Effect of crystal violet on the kinetics of H sorption into Pd

Hydrogen insertion into Pd foil and Pd thin deposit on gold electrodes was studied in 0.1 M H2SO4 solution. Two paths are possible for hydrogen insertion: (a) indirect, with hydrogen adsorption at the surface followed by absorption and (b) direct absorption. The studies of hydrogen absorption in Pd foil and thin deposits were carried out using classical transient and steady-state techniques and the electrochemical impedance spectroscopy. Presence of dissolved hydrogen in solution at positive potentials may lead to errors in the determination of the isotherms. The aim of this work is to understand how a poison, the crystal violet, can influence hydrogen insertion. In the presence of crystal violet, hydrogen adsorption is inhibited but absorption becomes more reversible. Analysis of the electrochemical data raises the possibility of the direct absorption mechanism. (c) 2005 Elsevier Ltd. All rights reserved.