Chemical stability of sorbitan monolaurate under highly oxidative electrochemical environments

The primary objective of this investigation was to explore the electrochemical oxidation behavior of Sorbitan monolaurate (Span 20) under high-voltage environments. We designed and prepared working electrodes using a mixture containing Span 20 and conductive carbon black as an electron transport material. Linear sweep voltammetry (LSV) served as the technique to monitor the reactions undergone by Span 20. The oxidative products were subjected to analysis using X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance hydrogen spectrum ( 1 H NMR). LSV reveals the decomposition of Span 20 occurring at voltages exceeding 4.2 V, involving two distinct reactions. Further insights from XPS and 1 H NMR demonstrated that Span 20 underwent a two-electron-two-proton electrochemical reaction, producing triketone and 1, 3-diketone with a hydroxyl group positioned at the 2 position. To elucidate these results, a reasoning mechanism was proposed.