Fabrication of Transition Metal (Mn, Co, Ni, Cu)-Embedded Faveolate ZnFe2O4 Spinel Structure with Robust CO2 Hydrogenation into Value-added C-2(+) Hydrocarbons

CO2 hydrogenation is the most efficient way to achieve the goal of "Carbon Neutral," and the transition metals (Mn, Co, Ni, Cu)-embedded faveolate ZnFe2O4 were fabricated and then evaluated with a CO2 hydrogenation test. The systematic investigation of the effect of the introduced transition metals on the catalytic performance revealed that the activity was influenced by the surface structure, especially by the surface Fe-C percentages. The introduction of Zn could increase CO2 adsorption, thus promoting the reverse water gas shift (RWGS) reaction, which is considered the first step during CO2 hydrogenation. The surface Fe-C species played a significant role during the Fischer-Tropsch (F-T) synthesis, specific to the carbon chain growth process. Among all catalysts, Co-doped ZnFe2O4 exhibited the highest surface Fe-C percentage; therefore, it exhibited the optimal CO2 conversion, C-2(+) selectivity, C-2-C-4 space-time yield, and olefin/paraffin ratio, which were 42.12 %, 81.26 %, 34.64 %, and 40.25 %, respectively. Furthermore, the introduced Co species can also act as active sites to enhance the activation and dissociation of CO2, as confirmed by theoretical adsorption calculations.