Wang et al. Nanoscale Research Letters 2012, 7:161 http://www.nanoscalereslett.com/content/7/1/161 Page 3 of 7 Figure 1 Schematic illustration of preparation of E-rGO and C-rGO. Raman spectroscopy is an effective tool to character- ize the structural change of GO after reduction. In Fig- ure 2, the peak at around 1,600 cm-1 is assigned to the E2g mode, i.e. G band [39], and the peak at 1,350 cm-1 is corresponding to the D band [38]. Both GO and rGO have these two bands. But the intensity ratio of D/G increased after the reduction (curves b, c, and d in Figure 2), suggesting a decrease in the average size of the in-plane sp2 domains upon the reduction of the exfoliated GO and rGO was obtained [39]. Impor- tantly, it should be noted that the G band shifted dur- ing the Raman measurement of E-rGO (curves c and d). For the fresh reduction product of E-rGO, it is found that G band shifted from 1,600 to 1,587 cm-1 (curve c) compared with GO. But after E-rGO has been kept in air for 1 day, the G band shifted back to Figure 2 Raman spectra of ITO-APTES-GO and C-rGO and fresh reduction of ITO-APTES-E-rGO. Raman spectra of (a) ITO-APTES-GO, (b) ITO-APTES-C-rGO, (c) fresh reduction of ITO-APTES-E-rGO, and (d) ITO-APTES-E-rGO after kept in air for 1 day. Laser, 633 nm.