Waveguide‐Plasmon Polariton Enhanced Photochemistry

One key process in plasmon‐enhanced photocatalysis is the transfer of hot charge–carriers from metal nanostructures into photocatalytically active materials. This process is secondary to the initial step of light absorption by the metal nanostructures. Light absorption in these structures can be controlled by designing complex geometries with tailored optical cross‐sections. Here, a study on one of the simplest nanostructures exhibiting plasmon resonances is presented: 1D gratings of metal wires. Results on the effect of the periodicity of these arrays are presented on the resonant absorption of light and on the hot charge–carrier transfer to a supporting TiO₂ thin film. This charge transfer process is monitored by following the photocatalytic decomposition of small organic molecules in solution. Strong enhancements in the rate of decomposition are found that exhibit a correlation with the measured optical extinction spectra of the plasmonic nanostructures.