Controlling CH ₄ /CO Selectivity in CO ₂ Hydrogenation via Electronic Metal–Support Interaction at Ni-CeO ₂ Interfaces of Mg/Cu-Doped Catalysts

The rational design of catalysts is essential for flexibly modulating CO2 hydrogenation pathways to produce diverse fuels, such as CH4 and CO. This approach offers new strategies for advancing sustainable carbon utilization. While metal–support interactions are a key strategy for achieving selective control in CO2 hydrogenation pathways, the precise mechanisms by which interfacial structures influence surface intermediate formation and reaction pathways remain unclear. This study involves the synthesis of a series of cerium oxide-supported bimetallic catalysts, utilizing bimetallic organic frameworks (MOFs) as precursors. The objective is to investigate the optimization mechanisms of metal–support interface regulation for CO2 hydrogenation pathways and to elucidate the crucial role of electron transfer at the metal–support interface. Catalyst performance tests demonstrated that at 200 °C, the NiMg/CeO2 catalyst achieved 98.2% CH4 selectivity and a 74.8% CO2 conversion, with methanation (P2G) as the dominant reaction pathway. At 300 °C, the NiCu/CeO2 catalyst exhibited 92.3% CO selectivity and a 45.6% CO2 conversion, primarily driven by the reverse water–gas shift reaction (RWGS). Both catalysts demonstrated exceptional stability, maintaining over 91% of their initial activity after 136 h of operation. A series of spectroscopic characterizations and density functional theory (DFT) calculations reveal that on NiMg/CeO2 catalysts, Mg facilitates electron transfer to CeO2 through electron donor interactions. This maintains electron-rich Ni active sites, preserving the Ni 2p3/2 binding energy and promoting the formation of CHO* intermediates for deep hydrogenation. In contrast, NiCu/CeO2 catalysts involve electron transfer from both Ni and Cu to the CeO2 support, resulting in electron-deficient Ni active sites. This increases the Ni 2p3/2 binding energy by 0.3 eV, inhibiting CO* adsorption while enhancing CO desorption. In conclusion, this work attains selective control over CO2 hydrogenation through the introduction of a secondary metal, which precisely modulates the electronic state of Ni. It elucidates the mechanism by which electronic metal–support interactions (EMSI) influence CO2 hydrogenation selectivity, thereby offering a promising strategy for the rational design of catalysts with tailored interface electronic structures.