Study on electroreduction of Eu(III) and electrodeposition of Eu–Co in europium toluenesulfonate+DMF

Abstract Europium toluenesulfonate highly soluble in organic solvent was prepared for the first time and was used as the electrolyte in DMF. The composition of its crystalline hydrate was determined as ( p -CH 3 C 6 H 4 SO 3 ) 3 Eu · 7H 2 O. Cyclic voltammetry and the E – t curve resulting from a current step were used to study the electroreduction of Eu(III) in ( p -CH 3 C 6 H 4 SO 3 ) 3 Eu+DMF. The electrode process of Eu(III) reduced on a Pt electrode occurs in two steps: Eu(III)+e − =Eu(II), Eu(II)+2e − =Eu; the first step is quasi-reversible. The diffusion coefficient of Eu(III) was calculated as 5.8×l0 −7 cm 2 s −1 at 25°C. A europium film with a bluish violet lustre and a Eu–Co film with black metallic lustre were obtained by potentiostatic electrolysis. SEM, EDAX and XRD were used to analyze the film. The composition of Eu–Co film is 69.4 at.%Co and 30.6 at.%Eu. It adheres firmly to the copper substrate.