Kinetic studies of gold(III) chloride complex reduction and solid phase precipitation in acidic aqueous system using dimethylamine borane as reducing agent

Kinetics of gold(III) chloride complex ions reduction with dimethylamine borane and precipitation of gold nanoparticles was investigated. The influence of concentrations of reductant, gold(III) chloride complex ions, neutral salt and chloride ions as well as temperature on the process was reported. Experimental results were used to determine parameters in the Arrhenius equation. A set of reactions occurring in the system was proposed. Rate equations were presented and verified. It was proposed that state of the catalytic surface of gold particles play a crucial role in the mechanism of the reaction and competition between AuCl4− adsorption and AuCl4− reduction on the metal particles exists in the system. Microscopic observations as well as analysis of the particles were also performed.