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A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles
Published on: April 10, 2019
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Toward Spatial Control of Reaction Selectivity on Photocatalysts Using Area-Selective Atomic Layer Deposition on the
W Wilson McNeary1, William D H Stinson2, Moaz Waqar3
1Catalytic Carbon Transformation and Scale-Up Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
ACS Nano
|December 9, 2024
Summary
Area selective atomic layer deposition (AS-ALD) enhances photocatalytic water splitting by selectively coating TiO2 onto Pt sites. This improves hydrogen production efficiency by suppressing unwanted side reactions.
Area of Science:
- Materials Science
- Electrochemistry
- Nanotechnology
Background:
- Photocatalytic water splitting offers a sustainable route to hydrogen fuel production.
- Current limitations in solar-to-hydrogen efficiency stem from side and back reactions, often due to proximity of reaction sites.
- Existing nanoscopic coatings can block reactants but may hinder overall photocatalyst activity.
Purpose of the Study:
- To enhance reaction selectivity and overall activity in photocatalytic water splitting.
- To utilize area selective atomic layer deposition (AS-ALD) for precise nanoscopic oxide film deposition.
- To investigate the use of TiO2 coatings on metallic cocatalysts (Pt and Au) for improved performance.
Main Methods:
- Area selective atomic layer deposition (AS-ALD) to deposit TiO2 films selectively on Pt cocatalysts, while deactivating Au sites using thiol monolayers.
- Electroanalytical measurements on monometallic thin film electrodes to assess the impact of TiO2 encapsulation on reaction suppression.
- Scanning electrochemical microscopy (SECM) and independent potential control on patterned microelectrodes to evaluate local reaction selectivity.
Main Results:
- TiO2-encapsulated Pt effectively suppressed undesired H2 oxidation and Fe(II)/Fe(III) redox reactions while allowing hydrogen evolution reaction (HER).
- AS-ALD successfully enabled local reaction selectivity on a model photocatalyst platform with patterned Au and Pt microelectrodes.
- Selectively deposited TiO2 coatings reduced back reaction rates by an order of magnitude compared to uncoated samples.
Conclusions:
- AS-ALD is a viable technique for creating semipermeable TiO2 films that enhance selectivity in photocatalytic systems.
- This approach allows for improved efficiency in photocatalytic water splitting by minimizing detrimental side reactions.
- The developed method offers a pathway to more efficient and selective solar fuel production.
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