EFFECT OF OVERPOTENTIAL ON ELECTROLYTIC HYDROGEN-DEUTERIUM SEPARATION FACTOR ON BRIGHT PLATINUM ELECTRODES IN 1.2N HCL-10 PERCENT D2O

The electrolytic hydrogen-deuterium separation factor, SD, was studied on bright platinum as a function of overpotential in 1.2N HCl-10% D2O at 25° C. SD increased from 4.1 ± 0.21 at −50 mv to 6.5 ± 0.35 at −400 mv, and remained virtually constant between −400 mv and —1.2v applied overpotential. Results agree with published work with H2SO4 but not HCl as electrolyte. Only because there is a plateau in the SD vs. overpotential curve are the ohmic potential drop corrections of little significance. The high degree of reproducibility in results achieved, namely ±5%, is believed to be due to (a) effective exclusion of Cl2 (anode gas) from the cathode compartment, (b) relatively short (1-60 min) electrolyses, and (c) removal of the large pre-electrolysis cathode from the cell prior to an electrolysis. A leaching-distillation process was also employed as the pretreatment, and is shown to be as effective as pre-electrolysis. Tafel plots obtained before and after electrolysis showed no hysteresis, and are in agreement with recent work on copper cathodes, where cathodic saturation currents are observed. © 1969, The Electrochemical Society, Inc. All rights reserved.