Effects of the DC pulse duty ratio on the characteristics of nanoparticles in gold nanofluids

Gold nanoparticles were synthesized using various unipolar DC pulse duty ratios using solution plasma processing (SPP), and their effects on the size distribution and the shape of gold nanoparticles were investigated. The results demonstrated that the power characteristics used for the synthesis of the gold nanoparticles have a strong effect on the fabrication of Au nanoparticles. Generally spherical shaped nanoparticles were fabricated by SPP and as the unipolar DC pulse power increased from 55−40 % duty ratio to 100−0 % duty ratio, the size as well as size distribution of the fabricated nanoparticles decreased, resulting in an average particle size of approximately 18.1±5.0 nm in diameter at 100−0 % duty ratio. Also, the zeta-potential of the gold nanoparticles synthesized at 100−0 % duty ratio was the highest and was measured at −50.8±1.5 mV, which suggested the dispersion of nanoparticles fabricated at 100−0 % duty ratio was more stable than under other conditions. This confirmed the previously reported results, in that increased electrical energy provided from the solution plasma not only made the nanoparticles even smaller in size, but also facilitated good dispersion stability by charging up the nanoparticles negatively.