The Effect of Protonated Ethionine Adsorption on Bi(III) Electroreduction in Chlorate(VII) Solutions with Varied Water Activity

Nicotinamide as a Catalyst for Zn2+ Electroreduction in Acetate Buffer

The paper presents the catalytic influence of nicotinamide on Zn2+ electroreduction. Changes in differential capacitance curves of the double layer Hg/acetate buffer pH = 6.0 as well as changes in zero charge potential values indicate nicotinamide adsorption with the aromatic ring on the electrode surface. This adsorption is responsible for its catalytic influence on the kinetics of Zn2+ ion electroreduction from the acetate buffer solution. The effect is stronger with increasing nicotinamide concentration. It is confirmed by the following factors: the increase in standard electrode rate constants, the reduction in the distance between anode and cathodic peaks on CV voltamperograms, and the decrease in activation resistance associated with the electrode reaction for nicotinamide solutions relative to those obtained in the case of reference solution. A very high catalytic capacity of vitamin B3 on Zn2+ ion electroreduction kinetics from pH = 6.0 acetate buffer can be explained by the formation of an active complex on the surface of the mercury electrode: Zn2+ nicotinamide, which can be described as a bridge facilitating electron exchange.