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 cm 2 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.