Fig. 5: Study of rGO chemical composition by XPS.

a Micro-XPS mapping illustrates the spatial distribution of the C/O ratio on a GO film following 405 nm laser irradiation. The dashed circles indicate the location of the laser-irradiated spots at laser powers of 50, 70, 600 µW, 1.2 mW, 7.4 mW, and 13.5 mW from left to right. The color gradient from blue to red indicates an increase in the C/O ratio, a direct measure of GO reduction. b Survey XPS spectra differentiate between untreated GO (blue) and laser-reduced GO at 405 nm 1.2 mW and 7.4 mW (green and red respectively). The rGO spectrum shows a C1s peak larger than the O1s peak, indicating a decrease in oxygen content consistent with reduction. The data has been offset. c–e High-resolution C1s spectra reveal the detailed chemical structure changes from c GO to rGO with different laser powers of d 1.2 mW and e 7.4 mW. The GO spectrum shows peaks associated with various oxygen-carbon bonds. In contrast, the rGO spectrum displays a substantial rise in the C = C sp² bond peak, suggesting the restoration of the graphitic domain and a reduction in peaks associated with oxygen-containing functional groups due to laser irradiation. Source data are provided as a Source Data file.