Effect of gelatin on electrodeposition of tellurium from alkaline electrolyte

Abstract

The effect of gelatin as an additive on tellurium (Te) electrodeposition process was studied by linear sweep voltammogram (LSV) and electrochemical impedance spectroscopy (EIS) in alkaline electrolyte (NaOH). It was found that deposition, corrosion and recrystallization occurred almost simultaneously during Te electrodeposition process, resulting in a porous structure of Te products. Gelatin helped to improve the corrosion resistance and limited current density, and reduce the bath potential at the same current density. LSV showed that the physical adsorption of gelatin on the Titanium (Ti) plate affected the electrodeposition process of Te. EIS results indicated that the gelatin had little effect on the electron transfer of Te electrodeposition but disturbed the diffusion of TeO32−. Equivalent circuit and deposition model of Te electrodeposition process with and without gelatin were deduced. Furthermore, high purity Te products were deposited and obtained on Ti plate from electrolyte with different content of gelatin by chronopotentiometry (CP) for 48 h at 80 A∙m−2, which indicated that moderate amount of gelatin could increase both bath potential and current efficiency of Te electrodeposition. Morphological, structural and pure characterizations of Te products were studied by x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), respectively. Introduction of gelatin could not change the morphology of Te products but acted as a grain refiner, that increased the purity of Te products.