Wavelength-Dependent Plasmonic Photobleaching of Dye Molecules by Large-Area Au Nanostripe Arrays

The development of clean light-harvesting platforms and technologies is crucial in view of the urgent energy and environmental global challenges. Plasmonic nanoparticles show great promise in light-harvesting applications, but their fabrication is typically constrained to small-area laboratory-scale methods or to highly polluting wet chemistry approaches that are not suitable for environmental applications such as waste water recycling. In this work, we propose a self-organized method to fabricate largearea (cm(2), industrially scalable up to m(2)) plasmonic templates. Ordered Au nanostripe arrays supported on cheap, nontoxic sodalime glass substrates are prepared, showing a tunable plasmonic response. We demonstrate enhanced photochemical reactivity and photobleaching of highly polluting methylene blue molecules promoted by this self-organized plasmonic platform. We investigate this effect by tailoring the spectral overlap between the molecule absorption band and the plasmon resonance and by tuning the monochromatized excitation wavelength. This kind of study is completely lacking in the literature for big molecules with optical absorption bands in the visible range. We demonstrate the dominant role of plasmon-enhanced near-field optical effects over hot-carrier injection in amplifying photodissociation of colored dye molecules, thus paving the way to the engineering and optimization of light-harvesting platforms for waste water treatment, dye molecule sensing devices, and a broad range of other light-harvesting applications.