부산대학교 도서관

In the present work, primarily graphite oxide (gO) was synthesized utilizing the Modified Hummers method and its further ultrasonication for 2, 4, 6 and 8 h resulted in the formation of graphene oxide (GO). Scanning Electron Microscopy and Atomic Force Microscopy reveal the formation of GO sheets with laminar morphology. The increase in the ultrasonication time resulted in exfoliation of GO sheets. X-ray Diffraction spectra confirms the gO oxidation and the GO formation with a lower shift of the (001) plane from 11.3° to 10.7°. Fourier-transform infrared spectroscopy indicates that all samples possess similar functional groups, whereas an increase in the ultrasonication time widens the O–H band and increases the C–H band intensity indicating GO reduction. Raman shows the intensity ratio of D and G band (ID/IG) decreases, and the in-plane crystalline size increases from 10 to 45 nm which can be attributed to defects caused by gO oxidation and partial conversion of sp2 to sp3 hybridization. All the samples were tested for their sensing responses at different concentrations (100, 200, 400, 600, 800 and 1000 ppm) of CO2 at 100 °C. Highest sensing response ~ 81% was recorded for samples ultrasonicated for 8 h. This is attributed to the CO2 interaction with C-H functionalized groups of GO. The principal structural and morphological properties of all samples and their effect on CO2 sensing properties were discussed in detail. [ABSTRACT FROM AUTHOR]