The 85th Meeting of the Israel Chemical Society

The mechanisms of reduction of M(H2O)kn+ to form M°-nano-particles differs from that commonly assumed: The reduction of Ag(H2O)2+ in aqueous solutions by H2 and BH4-

Haya Kornweitz 1 Dan Meyerstein 1,2
1Department of Chemical Sciences, Ariel University, Ariel, Israel
2Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel

The redox potentials of M(H2O)ln+/M°(H2O)k are far too negative for the reduction of M(H2O)ln+ by most common reducing agents. Therefore, the question raised is how do relatively weak reducing agents reduce M(H2O)ln+ to form M°-nanoparticles, M°-NPs? Density functional theory calculations concerning the mechanism of reduction of Ag(H2O)2+ by H2 prove that AgHaq is formed as an intermediate. The AgHaq agglomerize to form a variety of {(AgH)n}aq and {(AgH)nAg}+aq. H2 release occurs only from these agglomerates. It is suggested that the first agglomeration step is {(AgH)n}aq + Ag(H2O)2+ → (Ag2H)+aq. Thus, M°(solvated) are not transients in the formation of M°-NPs except when very strong reducing agents, for example e–aq, are used. Therefore, one has to re-evaluate the results concerning the mechanisms of formation of M°-NPs.









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