Synergistic Catalysis over Pd–Fe–Zn with Triple-Interface Structures for Selective CO <sub>2</sub> Hydrogenation to Ethanol
Yuling Ma, Xin Pu, Yangqin Liu, Peng Zhou, Xin Han, Lei Ye, Xinglong Qin, Haitao Xu, Lingtao Kong, Jiangbing Li, Jian Zhang, Jichang Liu
Abstract
High Resolution Image Download MS PowerPoint Slide 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.