Plasmon-induced visible light absorption arising from edge-interfaces of titanium-oxides nanocomposites

The efficient utilization of visible light on wide-bandgap metal-oxides is a long-term goal but is still a grand challenge for plasmon-driven chemistry. The plasmon-induced concentration of photons in adjacent materials provides a strategic pathway to extend the light-harvesting regime to sub-bandgap. With the abundant edge-spots in surface nanostructures, here, we report that the titanium-oxides nanocomposites composed of the metallic titanium coupled with its oxides exhibit significant resonant visible absorption. The experimental characterizations with computational analyses demonstrate that the excited plasmon resonance at edge-interfaces results in the unique visible absorption band. Localized field-enhancement, charge-scattering, and hot-electrons effects conclusively confirm that the visible absorption is derived from the plasmon resonance, rather than the narrowing of bandgap or energy levels of impurities or defects. The plasmon-induced absorption effectively enhances the separation and transfer of photogenerated charge carriers leading to improved photoactivity. Our results help to advance titanium-oxides nanocomposites towards plasmonic chemistry in the visible-light region and highlight a potential general route to harnessing photons beyond the bandgap limitation based on plasmonic metal-oxides nanocomposites.