Mechanisms of Electroless Metal Plating II. Formaldehyde Oxidation

A detailed investigation of the decomposition of formaldehyde was carried out to account for the fact that formaldehyde decomposition on Group VIII metals, e.g., palladium, occurs without simultaneous hydrogen generation, while on Group IB metals, e.g., copper, formaldehyde decomposition is accompanied by hydrogen evolution. It was found that, in principle, metals may be divided into three main classes: (i) metals with positive free energy of hydrogen adsorption, (ii) metals with free energy of hydrogen adsorption close to zero, and (iii) metals with negative free energy of hydrogen adsorption. In the case of class (i) metals, formaldehyde oxidation is accompanied by hydrogen evolution. For class (ii) metals, there is no simultaneous hydrogen evolution. Class (iii) metals show low catalytic activity for formaldehyde oxidation. Hence, formaldehyde cannot be used as a reducing agent for electroless plating of class (iii) metals. © 1985, The Electrochemical Society, Inc. All rights reserved.