Electrochemical kinetics of gold dissolving in alkaline thiourea solution

Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The results show that the apparent transfer coefficient of anodic process is 0.0582, diffusion coefficient of thiourea gold complex is 6.04×10~ -6 cm~2/s,anodic reaction order of thiourea is 2.0183, and anodic reaction order of OH~- is 0.0166. The theoretical kinetics equation of gold dissolving in alkaline thiourea solution is deduced, which indicates that anodic reaction order of thiourea is 2, and anodic reaction order of OH~- is 0. The theoretical values of the kinetic parameters are consistent with experimental values very well. The correctness of the mechanism is further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.