Nanostructural characteristic and electrochemical performance of hydroxy graphene oxide@Ag–nanoparticles coating: Combined TEM and DFT calculation

Abstract

A hydroxy graphene oxide (HGO)@Ag–nanoparticles (Nps) coating was fabricated on Ti6Al4V alloy by nanosecond laser direct energy deposition (LDED). The physical and chemical characteristics of obtained coating were performed using a transmission electron microscope (TEM), X–ray photoelectron spectroscopy (XPS), Fourier transform infra–red (FTIR) spectrometer and Raman spectroscopy. The electrochemical performances of HRO@Ag–Nps coating in 0.9% NaCl and 10% bovine serum albumin (BSA) solutions were investigated using an electrochemical workstation, and the electrochemical mechanism was discussed by the density functional theory (DFT) calculation. The results show that the pore resistance of HGO@Ag–Nps coating in 10% BSA solution is larger than that in 0.9% NaCl solution, presenting the higher corrosion resistance. The combined nanostructure between the cysteine of HRO@Ag–Nps coating and the methylene of BSA solution is caught by TEM, and the composite model of DFT and electrochemical impedance spectroscopy (EIS) verify that the BSA nano–layer is formed on the coating surface with the covalent hydrogen bond. Moreover, the result of DFT calculation also demonstrates that the band gap of HGO@Ag–Nps coating in 10% BSA solution tends to 0 eV, which improves its electrochemical performance in 10% BSA solution.