Article ID Journal Published Year Pages File Type
9876329 Radiation Physics and Chemistry 2005 13 Pages PDF
Abstract
Reduction of Cu2+ ions with and without I− as a ligand was studied in N2-purged alcoholic solutions by pulse radiolysis. In the absence of iodide ion, the initial rate constant for e−sol reaction with Cu2+ was determined following the decay of solvated electrons in different alcohols; kbimol values are in the range of 0.8-1.1×1010 dm3 mol−1 s−1. In the presence of 10−3 mol dm−3 KI, the respective kbimol remained almost same. Generally, on reduction, Cu(II) ion changes to Cu(I) ion initially and later it produces metallic copper (Cu°), and the stability of these intermediates depends on the conditions of the matrix. In the presence of I−, Copper ions such as Cu(II) or Cu(I) ions get reduced to metallic copper (Cu°) having initial absorption around 740 and below 400 nm. Later, at 100 μs time after the electron pulse, it gets transformed into a nanoparticle with an absorption band at 580 nm. Such formation of copper nanoparticle was observed only in 2-propanolic medium in the presence of iodide ions. During γ-radiolysis of N2-purged 1.5×10−4 CuSO4 solutions in 2-propanol, reddish pink colored copper nanoparticles were formed, which are quite similar to those reported earlier in aqueous solution. But, in the presence of I− (2-propanolic solutions), such phenomenon was not noticed on γ-radiolysis. Interestingly, the formation of copper nanoparticle was observed also in the reactions of copper (II) ions with alcohol radicals formed during γ-radiolysis in N2O-purged system, where e−sol were scavenged by N2O. The nanoparticles generated both in N2 and N2O-purged alcoholic systems, viz. methanol, ethanol and 2-propanol, were found to be oxygen sensitive. The contradictory results from pulse and γ-radiolysis studies in the presence and absence of iodide ions are explained to account for the nanoparticle generation.
Related Topics
Physical Sciences and Engineering Physics and Astronomy Radiation
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