Strong Visible Light Absorption and Abundant Hotspots in Au-Decorated WO₃ Nanobricks for Efficient SERS and Photocatalysis

Abstract

Metal/semiconductor hybrids show potential application in fields of surface-enhanced Raman spectroscopy (SERS) and photocatalysis due to their excellent light absorption, electric field, and charge-transfer properties. Herein, a WO 3 -Au metal/semiconductor hybrid, which was a WO 3 nanobrick decorated with Au nanoparticles, was prepared via a facile hydrothermal method. The WO 3 -Au hybrids show excellent visible light absorption, strong plasmon coupling, high-performance SERS, and good photocatalytic activity. In particular, on sensing rhodamine B (RhB) under 532 nm excitation, bare WO 3 nanobricks have a Raman enhancement factor of 2.0 × 10 6 and a limit of detection of 10 −8 M due to the chargertransfer property and abundant oxygen vacancies. WO 3 -Au metal/ semiconductor hybrids display a largely improved Raman enhancement factor compared to pure Au and WO 3 components owing to the synergistic effect of electromagnetic enhancement and charge transfer. The Raman enhancement factor and limit of detection are further improved, reaching 5.3 × 10 8 and 10 −12 M, respectively, on increasing the content of Au to 2.1 wt %, owing to the strong plasmon coupling between the Au nanoparticles. Additionally, the WO 3 -Au hybrids also exhibit excellent photocatalytic activity toward degradation of RhB under visible light irradiation. WO 3 -Au (2.1 wt %) possesses the fastest photocatalytic rate, which is 6.1 and 2.0 times that of pure WO 3 nanobricks and commercial P25, respectively. The enhanced photocatalytic activity is attributed to the strong plasmon coupling and the efficient charge transfer between Au and WO 3 nanobricks. The as-prepared materials show great potential in detecting and degrading pollutants in environmental treatment.

Ultrathin and Conformal TiOx Overlayers on WO3 Photoelectrodes for Simultaneous Surface Trap Passivation and Heterojunction Formation

“…The films were further analyzed by Raman spectroscopy, and the results are displayed in Figure S2. All samples exhibit peaks at 133, 185, 273, 292, 325, 718, and 805 cm –1 , which highly match those of WO 3 . Moreover, this result indicates that the derivatives of Ti-DAL on WO 3 films are either amorphous or negligible.…”

“…All samples exhibit peaks at 133, 185, 273, 292, 325, 718, and 805 cm −1 , which highly match those of WO 3 . 30 Moreover, this result indicates that the derivatives of Ti-DAL on WO 3 films are either amorphous or negligible. The samples were prepared by directly dropping a Ti-DAL solution onto glass, followed by the O 2 plasma treatment to facilitate easy identification of Ti-DAL derivatives.…”

Plasmonic Modification of Epitaxial Nanostructures for the Development of a Highly Efficient SERS Platform

“…To conclude, tungsten(VI) oxide-based nanostructures are a promising alternative for Raman signal amplification and could contribute to the development of more versatile SERS substrates. However, so far, SERS measurements are usually made using combinations of this oxide with silver or gold nanoparticles [51,[86][87][88]. Hollow WO 3 nanospheres showed high SERS activity; the EF was estimated to be 1.6 × 10 6 [83], while decorating WO 3 nanoflakes with silver nanoparticles allows for the increase in EF to 3.9 × 10 8 , which corresponds to a 10 −10 M detection limit [86].…”