Hydrogen entry and absorption in ZrO2 coated iron studied by electrochemical permeation and desorption techniques

One (entry) side of iron membranes was coated with ZrO2 by sol-gel method. Hydrogen permeation through and hydrogen desorption from the uncoated and ZrO2 coated iron membranes were studied using the electrochemical detection of hydrogen. The coated and uncoated membranes were charged with hydrogen cathodically generated from 0.1 M NaOH under constant current. During the initial period, the effect of the ZrO2 coating was insignificant. However, the coating quite efficiently prevented the iron surface become more active to hydrogen entry during a long-lasting charging. After cessation of hydrogen charging, the hydrogen desorption was measured at both sides of the membranes. The analysis of the hydrogen desorption rates enabled the determination of the total amounts of hydrogen and distinction its different forms: the diffusible and reversibly trapped hydrogen.