Selective Deposition of Silver Nanoparticles onto WO₃ Nanorods with Different Facets: The Correlation of Facet-Induced Electron Transport Preference and Photocatalytic Activity

WO₃ nanorods with a regular hexagonal morphology and different exposed facets were fabricated by hydrothermal treatment, and then Ag nanoparticles (Ag NPs) selectively deposited onto hexagonal WO₃ nanorods with different facets were also successfully synthesized through an in situ photoreduction method. The prepared samples were characterized by various analytical techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectra, and so on. The results illustrated that the intrinsic nature of charge separation on the {001} facets of WO₃-110 nanorods and the surface plasmon resonance (SPR) effect both contribute to the enhancement of visible-light absorption and the decrease of the recombination of the photogenerated electron-hole pairs. For comparison, Ag/WO₃-110 catalysts with dominant exposed {001} facets exhibited much better photocatalytic activity than that of Ag/WO₃-001 with a high percentage of exposed {100} and {010} facets for the degradation of organic pollutants (including rhodamine B, methyl orange, and so on) under the visible-light irradiation. In addition, the underlying photocatalytic reaction mechanism was further investigated by the controlled experiments using radical scavengers.