Thiol treatment tunes interfacial wettability for electrochemical alkynol semi-hydrogenation

Abstract

Electrocatalytic semi-hydrogenation of alkynols holds tremendous advantages over conventional thermocatalysis process. However, the selectivity-activity seesaw effect is a principal obstacle to its further development. Inspired by interfacial self-assembled monolayers, alkanethiols with different alkyl chain lengths are employed to modify the Cu surface for controllably modulating the activity and selectivity in the semi-hydrogenation of alkynols. 1-dodecanethiol-modified Cu nanowires (Cu NWs) exhibit the optimal electrosynthesis of 2-methyl-3-buten-2-ol with excellent specific selectivity (above 93%) in the semi-hydrogenation of 2-methyl-3-butyn-2-ol. Mechanistic studies reveal that the proportion of liquid-like water increases while the proportion of isolated water reduces at the hydrophobic interface. Moreover, we assemble a larger 3 × 100 cm² electrolyzer stack, which can deliver a single-pass alkynol conversion rate of 95% and an excellent alkenol selectivity of 94% at a 15 A stack current. Eventually, the Cu NWs catalyst with thiol treatment is also applicable to the semi-hydrogenation of various unsaturated alkynols.