Digestive ripening of thiol-capped gold nanoparticles: effects of temperature and electric field

We studied the effects of the temperature of reflux heating and electric field on the digestive ripening of polydisperse gold colloid suspensions with different amounts of dodecanethiol of 0.47, 0.58 and 0.8 g. The reflux heating caused the transition of polydisperse gold colloid suspensions to nearly monodisperse colloid suspensions. The particle size of the nearly monodisperse gold nanoparticles for each gold colloid suspension at corresponding boiling point decreased with increasing the amount of dodecanethiol. No bi-disperse gold colloids were observed after prolonged heating. The electric field of 0.484 V mu m(-1) reduced the time for the gold colloid suspensions of 0.58 g dodecanethiol at electric anode to become nearly monodisperse. The electric field has little effect on the final state of the nearly monodisperse colloid suspensions after prolonged heating.