Electrodeposition of Elemental Sulfur from Dimethyl Sulfoxide (DMSO)

Elemental sulfur electrodeposition has not been widely studied due to its usage primarily in compound rather than in elemental form, and also due to its high electrical resistivity. Sulfur thin film electrodeposition is reported here from electrolytes containing 0.10 M Na2S4 in dimethyl sulfoxide (DMSO), with either 0.10 M KClO4 or LiClO4 as the supporting electrolyte. The high concentration of sulfur precursor S-4(2-) is obtained by adding Na2S and S to the electrolyte in a molar ratio of 1:3. Anodic electrodeposition of sulfur onto Au electrodes for 48 hr. at a potential of +0.46 V vs. Ag/Ag+ yields a sulfur thin film similar to 10 mu m thick, which appears to be the thickest sulfur film that has ever been electrodeposited. Elemental analysis by energy dispersive X-ray spectroscopy (EDX) suggests that to within themeasurement accuracy, these thin films contain only sulfur. The current density for anodic sulfur electrodeposition is similar to 60% higher in LiClO4-than in KClO4-containing electrolytes, and a more compact sulfur deposit is obtained. Possible applications of anodic sulfur electrodeposition to metal sulfide deposition are briefly discussed. (C) 2018 The Electrochemical Society.