Figure 3. XPS spectra of Pd/RGO composite: (a) XPS full spectrum of Pd/RGO and (b) Pd spectrum.

XPS full spectrum analysis indicated only palladium, oxygen, nitrogen and carbon, the absence of phosphorus indicating that no TOP molecules are on the surface of the Pd NPs and RGO. The XPS spectrum of the Pd spectrum showed double peaks with binding energies at 335.1 eV and 340.4 eV, corresponding to Pd_3d5/2 and Pd_3d3/2, respectively.