Directly Probing Charge Separation at Interface of TiO2 Phase Junction.
Yuying Gao1,2,3, Jian Zhu1,3, Hongyu An1,2,3
1State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy , Zhongshan Road 457, Dalian 116023, China.
The Journal of Physical Chemistry Letters
|March 15, 2017
Summary
We directly measured the surface potential of TiO2 phase junctions, revealing a built-in electric field that drives efficient electron transfer. This finding enhances understanding of charge separation in photocatalysis.
Area of Science:
- Materials Science
- Surface Science
- Photocatalysis
Background:
- Phase junctions are key for charge separation in photocatalysis and photochemistry.
- Understanding band alignment at phase junction interfaces is crucial for optimizing charge dynamics.
Purpose of the Study:
- To directly measure the surface potential profile across a TiO2 phase junction interface.
- To investigate the impact of the built-in electric field on charge transfer dynamics.
- To explore how tunable anatase nanoparticle sizes influence surface photovoltage and charge separation.
Main Methods:
- Kelvin Probe Force Microscopy (KPFM) for surface potential profiling.
- Home-built spatially resolved surface photovoltage spectroscopy (SRSPS) for charge transfer analysis.
- Fabrication of TiO2 phase junctions with tunable anatase nanoparticle sizes.
Main Results:
- A significant built-in electric field (up to 1 kV/cm) was detected across the rutile-to-anatase TiO2 interface.
- Direct evidence of vectorial charge transfer from rutile to anatase was observed.
- Tunable anatase nanoparticle sizes enhanced surface photovoltage by creating depleted space charge regions, improving charge separation efficiency.
Conclusions:
- The built-in electric field at TiO2 phase junctions plays a critical role in vectorial charge transfer.
- Controlling anatase nanoparticle size is an effective strategy to enhance charge separation efficiency in photocatalysts.
- These findings provide a foundation for designing advanced artificial photocatalysts with improved performance.
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