Journal of the Electrochemical Society, Vol.142, No.12, 4103-4107, 1995
Thermoconvection-Enhanced Deposition of Copper
Thermal gradients and thermoconvective flow in the vicinity of the electrode are shown to enhance mass transport of the electroactive species during reduction of copper. The transport-limited current of the copper reduction reaction is more than doubled under conditions of positive and negative thermal gradient in comparison with isothermal conditions. Furthermore, thermal gradients affect strongly the potential dependence of the current. Kinetic and thermodynamic parameters for electrodeposition of copper were determined from polarization curves analyzed with Butler-Volmer, Tafel, and Levich expressions. Under isothermal conditions the exchange current density for the copper reduction reaction was found to be given by log i(0) = 7.95 - 2690T(-1) (i(0) in mA cm(-2) and T in K) under conditions of 10 mM CuSO4 in 2 M H2SO4 io (10 less than or equal to T/degrees C less than or equal to 80). The diffusion coefficient of Cu(II) at 298 K under the same conditions was found to be 5.36 . 10(-6) cm(2) s(-1). Decrease of the effective thickness of the diffusion layer due to thermoconvection in the vicinity of the cathode is responsible for the effect of the gradient on transport-limited current.