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Published May 1, 2015 | Published + Supplemental Material
Journal Article Open

Unassisted solar-driven photoelectrosynthetic HI splitting using membrane-embedded Si microwire arrays

Abstract

Free-standing, membrane-embedded, Si microwire arrays have been used to affect the solar-driven, unassisted splitting of HI into H_2 and I_3−. The Si microwire arrays were grown by a chemical-vapor-deposition vapor–liquid–solid growth process using Cu growth catalysts, with a radial n+p junction then formed on each microwire. A Nafion proton-exchange membrane was introduced between the microwires and Pt electrocatalysts were then photoelectrochemically deposited on the microwires. The composite Si/Pt–Nafion membrane was mechanically removed from the growth substrate, and Pt electrocatalysts were then also deposited on the back side of the structure. The resulting membrane-bound Si microwire arrays spontaneously split concentrated HI into H_2(g) and I_3− under 1 Sun of simulated solar illumination. The reaction products (i.e. H_2 and I_3−) were confirmed by mass spectrometry and ultraviolet–visible electronic absorption spectroscopy.

Additional Information

© 2015 Royal Society of Chemistry. Received 22 Jan 2015, Accepted 01 Apr 2015, First published online 01 Apr 2015. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. The authors would like to thank Dan Turner–Evans, Morgan Putnam, and Mike Kelzenberg for their generous assistance and donation of Si microwire array samples for some of the preliminary studies; Jacob Good for his assistance with the mass spectrometer; Rick P. Gerhart from the Caltech Glassblowing Shop for fabricating custom borosilicate electrochemical cells; Steve Olson and Mike Roy from the Caltech Machine Shop for fabricating custom free-standing device holders and a sample holder for the absorption spectrometer; and Harry Gray, Harry Atwater, and Bruce Brunschwig for useful discussions and guidance.

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Published - c5ee00227c.pdf

Supplemental Material - c5ee00227c1_si.pdf

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August 20, 2023
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