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Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment
Published on: April 4, 2017
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Time-dependent measurement of plasmon-induced charge separation on a gold nanoparticle/TiO2 interface by
Tomoki Misaka1, Hiroshi Ohoyama2, Takuya Matsumoto3
1Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, Japan.
Scientific Reports
|October 6, 2022
Summary
This study reveals the slow dynamics of plasmon-induced charge separation (PICS) at gold nanoparticle/TiO2 interfaces. Researchers observed PICS dynamics using electrostatic force microscopy, determining a charge annihilation decay constant of approximately 150 ms.
Area of Science:
- Nanomaterials Science
- Surface Chemistry
- Photocatalysis
Background:
- Localized surface plasmon resonance (LSPR) generates hot carriers for applications like photocatalysis.
- While hot carrier generation/annihilation dynamics are understood, the slow dynamics of plasmon-induced charge separation (PICS) remain unclear.
- Understanding PICS dynamics is crucial for optimizing hot carrier utilization in chemical reactions.
Purpose of the Study:
- To directly observe and quantify the slow dynamics of PICS at a gold nanoparticle (Au NP)/TiO2 interface.
- To investigate the influence of bias voltage on charge accumulation during PICS.
- To determine the charge annihilation rate and model the underlying mechanism.
Main Methods:
- Utilized time-resolved electrostatic force microscopy (EFM) with frequency shift sideband signal analysis.
- Performed measurements on Au NP/TiO2 interfaces under laser irradiation.
- Analyzed the bias voltage dependence of the contact potential difference (CPD) changes induced by PICS.
Main Results:
- Direct observation of slow PICS dynamics at the Au NP/TiO2 interface.
- Demonstrated a bias voltage dependence in the accumulation of holes ([Formula: see text]) in Au NPs, indicating controlled charge separation.
- Determined a charge annihilation decay constant of approximately 150 ms for separated charges at the interface.
Conclusions:
- The slow dynamics of PICS can be directly measured using time-resolved EFM.
- Charge accumulation in plasmonic nanoparticles is influenced by applied bias voltage.
- A simple model based on a transient Schottky barrier effectively describes the observed charge annihilation process, providing insights for photocatalytic applications.
