Au thorn-decorated TiO2 hierarchical microspheres with superior photocatalytic bactericidal activity under red and NIR light irradiation

Herein, we fabricated a novel surface plasmon resonance (SPR) photocatalyst Au(T)-TiO2(MS) by anchoring Au thorns on TiO2 hierarchical microspheres (MS). It was found that the flower-like TiO2 microspheres with a size of ~800 nm consist of many lamellar petals and the Au thorns with length of dozens of nanometers were anchored on TiO2(MS). By analyzing the DRS, PL spectra, transient photocurrents and electrochemical impedance spectra, it was disclosed that Au thorns not only respond to visible and NIR light but also effectively promote the separation of photogenerated charge carriers in TiO2(MS). The photocatalytic inactivation of E. coli K12 indicated that Au(T)-TiO2(MS) displayed excellent bactericidal activity and stability under red and NIR light irradiation. Due to the special structure of Au(T)-TiO2(MS), it can produce reactive species outside and within bacteria, both of which work together responsible for the inactivation of E. coli K12. The EPR spin-trap measurements with DMPO and reactive species trapping experiments revealed that all of h+, •OH and •O2− are produced over Au(T)-TiO2(MS), while •O2− and h+ are the main reactive species for bacterium inactivation.