Silver Nanoparticle鈭扲eactive Oxygen Species Interactions: Application of a Charging鈭扗ischarging Model

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• 作者：Di He ; Adele M. Jones ; Shikha Garg ; A. Ninh Pham ; T. David Waite
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 7, 2011
• 年：2011
• 卷：115
• 期：13
• 页码：5461-5468
• 全文大小：936K
• 年卷期：v.115,no.13(April 7, 2011)
• ISSN：1932-7455

文摘

The silver-nanoparticle-catalyzed decomposition of hydrogen peroxide (H₂O₂) in pH 9.5 bicarbonate buffer is investigated here with attention given to (i) the mechanism of decomposition, (ii) the role of superoxide in mediating silver nanoparticle re-formation, and (iii) the effect of nanoparticle size on decomposition rate. Silver nanoparticles (AgNPs) of average size between 25.0 and 69.4 nm were synthesized via the reduction of Ag⁺ [the dominant Ag(I) species present] by photochemically produced superoxide at pH 9.5 and characterized by UV鈭抳isible spectroscopy and dynamic light scattering. The ability of these particles to catalytically decompose H₂O₂ was examined by measuring the decay of H₂O₂ and the approach to steady state in AgNP and Ag⁺ concentrations. Additionally, the generation of superoxide on reaction of AgNPs with H₂O₂ was monitored using a chemiluminescence-based method. The second-order rate constants for reaction between AgNPs and H₂O₂ correlated linearly with their average particle size ranging from 35.0 to 3.0 脳 10² M^鈭? s^鈭? for average sizes between 69.4 and 25.0 nm. A sensitive trap-and-trigger chemiluminescence-based method for hydroxyl radical detection showed no evidence for the presence of hydroxyl radicals, though an inhibitory effect of tert-butyl alcohol suggested the presence of a strongly oxidizing species. A process involving the superoxide-mediated charging of silver nanoparticles with subsequent discharge by reaction with oxygen and Ag⁺ leading to regeneration of Ag⁰ and superoxide is proposed to account for the results obtained.