the three UV-Vis lamp set; b) scheme of the cells used for the photochemical experimentys.

(1)
(2)

Fig. 3-SM Pictures of the cells containing the GO (30 mg C dm–3) suspensions under air (1) and under nitrogen (2) after different irradiation times: a) before irradiation, b) after 1 day, c) after 4 days; d) after 14 days.


Fig.4-SM XPS spectra on pristine GO powder (a) and Go following 1 day of irradiation (b).

Fig.5-SM Ion chromatograms of filtered suspensions of GO after different irradiation time (0, 0.5, 1, 2, 3, 4, 7 and 14 days) under air (a) and under N2 (b). The retention times for the identified anions are: 3.6 min acetate, 4.0 min formate, 5.0 min chloride, 8.5 min phosphate and 9.6 min sulphate.

Fig.6-SM Pictures of the GO particles collected on the surface of the 0.45 μm filtering membrane before irradiation (a) and after 3 days of irradiation under air (b). Note that no significant difference can be individuated at a glance between the samples of GO collected after irradiation under air or under N2.

(A)
(B)

Fig.7-SM ATR-FTIR spectra of the GO particles obtained after different irradiation times under air (A) and under N2 (B) collected on the filtering membrane. From the bottom to the top the spectra of the membrane alone and of the samples obtained at increasing irradiation time (0, 0.5, 1, 2, 3, 4 and 7 days)