Synthesis and Electrochemical Characterization of TiO2/g-C3N5 Coated 316L Stainless Steel for Orthopedic Applications

Abstract

This study investigates the effect of varying amounts of nitrogen-rich carbon nitride (g-C3N5) incorporated into titanium dioxide (TiO2) coatings on 316L stainless steel (316LSS). The TiO2/g-C3N5 coatings were tested in simulated body fluid (SBF) to assess their performance for orthopedic applications. TiO₂ was prepared using the sol-gel method, while g-C3N5 was synthesized through thermal polymerisation. The crystal structure, purity, and chemical composition of the TiO2/g-C3N5 (TiCN) composites were confirmed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman analysis. The surface morphology of the coated samples was characterised using Scanning Electron Microscopy (SEM). In contrast, surface roughness was measured with Atomic Force Microscopy (AFM), revealing a porous film with an average particle size of 25 to 100 nm was coated over 316LSS. A fourfold increase in corrosion resistance was evaluated through Open circuit potential (OCP), Potentiodynamic polarisation, and Electrochemical impedance spectroscopy (EIS). The in vitro test revealed the enhanced growth of a hydroxyapatite layer on the coated TiCN. The elemental composition of calcium and phosphate ions present in the hydroxyapatite (HAP) deposition was confirmed using Raman spectroscopy. The results suggest that the TiCN coated 316LSS was a promising material for biomedical applications.