Arsine Evolution and Water Reduction at an Arsenic Cathode

Abstract

he effects of current density, temperature, acidity, and salt concentration on the evolution of arsine have been studied at arsenic and lead‐arsenic cathodes. Analysis of the data indicates that the surface of the electrode is largely covered with chemisorbed hydrogen at current densities as low as 5–10 ma/cm2, that arsine is formed by reduction of water molecules on the chemisorbed layer of hydrogen, that the rate‐determining step is the disproportionation between adjacent surface hydrides, and that water molecule reduction takes place at the electrode even in 1M sulfuric acid at current densities at least as low as 1 ma/cm2.