Abstract
Localized surface plasmon resonance (LSPR) plays a significant role in the fields of photocatalysis and solar cells. It can not only broaden the spectral response range of materials, but also improve the separation probability of photo-generated electron-hole pairs through local field enhancement or hot electron injection. In this article, the LSPR effects of Au/TiO2 composite photocatalyst, with different sizes and shapes, have been simulated by the finite difference time domain (FDTD) method. The variation tendency of the resonance-absorption peaks and the intensity of enhanced local enhanced electric field were systematically compared and emphasized. When the location of Au nanosphere is gradually immersed into the TiO2 substrate, the local enhanced electric field of the boundary is gradually enhanced. When Au nanoshperes are covered by TiO2 at 100 nm depths, the local enhanced electric field intensities reach the maximum value. However, when Au nanorods are loaded on the surface of the TiO2 substrate, the intensity of the corresponding enhanced local enhanced electric field is the maximum. Au nanospheres produce two strong absorption peaks in the visible light region, which are induced by the LSPR effect and interband transitions between Au nanoparticles and the TiO2 substrate. For the LSPR resonance-absorption peaks, the corresponding position is red-shifted by about 100 nm, as the location of Au nanospheres are gradually immersed into the TiO2 substrate. On the other hand, the size change of the Au nanorods do not lead to a similar variation of the LSPR resonance-absorption peaks, except to change the length-diameter ratio. Meanwhile, the LSPR effects are obviously interfered with by the interband transitions between the Au nanorods and TiO2 substrate. At the end of this article, three photo-generated carrier separation mechanisms are proposed. Among them, the existence of direct electron transfer between Au nanoparticles and the TiO2 substrate leads to the enhanced local enhanced electric field at the boundaries, which is favorable for the improvement of photocatalytic performance of TiO2. These findings could explain the underlying mechanism of some experimental observations in published experimental works, and helpful to design highly efficient composite photocatalysts that contain noble metal co-catalyst nanoparticles.
Highlights
TiO2 is a kind of fascinating photocatalyst that possesses the ability of splitting water, which was first observed by Fujishima and Honda [1]
We considered four different locations of Au nanoparticle loading on the TiO2 substrate as shown in Figure 1: (a) the Au nanoparticle just contacts the surface of the TiO2 substrate, which is labeled as “Model A”; (b) the Au nanoparticle is half-embedded into the TiO2 substrate, and the center of the Au nanoparticle coincides with the surface of the TiO2 substrate, which is labeled as “Model B”; (c) the Au nanoparticle is completely embedded in the TiO2 substrate, which is labeled as “Model C”; and (d) the Au nanoparticle is embedded in the TiO2 substrate to a depth of 100 nm beneath the surface, which is labeled as “Model D”
The effects of Localized surface plasmon resonance (LSPR) of Au nanoparticle loading onto a TiO2 substrate were simulated by the finite difference time domain (FDTD) method
Summary
TiO2 is a kind of fascinating photocatalyst that possesses the ability of splitting water, which was first observed by Fujishima and Honda [1]. Afterwards, many scientists have made many contributions in photocatalytic technology, such as clarifying the intrinsic mechanism, improving the photocatalytic performance, and exploring novel efficient photocatalysts. In order to make efficient use of solar energy, researchers have performed a large number of studies to improve the photocatalytic performance of TiO2. Catalysts 2018, 8, 236 doping with metals [2,3] or non-metals [4,5] into the TiO2 lattice. This approach can narrow the band gap of TiO2 to absorb visible light. Using a noble metal as a co-catalyst loaded onto the surface of TiO2 is another effective modification strategy to choose [6,7].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
