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Angew Chem Int Ed Engl. 2015 Mar 2;54(10):2980-5. doi: 10.1002/anie.201411200. Epub 2015 Jan 7.

The nature of photocatalytic "water splitting" on silicon nanowires.

Author information

1
Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, and School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui 230026 (P. R. China) http://staff.ustc.edu.cn/∼yjxiong/

Abstract

Silicon should be an ideal semiconductor material if it can be proven usable for photocatalytic water splitting, given its high natural abundance. Thus it is imperative to explore the possibility of water splitting by running photocatalysis on a silicon surface and to decode the mechanism behind it. It is reported that hydrogen gas can indeed be produced from Si nanowires when illuminated in water, but the reactions are not a real water-splitting process. Instead, the production of hydrogen gas on the Si nanowires occurs through the cleavage of Si-H bonds and the formation of Si-OH bonds, resulting in the low probability of generating oxygen. On the other hand, these two types of surface dangling bonds both extract photoexcited electrons, whose competition greatly impacts on carrier lifetime and reaction efficiency. Thus surface chemistry holds the key to achieving high efficiency in such a photocatalytic system.

KEYWORDS:

charge separation; photocatalysis; semiconductors; silicon; surface chemistry

PMID:
25565663
DOI:
10.1002/anie.201411200

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