The use of tunable optical absorption plasmonic Au and Ag decorated TiO₂ structures as efficient visible light photocatalysts

Exploring solar-excited heterogeneous photocatalysts by taking advantage of surface plasmon resonance (SPR) has drawn growing research attention. As it could help to pave the way for global sustainable development. The decoration of TiO₂ particles with noble metals possessing SPR effects is regarded as one of the most effective solutions. The perfect match of the SPR absorption band with the spectrum of incident light is an essential factor for plasmonic enhancement. However, modifying with sole noble metal is often limited as it tunes wavelength of only several nanometers. To overcome this drawback, an alternative approach can be offered by decoration with more than one noble metal. For instance, Au-Ag co-decoration displays greatly adjustable, composition-dependent SPR agent over a broad range of the visible light spectrum (ca. from 415 to 525 nm). Hence Au-Ag complex is a remarkable candidate for tuning the photo adsorption of TiO₂ from UV to visible light. This study presents a novel and tailored method for the fabrication of Au-Ag co-modified TiO₂ particles, and how Au-Ag dependent SPR was applied as the visible light-responsive TiO₂ based photocatalysts in a simple but reliable way. The fabricated Au-Ag co-decorated TiO₂ (Au_xAg(_1-x)/TiO₂) was characterized and proved to own excellent stability and large specific surface area. The optimization of these particles against the wavelength of maximal solar light intensity was confirmed by photo degradation of methylene blue under visible light radiation. This work may provide further insight into the design of TiO₂-based composites with improved photocatalytic properties for environmental remediation and renewable energy utilization.