An in situ IR-Vis Sum Frequency Generation Spectroscopy study of cyanide adsorption during zinc electrodeposition

In this paper, we demonstrate the feasibility of in situ non-linear IR-Vis Sum Frequency Generation (SFG) Spectroscopy investigations at zinc surfaces in electrochemical ambient. We investigated both zinc electrodeposition onto an extraneous electrode and adsorption on polycrystalline zinc. Electrodeposition studies were carried out onto a polycrystalline gold cathode in contact with a Zn-cyanocomplex solution containing free CN-, while adsorption studies were carried out on a polycrystalline zinc electrode in contact with a free-CN- solution. In both experiments, we monitored the spectroscopic features associated with the internal stretching of the adsorbed cyanide (ca. 2100 cm-1) that we exploited as local Au and Zn site probes. Spectroelectrochemical results were complemented by cyclic voltammetric measurements. This proof-of-principle study is encouraging in the view of more concrete applications regarding additive adsorption at zinc electrodes, aiming at a fundamental understanding of the cycling stability of zinc battery anodes.