Effect of the Cu electrode formation conditions and surface nano-scale roughness on formaldehyde anodic oxidation

Abstract

The anodic oxidation of formaldehyde on Cu surfaces deposited by electroplating and electroless plating was investigated by using cyclic voltammetry; Cu surface area (nano-scale roughness factor R n) was determined using underpotential thallium monolayer deposition. R n of Cu coatings obtained by electroless plating from solutions containing copper(II) complexes with EDTA, Quadrol, l(+)-tartrate and dl(∓)-tartrate was 1.2–10-fold higher compared to that of electroplated Cu. The anodic currents of HCHO oxidation depended on solution pH and conditions under which the Cu surface was formed. The currents on Cu electrodes formed by electroless plating were higher by a factor up to 20 compared to electroplated ones. The specific activity of most Cu surfaces was in the same range of values (0.3–1.3 mA cm −2) as that of different planes of Cu single-crystal electrode. The higher specific activity (over 3 mA cm −2) was observed in the case of Cu coatings obtained from dl(∓)-tartrate solutions and can be connected with tartrate and formaldehyde compound formed in the electroless plating solutions. The linear dependence of Cu anodic dissolution peak current density on surface roughness factor was observed.