Size dependence of ultrafast charge dynamics in monodisperse Au nanoparticles supported on TiO2 colloidal spheres

Abstract

Sub-nanosecond charge dynamics in monodisperse Au nanoparticles (NPs) supported on TiO2 colloidal spheres are studied as a function of NP diameter using ultrafast transient absorption spectroscopy. The decay of the transmittance changes observed in the region of the plasmon resonance of the Au NPs following photoexcitation of the TiO2 spheres are well-described by a bi-exponential function consisting of a fast component of 2 ps duration associated with electron-phonon scattering, followed by a slow and relatively weak component associated with phonon-phonon scattering. The decay constant characterising the latter component was found to be dependent on the size of the Au NPs, rising from 49 ± 3 to 128 ± 6 ps as the diameter of the Au NPs increased from 12.2 ± 2.2 nm to 24.5 ± 2.8 nm, respectively.

Plasmonic catalysis with designer nanoparticles

“…This was further shown by ultrafast charge dynamics studies and supported by DFT simulations as later described in Figure 5G. 85 These observations agree with reported photocatalytic systems based on TiO 2 and Au. 86 Therefore, these results show that the control over the charge transfer process in plasmonic-support (Au-TiO 2 ) materials can be employed to control the reaction selectivity in LSPR-driven molecular transformations.…”

Manipulating Electron Transfer in Hybrid ZnO–Au Nanostructures: Size of Gold Matters

“…The high values of K app suggest strong association between the ZnO QDs and Au NPs of different sets. In addition, the salient feature of physical significance is that the apparent association constant for ZnO–Au depends on the size of the particles and increases as the size of the gold particles decreases, further authenticating the strong binding of the ZnO QDs with the smaller metallic particulates …”

“…In addition, the salient feature of physical significance is that the apparent association constant for ZnO−Au depends on the size of the particles and increases as the size of the gold particles decreases, further authenticating the strong binding of the ZnO QDs with the smaller metallic particulates. 47 Quenching may also take place when the ZnO QDs are placed in the vicinity of a metal surface through an additional nonradiative decay channel via resonance energy transfer to metal nanostructures as has been seen in many metal− semiconductor nanocomposites, such as Ag−ZnO, Au−ZnO, Al−ZnO, Mg−ZnO, and Pt−ZnO. 8 Forster resonance energy transfer (FRET) is the process involving the nonradiative transfer of excitation energy from an excited donor to a ground state acceptor placed in close proximity, which follows the radiative emission of a lower energy photon.…”

Plasmon Triggered, Enhanced Light–Matter Interactions in Au–MoS2 Coupled System with Superior Photosensitivity

“…However, under the same experimental condition, the photocarrier lifetimes in Au–MoS 2 nanohybrids are found to be 20 and 180 times longer (τ 1 ∼ 8.1 ± 2.1 ps and τ 2 ∼ 8395.9 ± 622.7 ps) than those in pristine MoS 2 under visible-light irradiation (probe). Here, the faster decay (∼8 ps) component corresponds to the electron–phonon scattering, , whereas the prolonged recovery time (∼8 ns) might be attributed to the interband injection of photoinduced electrons (hot-electrons) from Au-NC to MoS 2 layers. − Therefore, The enhanced (∼1.8 × 10 2 times) lifetime of the slower decay component (τ 2 ) implies the efficient generation of “hot electrons” and their subsequent transfer to the adjacent semiconductor creating long-lived e–h pairs, which provide an immense possibility for a highly responsive photodetector using the plasmonic/2D semiconductor coupled system. The charge transfer mechanism in Au–MoS 2 coupled system along with the heterojunction band alignment is schematically illustrated in Figure e.…”