An Investigation of Some Electrocatalytic Processes Occurring at Low Potentials at a Nickel Electrode in Base

Abstract

It was observed that nickel in base is not a very effective electrocatalyst for the oxidation of organic species, such as methanol and its derivatives, at low potentials. With regard to the oxidation of reactive inorganic species used in electroless nickel plating baths, the behavior of nickel is rather similar to that of gold in that two mediator species appear to be involved. Anionic species such as hypophosphite and the hydroxytrihydroborate anion commence oxidation well below 0 V(RHE), the reaction being mediated by an interfacial cationic Ni(I) hydrous oxide species. Neutral molecules such as hydrazine commence oxidation just above 0 V, the reaction being mediated by an interfacial Ni(II) hydrous oxide species. Severe deactivation of the surface for a particular reaction occurs when the interfacial species undergoes a chemical change, e.g., when Ni(I) alters to Ni(II) or the hydrous Ni(II) species alters to a less‐hydrated deposit of . As pointed out recently in connection with similar work carried out with cobalt in base, the present approach provides a logical basis for understanding the behavior of reductants used in electroless plating baths.