Size-Dependent Surface Charging of Nanoparticles

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• 作者：Zareen Abbas ; Christophe Labbez ; Sture Nordholm ; Elisabet Ahlberg
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：April 17, 2008
• 年：2008
• 卷：112
• 期：15
• 页码：5715 - 5723
• 全文大小：195K
• 年卷期：v.112,no.15(April 17, 2008)
• ISSN：1932-7455

文摘

Experimental interest in the possible curvature dependence of particle charging in electrolyte solutions issubjected to theoretical analysis. The corrected Debye-Hückel theory of surface complexation (CDH-SC)and Monte Carlo (MC) simulation are applied to investigate the dependence of surface charging of metaloxide nanoparticles on their size. Surface charge density versus pH curves for spherical metal oxidenanoparticles in the size range of 1-100 nm are calculated at various concentrations of a background electrolyte.The surface charge density of a nanoparticle is found to be highly size-dependent. As the particle diameterdrops to below 10 nm there is considerable increase in the surface charge density as compared with thelimiting values seen for particles larger than 20 nm. This increase in the surface charge density is due to theenhanced screening efficiency of the electrolyte solution around small nanoparticles, which is most prominentfor particles of diameters less than 5 nm. For example, the surface charge densities calculated for 2 nmparticles at 0.1 M concentration are very close to the values obtained for 100 nm particles at 1 M concentration.These predictions of the dependence of surface charge density on particle size by the CDH-SC theory are invery good agreement with the corresponding results obtained by the MC simulations. A shift in the pH valueof the point of zero charge toward higher pH values is also seen with a decreasing particle size.