Synergistic Catalysis over Pd–Fe–Zn with Triple-Interface Structures for Selective CO ₂ Hydrogenation to Ethanol

The hydrogenation of CO 2 to ethanol is considered a promising route for recycling carbon resources while mitigating global warming. Nevertheless, the key scientific challenge lies in the efficient coordination of CO 2 adsorption/activation, intermediate CO stabilization/dissociation, and selective C–C coupling within multistep cascade catalytic processes. Herein, we present a PdFe/NaZnO x catalyst with spatially coupled active centers to enhance cascade catalysis. Systematic characterization and DFT calculations reveal that the catalyst features a dynamic triple-interface structure driven by synergistic interactions among Pd, Fe 3 O 4, and ZnO. This unique configuration achieves efficient CO 2 hydrogenation to ethanol with a space-time yield of 87.5 mg·g cat –1 ·h –1 . Mechanistic insights demonstrate that Na-modified ZnO contributes the primary CO 2 adsorption sites (0.125 mmol/g), while Pd synergizes with Fe 3 O 4 to stabilize H 2 and intermediate CO, exhibiting a 4.1-fold enhancement in nondissociative CO activation compared to Fe/NaZnO x . Crucially, Pd facilitates in situ carburization of Fe 3 O 4 to Fe 5 C 2 (from 46.7 to 74.3%), forming Pd–Fe 5 C 2 interfaces that drive *CO-*CH x coupling. The triple-interface structure enables the efficient transfer of *H/*CO intermediates, achieving 20.2% ethanol selectivity, which is 3.8 times higher than that of conventional Fe/NaZnO x . This work highlights the critical role of interfacial and metal–metal oxide synergy in optimizing C1 intermediate stabilization and cascade catalysis, providing a design strategy for multifunctional composite catalytic systems targeting hydrogenation of CO 2 to ethanol.