Reduction and aggregation of silver ions at the surface of colloidal silica

Journal Article · Thu Sep 22 04:00:00 UTC 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100089a042· OSTI ID:6768251

Lawless, D; Kapoor, S; Meisel, D ^[1]; Kennepohl, P ^[2]; Serpone, N ^[3]

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1. Argonne National Lab., IL (United States)
2. Argonne National Lab., IL (United States) Concordia Univ., Montreal (Canada)
3. Concordia Univ., Montreal (Canada)

The reduction of silver ions at the surface of 40 [angstrom] colloidal silica particles at pH 9 has been studied using the pulse radiolysis technique. The rate of reaction of e[sub eq][sup [minus]] with Ag[sup +] increases linearly with an increase in the Ag[sup +]/SiO[sub 2] ratio until a ratio of 12:1 is reached. At this loading the reaction becomes independent of the silver concentration at the particle surface. Ag[sup 0] and Ag[sub 2][sup +], the first products of silver ion reduction in aqueous solution, have been identified by their absorption spectra as the primary species formed by the reduction of silver ions at the surface of SiO[sub 2]. Within the time window of the experiments ([<=] [mu]s) there is no evidence of larger silver cluster formations (e.g., Ag[sub 4][sup 2+]) that are formed under identical conditions in the absence of silica. Evidently, the silica surface stabilizes the Ag[sub 2][sup +] cation. Irradiation of Ag[sup +]/SiO[sub 2] solutions with trains of electron pulses leads to the formation of two small silver clusters exhibiting spectral bands at 290 and 330 nm and the conventional colloidal particle with its band at approximately 400 nm. 23 refs., 7 figs.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6768251
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:38; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400102 -- Chemical &amp; Spectral Procedures
400201* -- Chemical &amp; Physicochemical Properties
400600 -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ADSORPTION
AGGLOMERATION
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
COLLOIDS
DECOMPOSITION
DISPERSIONS
IONS
KINETICS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADIATION EFFECTS
RADIOLYSIS
REACTION KINETICS
REDUCTION
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SILVER IONS
SOLID CLUSTERS
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES