Analysis of hydrogen and deuterium absorption kinetics in Pd nanofilms

An electrochemical quartz crystal microbalance was used to study the kineti cs of hydrogen or deuterium absorption in a Pd nanofilm. The Pd film in a t hickness of 120 nm was deposited on a quartz crystal. Hydrogen was electrol ytically charged into the film and monitored by the frequency shift from di e microbalance. The kinetics curves of hydrogen or deuterium absorption in the nano-scaled Pd thin film were obtained at reduction potentials ranging from -1.2 to -1.5 V. Based on the Fick's law, the diffusion rates of hydrog en or deuterium in the film were slower than those in bulk Pd by several or ders of magnitude. It is proposed that surface effect was the dominant fact or for hydrogen/deuterium absorption in the nano-scaled Pd film. By modifyi ng the Fick's law with a first order reaction equation, the kinetics could be interpreted by a surface-controlled process. (C) 2000 Elsevier Science S .A. All rights reserved.