Monodisperse nanoparticles (NPs) of CoFe₂O₄ were synthesized as efficient catalyst precursors for CO₂ hydrogenation to produce high value-added C₂–C₄ olefin products, which are important building blocks for the chemical industry. The resulting Na-promoted CoFe₂O₄ catalysts supported on carbon nanotubes (Na–CoFe₂O₄/CNT) exhibited high CO₂ conversion (∼34%) and light olefin selectivity (∼39%), outperforming other reported Fe-based catalysts under similar reaction conditions. Their performance was superior to that of single-metal NP catalysts (Na–Fe₃O₄/CNT and Na–Co/CNT) and a physically mixed (Na–Fe₃O₄ + Co)/CNT catalyst. The superior performance of the Na–CoFe₂O₄/CNT catalyst can be attributed to the facile formation of a unique bimetallic alloy carbide (Fe_1–xCo_x)₅C₂, which results in higher CO₂ conversion and better selectivity toward light olefins in comparison with conventional χ-Fe₅C₂ active sites derived from Fe-only catalysts and significantly improved heavy hydrocarbon (C₂₊) formation in comparison with the Co₂C sites of Co-only catalysts. The single-source precursor CoFe₂O₄ exclusively forms a single-phase alloy carbide promoted by the Na promoter, whereas the mixed (Na–Fe₃O₄ + Co) precursor forms an isolated Co phase with the alloy carbide phase, promoting undesirable CH₄ formation. An optimal value of x ≤ 0.2 for (Fe_1–xCo_x)₅C₂ was predicted using the cluster expansion method and density functional theory, resulting in a stable bimetallic alloy structure.

中文翻译：

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钴铁氧体纳米颗粒形成用于选择性CO ₂加氢为轻烯烃的催化钴铁合金硬质合金相

合成了CoFe ₂ O _4的单分散纳米颗粒（NPs）作为有效的CO ₂加氢催化剂前体，以生产高附加值的C ₂ -C ₄烯烃产品，这是化学工业的重要组成部分。负载在碳纳米管上的Na促进的CoFe ₂ O ₄催化剂（Na–CoFe ₂ O ₄ / CNT）表现出高的CO ₂转化率（〜34％）和轻烯烃选择性（〜39％），优于其他报道的基于Fe的相似反应条件下的催化剂。它们的性能优于单金属NP催化剂（Na–Fe ₃ O₄ / CNT和Na–Co / CNT）和物理混合（Na–Fe ₃ O ₄ + Co）/ CNT催化剂。Na-CoFe ₂ O ₄ / CNT催化剂的优越性能可归因于独特的双金属合金碳化物（Fe _{1– x} Co _x）₅ C ₂的容易形成，这导致更高的CO ₂转化率和更好的选择性。与常规的χ -铁比较轻烯烃₅ c ^ ₂活性点从仅有Fe的催化剂和改进的显著重质烃（C衍生₂₊）形成的比较与联合₂仅Co催化剂的C位。单源前驱体CoFe ₂ O ₄专门形成由Na促进剂促进的单相合金碳化物，而混合的（Na–Fe ₃ O ₄ + Co）前驱物与合金碳化物相形成孤立的Co相，从而促进了不希望有的CH ₄形成。的最佳值X ≤0.2（FE _{1- X}钴_X）₅ c ^ ₂是使用群集膨胀方法和密度泛函理论，从而得到稳定的双金属合金结构预测。