Applied Nanophotonics, Liquid Crystals and Biomedical Optics

Low solar light absorption and high electron-hole pair recombination are still the main challenges for solar energy conversion. Here, we design a plasmonic nanoparticle (NP)-film with a unique structure combining the advantages of a Au NP and film, which exhibits strong broadband absorption from the visible to near-infrared (NIR) wavelength range. In addition, the high density of sub-1 nm inter-particle gaps in the Au NP-film supports electromagnetic field enhancement of several orders of magnitude that greatly promotes the generation and separation of electron-hole pairs. Accordingly, the plasmonic NP-film-assisted photocatalyst (TiO₂/90Au/TiO₂) leads to an 88-fold increase in the photocurrent density at 0.75 V vs. RHE in 25% methanol solution under visible-NIR light irradiation (λ > 420 nm) compared to a TiO₂ film, which is higher than those of the ever reported Au/TiO₂ photocatalysts in the entire visible-NIR range. Our finding indicates a promising way to explore full solar spectrum photocatalysts, which can be easily extended to other energy conversion applications.