ヒ素の電着とヒ素電着膜の電気化学的挙動

抄録

Electrodeposition of arsenic has been studied in acidic and alkaline solutions containing As₂O₃. The current efficiency from the electrodeposition of arsenic was approximately 90% in initial 3 hours but it gradually falled down below 50% after 20 hours. The cathode deposits were metallic grey arsenic at low current densities but was less-conductive powdery arsenic at high current densities. An X-ray analysis indicated that the deposits were non-crystalline. Cathodic hydrogen evolution on the electrodeposited arsenic in an acidic solution obeyed the Tafel relation with a slope of 0.12V/decade in a limited range of current densities and the exchange current density for hydrogen was in the order of 10^-3 A m^-2. It was also found that the arsenic electrode was slowly reduced to arsine (AsH₃) during the cathodic polarization experiment. The anodic polarization curves for the arsenic exhibited a Tafel line with a slope of 0.06V/decade.