Electrothermal Tandem Catalysis for Acetaldehyde Synthesis From CO₂ and Water

Acetaldehyde (CH₃CHO) is an important intermediate in various market sectors, while its industrial production mainly relies on fossil fuels-derived C₂H₄ and elevated temperature/pressure, leading to massive CO₂ emission. In this study, we proposed a novel electrothermal tandem strategy to efficiently synthesize CH₃CHO from CO₂ and water under mild conditions, by integrating aqueous CO₂ electrolysis and Fe³⁺-promoted Pd²⁺-catalyzed Wacker oxidation. Specifically, CO₂ is electrochemically reduced to C₂H₄ over Ga-doped Cu/Cu₂O hybrid and water is oxidized to O₂ over reconstructed Ni₅P₄ array simultaneously, with respective Faradaic efficiencies of 63.9% and 100%. Then, the generated C₂H₄ and O₂ react with each other in a separate chemical reactor to produce CH₃CHO with high production rate of 253.9 µmol h^-1 and superior selectivity of 98.3%. Systematic experiments and operando Raman and infrared spectroscopy characterizations verify that the electron-deficient Ga³⁺ induces electron transfer to stabilize Cu⁺ species for promoted adsorption and coupling of key *CO intermediates for C₂H₄ generation, and the Fe³⁺ cocatalyst with higher oxidative property relative to traditional Cu²⁺ more effectively alleviates Pd²⁺ poison caused by CO impurity. This work exhibits tremendous potential for CH₃CHO synthesis from CO₂ with both economic and environmental benefits.