Voltammetry of the silver alkylcarboxylate nanoparticles in suspension

Voltammograms of suspensions of silver alkylcarboxylate-stabilized nanoparticles with even numbers of carbon atoms (m=18, 16, 14, 12, 10, and 8) showed the diffusion-controlled anodic peak at ca. 1.2 V versus Ag vertical bar AgxO and the diffusion-controlled cathodic peak of which potential shifted in the positive direction with an increase in m. The nanoparticles consisted of the silver core participating in the anodic peak current and the silver alkylcarboxylate shell participating in the cathodic peak current. On the contrary, molecules of the silver alkylcarboxylates presented the cathodic peak of which potential shifted in the negative direction with an increase in m, in consistent with the m-dependence of the acidity constants of alkylcarboxyl acids. The coating structure of the core with the alkylcarboxylate mimicked silver alkylcarboxylate adsorbed on a planar silver electrode. The cathodic peak potentials for the adsorbed alkylcarboxylate showed the m-dependence similar to the nanoparticles. This behavior was explained by the delocalization of the positive charge over some silver atoms in the core. The nanoparticles were synthesized by heating silver carboxylates at 250 degrees C. (C) 2005 Elsevier Ltd. All rights reserved.