Electrochemical characterization of platinum black electrodeposited from electrolyte including lead acetate trihydrate

The effect of lead acetate trihydrate on platinum black coating has been examined for the electrolyte free of or including lead acetate trihydrate using cyclic potential–current curves and a multi-pulse current measurement. The current–potential curves measured with a cyclic sweep of a current density in the electrolyte including lead acetate trihydrate show that no peak assigned to the reduction of Pt (IV) to Pt (II) in the process of electrode reactions is observed. The kinetic constant, the exchange current density and the double-layer capacitance, which can be determined from the measured potential–time curves, exhibit significantly different values for H2PtCl6 electrolytes free of or containing lead acetate trihydrate. In particular, the exchange current density for the electrolyte including lead acetate trihydrate is much larger than that for the electrolyte free of lead acetate trihydrate. These experimental results indicate that lead acetate trihydrate significantly enhances the electrode reactions in platinum black coating by mainly lowering a height of the energy barrier for the reduction of Pt (IV) to Pt (0) and by suppressing the reduction of Pt (IV) to Pt (II).