UV-Assisted Reduction of Graphite Oxide to Graphene by using a photoinitiator

Bing Xue1, Yingquan Zou1,* Yuchun Yang2

1, Chollege of Chemistry, Beijing Normal University, Beijing, 100875, China

2, Shenzhen Rongda photosensitive Science and Technology Co., Ltd, Shenzhen, 518103, China

*Corresponding author: [email protected]

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In this work, before photoinitiator GR-FMT was decided as the reductant, three commonly used free radical photoinitiators (GR-FMT, GR-819 and GR-TPO) are choose to investigate the reduction properties. The absorption spectra of the three photoinitiators indicate that all of them have the absorption at 395nm wavelength (Figure S1a). Furthermore the XRD patterns of the products obtained at the three photoinitiators in methanol, ethanol, and acetone solvents are conducted (supporting Information, Figure S1b). The spectra shows that only GR-FMT presents the broad peak of reduced graphene oxide and the highest peak belongs to the products by dispersing GR-FMT in ethanol solvent.

Figure S1. a: The absorption spectra of GR-FMT, GR-819 and GR-TPO dissolved in ethanol. b:

XRD spectra of the products of GR-FMT, GR-819 and GR-TPO with 4mg GO irradiated for 10 min in 20ml methanol, ethanol, and acetone solvents.

In addition, the pictures for different amount of GR-FMT (40, 80, 120mg) addition with 4mg GO and 20ml ethanol after irradiation are detected (Figure S2). Picture A exhibits the GR-FMT in ethanol and irradiated in the dark environment for 10min. Picture B shows the 40mg GR-FMT addition in the suspensions from which we can observe the black precipitation in the bottom after 10min irradiation, while the supernatant liquid is not as transparent as picture C (with 80mg GR-

FMT addition). This is due to the insufficient amount of GR-FMT, and the supernatant liquid contains the unreacted graphene oxide. In contrast, the yellow precipitant is appeared with 120mg

GR-FMT addition in picture D. Among the four samples, only picture C displays the transparent supernatant liquid and pure black precipitation.

Figure S2. The pictures of GR-FMT, GO with different amount of GR-FMT addition (40, 80 and

120mg) irradiated by 395nm UV-light in ethanol solvent for 10min.

In order to figure out the yellow precipitation, XRD patterns for pristine GR-FMT powder and the dried yellow precipitation are detected (supporting Information, Figure S3). The identical peak position of the two samples can be obviously observed which means the yellow precipitation is belonging to the unreacted GR-FMT. This phenomenon also demonstrates the free radicals of GR-

FMT can be recombined after UV-irradiation. This indicates the photoinitiator GR-FMT is stable in ethanol solvent, which will be participate once the additional quantity used.

Figure S3. The XRD patterns of pristine GT-FMT powder and the dried precipitant obtained in

GO-ethanol solution with excessive GR-FMT addition under 395nm light irradiation.