Electrocatalytic C–S Coupling for Efficient Organosulfur Electrosynthesis from Mixed Polyols with >99% of Carbon Selectivity

Electrocatalytic carbon-sulfur (C-S) coupling from polyols offers an efficient route for synthesizing value-added organosulfur compounds under mild conditions. Despite some existing results, their performance, including carbon selectivity and Faradaic efficiency (FE), is far behind what is expected for practical application, especially from biomass-derived mixed polyols. In this work, we present, for the first time, secondary hydroxyl adsorption of polyols on a mesoporous (CuNi)O electrocatalyst that selectively promotes C-C bond oxidation cleavage into a formaldehyde intermediate for C-S coupling to value-added hydroxymethanesulfonate (HMS), without overoxidation to undesirable formate. With glycerol as a model polyol, this route delivers a recordable carbon selectivity of >99% and a superior HMS FE of 59.9% at a high yield rate of 11.8 mmol cm^-2 h^-1 in a flow cell. Meanwhile, this route holds a high economic viability for robust electrosynthesis of high-purity HMS in a large scale, with a total profit of $1450 per ton. More impressively, high performance is also achieved in simulated, biomass-derived mixed polyols, which further bypass costly separation and purification steps for HMS electrosynthesis. The findings provide new design principles to engineer chemisorption properties and optimize product selectivity for electrocatalytic upcycling of mixed feedstocks into high-value-added chemicals.