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Chromophore-Catalyst Assembly for Water Oxidation Prepared by Atomic Layer Deposition
Leila Alibabaei1, Robert J Dillon1, Caroline E Reilly1
1Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
ACS Applied Materials & Interfaces
|October 17, 2017
Summary
This study explores visible-light water splitting using a novel photoanode in a dye-sensitized photoelectrosynthesis cell (DSPEC). The design enhances photocurrent by 2.5-fold with a catalyst, despite limitations from chromophore decomposition.
Area of Science:
- Photoelectrochemistry
- Renewable Energy Conversion
- Materials Science
Background:
- Visible-light-driven water splitting is crucial for sustainable hydrogen production.
- Dye-sensitized photoelectrosynthesis cells (DSPECs) offer a promising platform for solar fuel generation.
- Developing efficient photoanodes is key to improving DSPEC performance.
Purpose of the Study:
- To investigate visible-light-driven water splitting in a DSPEC.
- To design and fabricate a novel photoanode incorporating a phosphonic acid-derivatized donor-π-acceptor (D-π-A) organic chromophore and a water oxidation catalyst.
- To evaluate the performance of the DSPEC and understand the underlying mechanisms.
Main Methods:
- Fabrication of a photoanode using a layering strategy: organic dye anchoring, atomic layer deposition (ALD) of TiO2, and catalyst binding.
- Photoelectrochemical measurements (photocurrent) to assess device performance.
- Transient absorption spectroscopy and Density Functional Theory (DFT) calculations to study electron transfer dynamics.
Main Results:
- Photocurrents were 2.5-fold higher with the catalyst present.
- Electron injection from the photoexcited dye was ultrafast, facilitated by molecular orbital orientation.
- Significant recombination (95% by 1.5 ns) between injected electrons and oxidized dye was observed.
- Chromophore decomposition was identified as a limiting factor for O2 production efficiency.
Conclusions:
- The developed photoanode strategy shows promise for enhancing photocurrent in DSPECs.
- Ultrafast electron injection and rapid recombination dynamics were elucidated.
- Chromophore stability remains a challenge for efficient O2 evolution in these systems.
- The presented approach offers a flexible new strategy for photoanode design in solar water splitting.