Effects of alkaline cations (M^+= Li^+, Na^+, K^+, Cs^+) on the electrochemical synthesis of polyaniline in nitric acid electrolyte

The effects of alkaline cations （M^＋ = Li^＋, Na^＋, K^＋, Cs^＋）on the electrochemical synthesis of polyaniline were carfled out under cyclovoltammetric conditions using nitrates of Li^＋, Na^＋, K^＋, and Cs^＋ as the supporting electrolytes. The results show that the oxidation potentials of aniline in the electrolytes decrease as the protonation extent of aniline decreases from the fast scan, which is caused by the decrease of the ionic radius of alkaline metal ions at the same concentration of alkaline cations. With the scan number increasing, the deposit charge Q as the characteristic growth function also depends on the protonation of aniline, and it increases with the ionic radius of alkaline cations increasing. SEM images show the effect of alkaline cations on the morphology of polyaniline. It is clear that the ionic mobility of alkaline cations is further lower than that of W. Alkaline cations and counter-ions were the species responsible for the enhancement of Pani electrosynthesis. Therefore, this is exactly what SEM images show： a relatively rough fibrous structure in the case of Pani-H^＋ suggesting a sponge-like structure and a highly orderly fiber-like structure in the case of Pani-M^＋.

Into the “secret” double layer: Alkali cation mediates the hydrogen evolution reaction in basic medium

The hydrogen evolution reaction(HER) – as an essential half reaction in water electrolysis and chlor-alkali process has been well studied in acidic electrolyte, but much less has been known in basic medium. In this study, by combining kinetic modeling and electrochemical measurements, we show that hydrated alkali cation clusters can adsorb on the surface of HER catalyst in basic electrolyte. The bound H2 O molecules in the "clusters" can thus be in-situ activated through the hydration effect, which dissociate on the catalyst surface as the reactant of HER. The effective concentration and hydration energy of alkali cation can influence the H2 O dissociation rate, and hence the kinetics of HER. Our work demonstrates a new understanding of the HER mechanism in basic reaction electrolyte.