Synergistic enhancement of photocatalytic antibacterial effects in high-strength aluminum/TiO2 nanoarchitectures

Unlike gold and silver, aluminum shows a localized surface plasmon resonance (LSPR) over a wide spectral range from ultraviolet (UV) to the visible region. Herein, we demonstrate a new process to optically couple TiO2 nanotubes (NTs) with a high-strength aluminum substrate, to achieve a synergistic enhancement of photo catalytic antibacterial effects through controlled LSPR of aluminum. The high-strength aluminum substrate was produced by tubular channel angular pressing (TCAP). Their LSPR was tailored through the formation of superficial nano-concave arrays (NCAs) with desired concave diameters. A layer of aligned TiO2 NTs was fabricated on the surface of aluminum nano-concave arrays (Al NCAs) by anodization of a thin film of titanium. When the diameter of Al NCAs reached similar to 80 nm, a strong LSPR near the optical bandgap of TiO2 NTs was detected, whereby a synergistic antibacterial effect to Escherichia coli (E. coli) was observed through the coupling of TiO2 NTs photocatalysis and LSPR effect of Al NCAs (80 nm) in the UV-A range. The TiO2 NTs/Al NCAs hybrid surface showed excellent resistance against scratch. The results presented here may open a door for the further development of self-cleaning medical tools based on the decontamination strategies.