Efficient Hydrogenation of CO ₂ to Higher Alcohols over Cu–Zn–Fe Catalysts: The Role of ZnFe ₂ O ₄ Spinel Precursor

Spinel-structured metal oxides offer unique advantages in heterogeneous catalysis due to their structural stability, tunable electronic properties, and multimetal synergistic effects. Herein, we strategically integrated ZnFe 2 O 4 spinel with a conventional CuFe-based catalyst (CuFeO x ) to enhance the catalytic performance for CO 2 hydrogenation to higher alcohols, achieving a higher alcohol selectivity of 28.9% over the CuZnFeO x catalyst. In the catalyst, ZnFe 2 O 4 stably anchors CuO via strong interfacial adhesion (3.3 J/m 2 ) to form a stable CuO–ZnFe 2 O 4 interface structure that promotes Cu dispersion. And during the subsequent reduction process, this structure modulates the reducibility of Fe 3+ via Cu–ZnFe 2 O 4 synergy, thereby facilitating in situ formation of FeC x sites (FeC x content, 51.6 → 67.7%) in the reaction. Mechanistically, the precisely tuned Cu and FeC x dual-active centers effectively optimize the nondissociative and dissociative activation of CO, promoting C–C coupling for higher alcohol synthesis. Furthermore, oxygen-vacancy-rich ZnO provides additional CO 2 adsorption sites (−1.46 eV) and synergistically stabilizes H 2 /CO species at Cu/Fe active centers. Ultimately, the CO 2 conversion on the CuZnFeO x catalyst increases to 35.2%, and the space–time yield for higher alcohols reaches 125.1 mg·g cat –1 ·h –1, which is 4.4 times higher than that of the CuFeO x catalyst. This study establishes a catalyst design strategy that utilizes ZnFe 2 O 4 spinel integration to regulate the final active structure for the optimized catalytic performance.