화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.144, No.9, 3091-3095, 1997
Reduction of Gold in Concentrated LiCl
Reduction of gold from concentrated solutions of LiCl containing low gold concentration was investigated using electrochemical and microscopic techniques. Cyclic voltammetric measurements id solutions containing 0.5 mM Au in 6 M LiCl show two reduction peaks on both platinum and HOPG electrodes, indicating that the reduction of gold occurs in two steps. Chronocoulometric measurements on platinum electrodes give evidence of a two-electron reaction in the region of the first reduction peak, whereas in the region of second peak a three-electron reaction is approached. The morphology of deposited gold on highly oriented pyrolytic graphite (HOPG) substrates from solutions containing 5.10(-4) M AuCl4- in 6 M LiCl was characterized using in situ-scanning tunneling microscopy (STM). In situ STM images in the potential range of the first reduction peak show the formation of gold clusters weakly bound to the HOPG substrate. In the region of the second reduction peak an increase in the z-range of the STM images was observed due to the formation of the three-dimensional gold bulk phase. However no stable gold clusters could be imaged in situ in this potential range due to reproportionation of freshly deposited gold and Au(III) from the electrolyte to form Au(I).