Nucleation and growth of Au and Au–Pd nanoparticles at the beginning of electrochemical deposition

Gold and gold–palladium nanodeposits were obtained by pulse electrolysis in dimethylformamide with 4×10−3 M HAuCl4 and in dimethyl sulfoxide solution with a mixture of 4×10−3 M HAuCl4 and 4×10−3 M PdCl2, respectively. Isolated gold nanoparticles of about 15 nm in diameter were found by SEM observation after 6 ms of electrochemical deposition. Three pulse and pause periods with duration of 6 ms and 300 ms respectively led to an increase in the particle size approximately two times. In case of gold-palladium deposition, no particles were detected after 10 electrochemical cycles while after 50 cycles 10–35 nm nanoparticles were found. Detailed SEM analysis of electrode surface suggested that at the beginning of electrochemical deposition the growth of gold/nucleation of gold–palladium NPs is a preference for mono-Au/bimetallic Au–Pd system.