Fig. 3

C 1 s XPS spectra (hν = 1253.6 eV) collected on GO thin film deposited on Ni(100 nm)/Si and annealed in air for 15 min at the temperatures 50, 120, 180, and 250 °C (a–d). The different components related to various chemical shifts of carbon bonds are indicated. The relation of areas of the C1s to O1s XPS peaks (e) and the atomic percentages of different carbon bonds identified by XPS as a function of annealing temperature (f)