Electrothermal Tandem Catalysis for Acetaldehyde Synthesis From CO 2 and Water

Acetaldehyde (CH 3 CHO) is an important intermediate in various market sectors, while its industrial production mainly relies on fossil fuels‐derived C 2 H 4 and elevated temperature/pressure, leading to massive CO 2 emission. In this study, we proposed a novel electrothermal tandem strategy to efficiently synthesize CH 3 CHO from CO 2 and water under mild conditions, by integrating aqueous CO 2 electrolysis and Fe 3+ ‐promoted Pd 2+ ‐catalyzed Wacker oxidation. Specifically, CO 2 is electrochemically reduced to C 2 H 4 over Ga‐doped Cu/Cu 2 O hybrid and water is oxidized to O 2 over reconstructed Ni 5 P 4 array simultaneously, with respective Faradaic efficiencies of 63.9% and 100%. Then, the generated C 2 H 4 and O 2 react with each other in a separate chemical reactor to produce CH 3 CHO 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 Ga 3+ induces electron transfer to stabilize Cu + species for promoted adsorption and coupling of key *CO intermediates for C 2 H 4 generation, and the Fe 3+ cocatalyst with higher oxidative property relative to traditional Cu 2+ more effectively alleviates Pd 2+ poison caused by CO impurity. This work exhibits tremendous potential for CH 3 CHO synthesis from CO 2 with both economic and environmental benefits.