Efficient Hydroxymethanesulfonate Electrosynthesis from CO2 and Sulfite over CuPd1 Single-Atom Alloys

Electrochemical C–S coupling of CO2 and sulfite (SO32–) offers a sustainable alternative for hydroxymethanesulfonate (HMS) synthesis, yet its electrocatalytic selectivity remains far from satisfactory. Here, CuPd1 single-atom alloys (CuPd1-SAA) are developed as a highly efficient catalyst for HMS electrosynthesis, delivering an exceptional Faradaic efficiency of 56.8% and an HMS yield rate of 301.5 mmol h–1 g–1 in an MEA electrolyzer, together with outstanding electrolysis stability for over 200 h of electrolysis. Mechanistic investigations reveal the critical Cu-Pd1 synergy in driving CO2 reduction to *CHOH and C–S coupling of *CHOH with *SO3 for selective HMS generation.