Construction of S‐Scheme Heterojunction by TiO ₂ / rGO Assembled With g‐ C ₃ N ₄ for Efficient Visible‐Light‐Driven Antibacterial Activity of Bone Scaffold

ABSTRACT The low photogenerated charge carriers and quick complex annihilation of titanium dioxide (TiO ₂ )/rGO composite leading to an unsatisfactory photocatalysis antibacterial effect limit its application in the bone scaffold. Herein, graphitic carbon nitride (g‐C ₃ N ₄ ) was assembled with TiO ₂ /rGO via a solvothermal method for enhancing the photocatalysis antibacterial properties of poly (lactic acid) (PLLA) bone scaffold prepared via selective laser sintering. The results revealed that g‐C ₃ N ₄ expanded the light absorption range of TiO ₂ /rGO from blue‐violet light to visible light, resulting in the composites having a narrower band gap and producing more photoinduced charge carriers. More importantly, an S‐scheme heterojunction was formed between g‐C ₃ N ₄ and TiO ₂ , which promoted the recombination of the electrons in the conduction band of TiO ₂ and the holes in the valence band of g‐C ₃ N ₄ . Meanwhile, rGO with excellent electrical conductivity reduced the interfacial charge transfer resistance and enhanced charge transfer efficiency, thus further avoiding the recombination rate of electrons and holes, whether TiO ₂ or g‐C ₃ N ₄ , and enhancing the photocatalytic properties. Consequently, the holes in the valence band of TiO ₂ and the electrons in the conduction band of g‐C ₃ N ₄ possessed high oxidation and reduction capacity, which oxidized H ₂ O and reduced O ₂ in the microenvironment, respectively, and generated lots of reactive oxygen species. In vitro antibacterial experiments indicated that the PLLA/TiO ₂ /g‐C ₃ N ₄ /rGO scaffold showed a better antibacterial effect, with the bacteriostasis rates of E. coli and S. aureus being 99.1% and 98.9%, respectively. In addition, cell adhesion and fluorescence results indicated that the scaffold had good biocompatibility and could provide a suitable microenvironment for the growth and proliferation of cells.