エチレンジアミンおよびEDTA溶液中における銅の錯体形成と電析挙動

抄録

The electrodeposition behavior of copper from Cu (en)₂²⁺, Cu (EDTA)²⁺ and mixture of their complex ions has been investigated. Cathodic current-potential curves were obtained by using a rotating disk electrode and the resistance polarization due to the iR-drop between the electrode and the Luggincapillary was eliminated from the data by the current interrupter method. The slope b of the Tafel relation and the cathodic transfer coefficient α of the discharge reaction of Cu (en)₂²⁺ complex ions were -550mV and 0.145, respectively, at potentials from -750- -1100mV (SCE). Analoguos values for Cu (EDTA)²⁺ complex ions were -250mV and 0.436, respectively, at potentials from -1100- -1250mV (SCE). The exchange current density i_o was determined by extrapolating the Tafel relation to the equilibrium potential, was higher for Cu (en)₂²⁺ than for Cu (EDTA)²⁺.
Further more, for the ligand mixed solution consisting of Cu (EDTA)²⁺ to which etylenediamine had been added, the complexation reaction written
Cu (EDTA)²⁺+nen_??_Cu (en)₂²⁺, Cu (en)₃²⁺, EDTA_free
was controlled by the stability constants of the complex ions (β_EDTA=18.8, β_en=20.0, β_en=19.1). The electrodeposition behavior of copper from mixture of Cu (en)₂²⁺ and Cu (EDTA)²⁺ complex ions is thought to be dependent on electrodeposition of Cu (en)₂²⁺ complex ions.