Oxidation of Ag nanoparticles in aqueous media: Effect of particle size and capping

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• 作者：Yuri L. Mikhlin^a ; ^{yumikh@icct.ru" class="auth_mail} ; ^{yumikh@mail.ru" class="auth_mail} ; Elena A. Vishnyakova^a ; ^b ; Alexander S. Romanchenko^a ; Svetlana V. Saikova^b ; Maxim N. Likhatski^a ; Yurii V. Larichev^c ; Fedor V. Tuzikov^c ; Vladimir I. Zaikovskii^c ; Sergey M. Zharkov^b ; ^d
• 关键词：Silver nanoparticles ; Oxidation ; Resistive switching effect ; X-ray photoelectron spectroscopy
• 刊名：Applied Surface Science
• 出版年：1 April, 2014
• 年：2014
• 卷：297
• 期：Complete
• 页码：75-83
• 全文大小：3240 K

文摘

Many applications and environmental impact of silver-bearing nanomaterials critically depend upon their specific reactivity, which is still poorly understood. Here, silver nanoparticles (Ag NPs) of about 3-5 nm and 10-12 nm in diameter, uncapped and capped with l-glucose or citrate, were prepared, characterized using UV-vis absorption spectroscopy, SAXS, TEM, and their (electro)chemical oxidation was examined in comparison with each other and bulk metal applying scanning tunneling microscopy and spectroscopy, cyclic voltammetry, and XPS. A resistive switching effect was found in the tunneling spectra measured in air at the smaller uncapped Ag NPs deposited on HOPG and was interpreted in terms of Ag transfer between the particle and the probe. The anodic oxidation of these Ag NPs in 1 M NaOH yielded 3D Ag₂O, while only a layer of 鈥減rimary鈥?Ag(I) oxide emerged on larger uncapped nanoparticles during the potential sweep. The formation of AgO at higher potentials proceeded readily at the 鈥減rimary鈥?oxide but was retarded at the smaller NPs. The citrate- and glucose-capping substantially impeded the formation both of Ag₂O and AgO. The findings highlighted, particularly, a non-trivial effect of particle size and transient mobilization of Ag species on the reactions of silver nanoparticles.