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Hematite-Based Solar Water Splitting in Acidic Solutions: Functionalization by Mono- and Multilayers of Iridium
Wei Li1, Stafford W Sheehan2, Da He1
1Department of Chemistry, Merkert Chemistry Center, Boston College, 2609 Beacon St., Chestnut Hill, MA 02467 (USA).
Angewandte Chemie (International Ed. in English)
|July 18, 2015
Summary
Researchers developed a new method for solar water splitting in acidic solutions using an iridium-based water-oxidation catalyst (WOC) on hematite. This breakthrough enables efficient and stable hydrogen production, overcoming previous limitations in acidic environments.
Area of Science:
- Materials Science
- Electrochemistry
- Renewable Energy
Background:
- Solar water splitting in acidic solutions is crucial for hydrogen production but hindered by unstable water-oxidation catalysts (WOCs).
- Iridium-based WOCs offer stability in acids but are prohibitively expensive for widespread use.
- Dual absorber photoelectrochemical cells for acidic conditions remain undemonstrated.
Purpose of the Study:
- To demonstrate solar water splitting in acidic solutions using a dual absorber photoelectrochemical cell.
- To address the challenge of finding stable and cost-effective WOCs for low pH environments.
- To improve the efficiency and stability of hematite-based photoanodes for water oxidation.
Main Methods:
- Application of an ultra-thin monolayer of a molecular iridium WOC to a hematite photoanode.
- Electrochemical characterization to determine the effect of the WOC on the turn-on voltage.
- Testing of a heterogeneous multilayer derivative of the molecular WOC for long-term stability.
Main Results:
- A cathodic shift of 250 mV in turn-on voltage was observed with the molecular Ir WOC monolayer.
- Stable solar water splitting was achieved for over 5 hours using a heterogeneous multilayer derivative.
- Near-unity Faradaic efficiency was maintained during the prolonged water splitting experiments.
Conclusions:
- An ultra-thin molecular iridium WOC on hematite enables solar water splitting in acidic solutions.
- The developed WOC system overcomes the limitations of expensive and unstable catalysts.
- This approach paves the way for efficient and cost-effective hydrogen production from water in acidic media.
