Optical enhancement of plasmonic activity of catalytic metal nanoparticles
Noble metals have recently been shown to drive direct photocatalytic reactions in which they both provide hot electrons via the localized surface plasmon resonance (LSPR) and the catalytically active site. Catalytic reactions are also possible on other metals such as platinum or rhodium which, however, exhibit rather poor plasmonic properties (low field enhancements, low resonance quality factors) and their LSPR for nanometer sized particles occurs in the UV, an unfavourable effect when considering sunlight as a photon source. By coupling the LSPR response of catalytic metal nanoparticles to that of a silver nanoparticle we can excite a hybridized resonance that matches the spectral characteristic of the light source and light absorption in the catalytic metal is enhanced by up to one order of magnitude. This is shown for a number of catalytic metals and is further discussed for model Drude and Drude–Lorentz materials. These results provide guidelines for designing catalytic metal nanostructures which absorb the solar spectrum very efficiently.