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1618330 
Journal Article 
Aqueous solutions of colloidal nickel: radiation-chemical preparation, absorption spectra, and properties 
Ershov, BG 
2000 
1 
Russian Chemical Bulletin
ISSN: 1066-5285
EISSN: 1573-9171 
49 
10 
1715-1721 
WOS:000166102300010 
Radiation-chemical reduction of Ni2+ ions in aqueous
solutions of Ni(ClO4)(2) containing sodium formate or isopropyl alcohol was studied. gamma -
Irradiation of deaerated solutions in the presence of polyethyleneimine, polyacrylate, or
polyvinyl sulfate gives stable metal sols containing spherical particles 2-4 nm in diameter. The
optical absorption spectra of nickel nanoparticles exhibit a band with a maximum at 215+/-5 nm
(epsilon (215) = 4.7.10(3) L mol(-1) cm(-1)) and a shoulder at 350 nm. A mechanism for the
radiation-chemical reduction of Ni2+ ions by hydrated electrons and organic radicals (CO2.-
radical anions in the case of HCOONa and (Me2COH)-O-. radicals in the case of (PrOH)-O-i). The
redox potentials of the Ni2+/Ni-0 and Ni+/Ni-0 pairs (Ni-0 is a nickel atom) are approximately -
2.2 and -1.7 V, respectively. The nanoparticles are readily oxidized by O-2, H2O2 and other
oxidants. The reactions of these species with silver ions yield relatively stable nanoaggregates
containing both nickel and silver in addition to silver nanoparticles. 
gamma-irradiation; aqueous solutions; reduction; nickel; silver; colloids; sols; optical absorption; redox reactions