v: The Role of Ion Migration and Alloy Formation on the Stability of Core Shell Cocatalysts for Photoinduced Water Splitting

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• 作者：NicoleS. Hondow ; Yi-Hsin Chou ; Kasim Sader ; Rik Brydson ; Richard E. Douthwaite
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：December 30, 2010
• 年：2010
• 卷：114
• 期：51
• 页码：22758-22762
• 全文大小：182K
• 年卷期：v.114,no.51(December 30, 2010)
• ISSN：1932-7455

文摘

Semiconductor−metal nanoparticle composites can mediate the photoinduced reaction of water to H₂ and O₂. High spatial resolution microscopic analysis was used to investigate the structure and composition of nominally NiO/Ni core shell nanoparticles supported on the semiconductors NiTa₂O₆ and InTaO₄, respectively. For NiTa₂O₆ the metal nanoparticles were confirmed as NiO/Ni core shell structures and photoreaction demonstrated that H₂ and O₂ were evolved from water at 2.75 and 1.00 μmol g⁻¹ h⁻¹, respectively, under ca. 1 W/cm⁻² using an unfiltered 300W Xe lamp. Analysis of the composite after reaction showed evidence of degradation of the NiO/Ni nanoparticles to Ni(OH)₂. For InTaO₄ bulk modification of the core shell nanoparticles occurred via diffusion of indium ions from the InTaO₄ semiconductor to the nanoparticles to give a new core shell structure best formulated as Ni_1.25In_0.75O₃/Ni₃In. Although all other analytical data (PXRD, DRUVS, BET, SEM) is essentially identical to that reported for NiO/Ni:InTaO₄, the activity of Ni_1.25In_0.75O₃/Ni₃In:InTaO₄ for the photoinduced water splitting reaction was significantly less, exhibiting no activity with wavelengths >400 nm and only H₂ under unfiltered illumination. In contrast to NiO/Ni, degradation of Ni_1.25In_0.75O₃/Ni₃In core shell nanoparticles was not observed. The data indicate that ion diffusion between the semiconductor and nanoparticle are likely to partly explain why obtaining reproducible photoreactions using these complex systems is often difficult to achieve and that ion diffusion can be detrimental to photoactivity.