Electrochemical Behavior Of Sulfur And Polysulfide Ions In Eutectic Solvent Ethaline

Elemental sulfur is safe,abundant,cheap,and non-toxic.It is a widely studied chemical element but it is a more complex system.The study of the electrochemical behavior of sulfur is very meaningful,not only for lithium-sulfur,sodium-sulfur batteries,but also for the synthesis of metal sulfides.In addition,it can also be used for the detection of hydrogen sulfide.At the same time,the electrochemical reduction process of sulfur is complex and the product is abundant.The species of polysulfide ion produced by reduction is closely related to the types of electrodes,solvents,and supporting electrolytes.At present,the electrochemical behaviors of sulfur and polysulfide ions in high-temperature molten salts,organic solvents and ionic liquids have been studied.In this paper,the electrochemical behavior of sulfur and polysulfide ions in eutectic solvents Ethaline was studied.Deep eutectic solvent(DES)is a new type of ionic liquid,which not only has the properties of ionic liquids,but also has excellent solubility and conductivity,a wide electrochemical window,non-toxic,biodegradable and other unique advantages and characteristics,so it has been widely used in the field of electrochemistry.At the same time DES also agree the concept of green technology,green chemistry.This article explores the electrochemical behavior of sulfur and polysulfide ions in deep eutectic solvent Ethaline from the following sections:1.The maximum solubility of sulfur in the Ethaline was studied by UV-vis spectroscopy and cyclic voltammetry.The ultraviolet absorption band and absorbance of sulfur in Ethaline were known,and Molar extinction coefficient of sulfur was calculated in Ethaline.2.The electrochemical reduction of sulfur on Au and Pt electrodes was studied.The two electrochemical methods,cyclic voltammetry and chronopotentiometry,were compared and analyzed.Firstly,the cyclic voltammograms of sulfur reduction at the two electrodes were studied.The changes of the electrochemical reduction of sulfur in Ethaline at different scan rates and temperatures were analyzed and compared.The chronopotential diagram was used to analyze the electrochemical behavior of sulfur reduction.Secondly,the difference in the reaction of sulfur on the surface of Au electrode and Pt electrode was compared,and the better electrode was selected for further study.The electrochemical reduction and oxidation of polysulfide ions on Au electrodes was studied.The cyclic voltammetry and the chronopotentiometry were compared and analyzed.Firstly,the conditions of oxidation and reduction of polysulfide ions were studied and analyzed.Then,the reduction mechanism of sulfur in Ethaline was preliminarily predicated.3.The spectroelectrochemical behavior of sulfur at the Au electrode was studied.Firstly,the peak absorption band of polysulfide ions in Ethaline was studied by UV-vis spectrophotometry.Secondly,the specific changes of sulfur reduction in Ethaline were studied by in situ UV-vis spectrophotometry.The previous prediction was validated.