In situ synthesis of three dimensional graphene-hydroxyapatite nano powders via hydrothermal process

In this study, in situ formation of three dimensional graphene-hydroxyapatite using graphene oxide, calcium nitrate tetra hydrate, and diammonium hydrogen phosphate solutions in a chemical synthesis system was investigated. First, the solutions were mixed and calcium phosphate was precipitated on graphene oxide sheets followed by performing a hydrothermal method at 180 °C, 2.2 MPa, pH = 11, and 6 h. The latter process resulted in the formation of three dimensional graphene while it was coated on hydroxyapatite nanorods. The synthesized powders were characterized in two steps for calcium phosphate-graphene oxide powders before hydrothermal process and three dimensional graphene-hydroxyapatite powders after hydrothermal process with Fourier-Transform Infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), and Raman spectroscopy. The results of XRD and FTIR analysis showed that in the first step, di-calcium phosphate dehydrates were formed on graphene oxide sheets and converted to hydroxyapatite after the hydrothermal process. Raman spectroscopy analysis and FTIR confirmed that graphene oxide has been reduced in the hydrothermal process. Also, microscopic images confirmed the three-dimensional structure of graphene after hydrothermal process. Finally, the results showed that the hydrothermal method leads to the formation of a high crystalline hydroxyapatite nanorods that cover the surface of the three dimensional graphene. •The hydrothermal process led to the reduction of graphene oxide.•The hydrothermal process resulted in the synthesis of hydroxyapatite nano-rods.•Graphene oxide sheets were assembled together and a 3D rGO structure was formed.•In hydrothermal conditions, the hybrid powder of 3DG coated with hydroxyapatite nano rods was synthesized.