Developing titania-hydroxyapatite-reduced graphene oxide nanocomposite coatings by liquid flame spray deposition for photocatalytic applications

Nanostructured titania has been extensively investigated for photocatalytic applications. Persistent challenge yet is how to effectively promote adhesion of microorganisms on the material surface for consequent enhanced photocatalytic disinfection. Here we report fabrication and characterization of titania-based nanocomposite coatings with addition of hydroxyapatite-reduced graphene oxide (HA-rGO). The nano features of TiO2, HA, and rGO were well retained during liquid flame spray deposition. Photocatalytic activities of the coatings were examined by degradation of methylene blue and sterilization testing of Escherichia coli bacteria. Addition of HA-rGO effectively increased the specific surface area of the coatings and markedly enhanced adherence of the bacteria for subsequent extinguishment. The TiO2-10 wt.% (HA-rGO) coating showed the best photocatalytic performances and further overloading of HA-rGO resulted in enwrapping of TiO2 particles, resulting in deteriorated degradation activity. The results give clear insight into fabrication of novel photocatalytic nanocomposites by suspension thermal spray route for enhanced performances.