es5047155_si_001.pdf (954.54 kB)
Photochemical Transformation of Graphene Oxide in Sunlight
journal contribution
posted on 2015-03-17, 00:00 authored by Wen-Che Hou, Indranil Chowdhury, David G. Goodwin, W. Matthew Henderson, D. Howard Fairbrother, Dermont Bouchard, Richard G. ZeppGraphene
oxide (GO) is promising in scalable production and has
useful properties that include semiconducting behavior, catalytic
reactivity, and aqueous dispersibility. In this study, we investigated
the photochemical fate of GO under environmentally relevant sunlight
conditions. The results indicate that GO readily photoreacts under
simulated sunlight with the potential involvement of electron–hole
pair creation. GO was shown to photodisproportionate to CO2, reduced materials similar to reduced GO (rGO) that are fragmented
compared to the starting material, and low molecular-weight (LMW)
species. Kinetic studies show that the rate of the initially rapid
photoreaction of GO is insensitive to the dissolved oxygen content.
In contrast, at longer time points (>10 h), the presence of dissolved
oxygen led to a greater production of CO2 than the same
GO material under N2-saturated conditions. Regardless,
the rGO species themselves persist after extended irradiation equivalent
to 2 months in natural sunlight, even in the presence of dissolved
oxygen. Overall, our findings indicate that GO phototransforms rapidly
under sunlight exposure, resulting in chemically reduced and persistent
photoproducts that are likely to exhibit transport and toxic properties
unique from parent GO.