SINGLE-CRYSTAL CU2O FORMATION ON AMORPHOUS-CARBON ELECTRODE AND EFFECT OF ANIONS ON THE CRYSTAL HABIT OF CU2O PARTICLES

Electrodeposition of Cu2+ ion resulted in the growth of Cu2O single-cr ystal particles on an amorphous carbon electrode in solution. Cu2O sin gle crystals grow at potentials higher than -0.55 V vs. saturated calo mel electrode (SCE) in CsClO4 (pH 7) as well as H2SO4 (pH 2.0) and HCl (pH 2.1) solutions. However, Cu2O as well as Cu particles are formed simultaneously at potentials below -0.55 V vs. SCE. The oxygen in the Cu2O may come from water via cuprous hydroxide intermediate. The effec t of anions on the crystal habit of the Cu2O particles was investigate d by changing anions. Hexahedral Cu2O single-crystal particles were pr eferentially formed in CsClO4 solution, but in the presence of sulfate ion the Cu2O particles grow in a polyhedral form. Y-shape particles o f Cu2O were obtained in the presence of chloride ion, which may be due to the effect of stronger adsorption of Cl- on the surface of growing particles. Number density and average size of the particles grown on the electrode vs. the kind of anions and electrodeposition potential a re discussed.