Electrolysis of acidic sodium chloride solution with a graphite anode. I. Graphite electrode

A graphite anode evolving Cl from a chloride soln. is slowly oxidized to CO and CO2. This oxidn. causes a change in the characteristics of the electrode in aging, comprising a change of the nature of the graphite surface and an increase of the surface area. It appears that a new graphite electrode is covered with a stable oxide that protects it against attack. During continued anodic polarization this stable oxide disappears at a potential of 1.72 v., probably with formation of CO and (or) CO2. The roughness of the surface then increases, attaining a max. value of .apprx.17 times that of a new graphite electrode, which has a roughness factor of 30. The electrochem. active surface areas of a new and of a 2000-hr. aged graphite electrode are 2 and 33 times the geometrical surface area, resp. [on SciFinder (R)]