A Microorganism Bred TiO₂/Au/TiO₂ Heterostructure for Whispering Gallery Mode Resonance Assisted Plasmonic Photocatalysis

The TiO₂/Au nanostructure has been acknowledged as one of the most classic visible-light active photocatalysts due to the surface plasmon resonance (SPR) of Au nanoparticles. In many cases, the SPR effect only features weak visible light absorption in conventional TiO₂/Au nanostructures. Here, we demonstrate a design of TiO₂/Au/TiO₂ with a combination of whispering gallery mode (WGM) resonances and SPR for efficient visible-light-driven photocatalysis. Escherichia coli (E. coli) were used as natural reactants as well as a template to construct an E. coli-like TiO₂/Au/TiO₂ nanostructure. Using numerical simulations, we show that the E. coli-like TiO₂ capsule acts as the WGM resonator to interplay with the SPR effect of the Au NPs on TiO₂ surface, which leads to a significant increase of visible light absorption and the local field enhancement at the Au–TiO₂ interface. Accordingly, with the synergistic effect of WGM and SPR, the E. coli-like TiO₂/Au/TiO₂ nanostructure exhibits enhanced photocatalytic activity in the visible range. Our work reveals a promising bioapproach to a design highly visible light active plasmonic photocatalyst.