Visible Light Driven Photoelectrochemical Water Oxidation on Nitrogen-Modified TiO2 Nanowires

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• 作者：Son Hoang ; Siwei Guo ; Nathan T. Hahn ; Allen J. Bard ; C. Buddie Mullins
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：January 11, 2012
• 年：2012
• 卷：12
• 期：1
• 页码：26-32
• 全文大小：372K
• 年卷期：v.12,no.1(January 11, 2012)
• ISSN：1530-6992

文摘

We report hydrothermal synthesis of single crystalline TiO₂ nanowire arrays with unprecedented small feature sizes of 5 nm and lengths up to 4.4 渭m on fluorine-doped tin oxide substrates. A substantial amount of nitrogen (up to 1.08 atomic %) can be incorporated into the TiO₂ lattice via nitridation in NH₃ flow at a relatively low temperature (500 掳C) because of the small cross-section of the nanowires. The low-energy threshold of the incident photon to current efficiency (IPCE) spectra of N-modified TiO₂ samples is at 520 nm, corresponding to 2.4 eV. We also report a simple cobalt treatment for improving the photoelectrochemical (PEC) performance of our N-modified TiO₂ nanowire arrays. With the cobalt treatment, the IPCE of N-modified TiO₂ samples in the ultraviolet region is restored to equal or higher values than those of the unmodified TiO₂ samples, and it remains as high as 18% at 450 nm. We propose that the cobalt treatment enhances PEC performance via two mechanisms: passivating surface states on the N-modified TiO₂ surface and acting as a water oxidation cocatalyst.

Keywords:

Water photo-oxidation; N-modified TiO₂; water oxidation catalyst; hydrothermal synthesis; single crystalline nanowire; photocatalysis