Effect of synthesis methods of Co-modified TiO2 in its photocatalytic and bactericidal activity

It is well-known that a given material's synthesis method can change its catalytic properties. In this work, we demonstrated that Co-modified TiO2 (TiCo) showed photocatalytic activity and bactericidal for water decontamination. The nanomaterials with high cobalt content were obtained by three synthesis methods, namely polymeric precursors (PP), sonochemical (US), and microwave-assisted hydrothermal (MW). The PP and US methods produced a mixture of rutile and cobalt titanate (CoTiO3) or anatase and CoTiO3, respectively, while the MW method produced pure anatase. We applied Rietveld refinement to quantify the different crystalline phases, and the cobalt was quantified by EDX and atomic absorption spectrometry (AAS). It was confirmed that the cobalt doping level depends on the crystalline phase obtained and improves the visible light absorption. Pathogenic microorganisms and organic pollutants remediation were investigated in detail using heterogeneous photocatalysis and mass spectrometry (MS) analysis, proving that the nanomaterials' nature influences the action mechanisms under the light. The photocatalyst synthesized from the MW method showed the best results. It was possible to demonstrate that the photocatalytic mechanisms proposed, and bactericidal activity depends on the structure of the nanomaterial obtained.