NBEXP0013

=NBEXP0013 — Test of UV-induced reduction of Graphene Oxide=

=Objective=

To determine whether graphene oxide can be reduced using UV illumination alone.

=Procedure=


 * 1) Add 100mg to 20ml of ethanol in a 40mL sample tube. Seal tube with rubber septum.
 * 2) Illuminate tube under UV for ~6 hours with Ar bubbling and stirring
 * 3) Filter solution (Watson 41 ashless) & wash with distilled water 3 times
 * 4) Dry sample in vacuum overnight
 * 5) Obtain raman spectrum of specimen. Wavelength 514.5nm, from 800cm-1 to 2200cm-1, along with spectra of original GO powder and graphite precursor
 * 6) Perform baseline correction if necessary.

=Expected outcome=

If UV does indeed reduce graphene oxide to graphene, then there should be a relative shift in the D & G band peaks of the raman spectra. The G band should narrow and the peak shift from ~1590 to ~1580cm-1. Likewise the D band intensity should decrease.



=Results=



[|NBEXP0013 — Raman data]




 * || D band || G band ||
 * Graphite || 1347.47 || 1572.47 ||
 * Graphene oxide || 1352.04 || 1585.7 ||
 * Irradiated graphene oxide || 1351.85 || 1589.4 ||

=Discussion=

Raman results show that oxidation was successful for the following reasons:
 * Broadening of D & G peaks due to the addition of hydroxyl and epoxy groups
 * Increase of D band intensity relative to G band due to increased disorder in the graphene oxide lattice
 * The G band shift from 1572 to 1585 cm-1 due to increased numbers of isolated carbon double bonds in disordered GO (10.1021/nl071822y)

UV irradiation does not seem to have reduced graphene oxide. The D & G relative intensities are the same and the peaks remain broad. There is a shift in the G band from 1585 to 1589cm-1, which may indicate //increased// oxidation, or, more likely, the laser beam was on a slightly more disordered graphene specimen.

The observation that the solution looked darker/blacker after irradiation can be explained by the increased concentration of graphene oxide as a result of the loss of solvent to evaporation during illumination.

=Conclusion=

UV illumination does not reduce graphene oxide. Graphene oxide remains stable under prolonged UV illumination.

=Log=

2009-10-15
13:55 Added 101mg of GO to 20ml ethanol (absolute) in 50mL sample tube, capped w' rubber septum & parafilm. 14:00 Took photo of sample 14:06 Put sample under UV with stirring and Argon bubbling. 15:00 Septum had come off tube. Replaced septum, secured with scotch tape and added paper cylinder around septum/tape to reflect UV & prevent degradation of septum/tape. 17:46 Removed soln from UV & took picture. Soln appeared darker than before irradiation 17:57 Filtered solution (Whatman 41, ashless paper) & washed 3 times with MilliQ water 18:18 Put filter paper w' powder in vacuum chamber

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