Photocatalytic thin films based on Au nanoparticles covered by iron oxyhydroxides by hydrothermal process

The use of ultrathin nanohybrid films in photocatalytic applications to decompose pollutants is a desirable and effective approach for industrial and practical purposes. In this study, ultrathin films composed of Fe2O3 oxyhydroxides with Au nanoparticles (NPs; Au–FeOOH) were prepared by Au evaporation deposition, a hydrothermal process, and thermal annealing. Transmission electron microscopy, elemental mapping, and X-ray photoelectron spectroscopy studies confirmed the attachment of the FeOOH matrix to the Au nanoparticles. Au–FeOOH thin films exhibited outstanding photodecomposition ability toward rhodamine 6G in a 0.5 µM aqueous solution under artificial light illumination (120 min; 1000 W m−2); such performance is the best reported thus far for Fe2O3 thin films. The superior photocatalytic activity of the Au–FeOOH nanohybrid thin films is attributed to their broad absorption encompassing the deep ultraviolet-to-near infrared regions and efficient charge transfer between the Au NPs and FeOOH NPs.