Anodic Oxidation of Hypophosphite on a Nickel–Phosphorus Electrode in the Presence of Some Organic Compounds

The effects some sulfur-, nitrogen-, or oxygen-containing organic compounds exert on the hypophosphite oxidation are compared. Catalytic and inhibiting effects of additives, which depend on their nature and occur in different concentration intervals, are discovered and examined. The inhibiting effect, exerted by all substances studied, is accompanied by a shift of steady-state potential in the positive direction and is determined by the adsorbability of substances, which is a function of the nature and number of heteroatoms and substituents. The best inhibiting properties are intrinsic to an additive with an –S–S– fragment and NH₂ groups. Catalytic influence, which is typical only for sulfur-containing compounds at low concentrations, is accompanied by a shift of steady-state potential in the negative direction and may be related to a surface modification and a change in the metal–hydrogen bond energy.