Study of the hydrogen absorption/diffusion in Pd 80 Rh 20 alloy in acidic solution

Abstract Hydrogen absorption/diffusion into Pd 80 Rh 20 alloy (50 μm foil) was studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in 0.1 M H 2 SO 4 at 25 °C in the absence and presence of crystal violet. The double layer capacitance, charge transfer resistance, diffusion coefficient and mass transfer coefficient of hydrogen were determined. The mechanism of hydrogen absorption was discussed. Hydrogen adsorption inhibits the kinetics of hydrogen absorption and, in the presence of crystal violet, it proceeds much faster. At more positive potentials crystal violet is probably desorbed and the kinetics of absorption in the absence and in the presence of crystal violet proceeds with similar rate.