Activating Effect of Na2S2O3 on the Developing of Galvanic Cell Type Electrophotography

Abstract

The present paper is concerned with a electrophotograph which is developed in NiCl2 solution through the cell reaction of (ZnO|NiCl2|Al). The maximum image density was obtained from the neutral electrolyte solution containing 0.7 mol/l NiCl, 0.7~2.8 mol/l NH4Cl and 0.01 mol/l Na2S2O2. The deposition efficiency of nickel was low in acidic solutions. Nickel was deposited from its ammine complex ion which was stable at pH higher than 6. Thiosulfate ion was effective to accelerate the nickel deposition below the concentration of 10-3 mol/l. A direct electron transfer from Al electrode to Ni2+ seemed to occur rapidly in the solution containing thiosulfate ion above 10-8 mol/l. The potential between the aluminum plate in contact with ZnO layer and a calomel electrode was influenced by the Cl- concentration. Such a result may be ascribed to the increase of the activity of Al8+ ion. The potential mentioned above became stable in the solution with low free Ni2+ concentration. © 1974, The Chemical Society of Japan. All rights reserved.