Thermally induced modification of the graphene oxide film on the tantalum surface

The interface chemical reactions, the deoxygenation and the overall thermal stability of the ex situ deposited graphene oxide (GO) thick film on the polycrystalline tantalum surface were studied by means of x-ray photoelectron spectroscopy (XPS) at room temperature and after annealing up to 600 degrees C. The evolution of the Ta-4f, C-1s and O-1s XPS core level spectra from the Ta/GO structure under study upon the increase of the annealing temperature was investigated with the reference to the uncovered Ta substrate surface. In the Ta/ GO structure the Ta relative atomic concentration was about 1% at room temperature due to the low porosity of the GO layer while the thermal desorption of the overlayer at the elevated temperatures was accompanied by an increase of the Ta concentration up to 47% at 500 degrees C. The C atoms relative concentration started decreasing after the annealing at 250 degrees C. accompanying the thermal desorption of the GO overlayer. The formation of the TaC compound starting from the 250 degrees C. annealing temperatures was determined. The relative oxygen concentration in the GO thick film was decreased upon increasing the annealing temperature accompanying both the thermal desorption of the GO material and the thermal reduction of the GO film. (C) 2016 Elsevier Ltd. All rights reserved.