2012 Volume 10 Pages 513-517
In order to determine the local structure of carbon sp2 clusters in chemically modified graphene oxide (GO) flakes, their luminescence was analyzed, using near-infrared photoluminescence (NIR PL) spectral imaging. GO flakes emit a broad PL spectrum of wavelengths of 800 to 1400 nm, indicating that they contain sp2 clusters, whose size is theoretically estimated to be in the 1.3 to 2.3 nm region. The size distribution of such sp2 clusters is fairly uniform at different positions and for different numbers of layers of GO, at the spatial resolution of NIR PL image (5μm). The analysis by transmission electron microscopy directly confirmed the existence of such sp2 clusters and the estimated size of the sp2 clusters was widely ranged from 0.5 to 4 nm. The effect of the GO reduction to the local structure of carbon sp2 clusters was also studied and it was found that the NIR PL intensity decreased as the reduction progressed and that there was no large spectral shift. [DOI: 10.1380/ejssnt.2012.513]
