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 CO 2 hydrogenation pathways to produce diverse fuels, such as CH 4 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 CO 2 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 CO 2 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/CeO 2 catalyst achieved 98.2% CH 4 selectivity and a 74.8% CO 2 conversion, with methanation (P2G) as the dominant reaction pathway. At 300 °C, the NiCu/CeO 2 catalyst exhibited 92.3% CO selectivity and a 45.6% CO 2 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/CeO 2 catalysts, Mg facilitates electron transfer to CeO 2 through electron donor interactions. This maintains electron-rich Ni active sites, preserving the Ni 2p 3/2 binding energy and promoting the formation of CHO* intermediates for deep hydrogenation. In contrast, NiCu/CeO 2 catalysts involve electron transfer from both Ni and Cu to the CeO 2 support, resulting in electron-deficient Ni active sites. This increases the Ni 2p 3/2 binding energy by 0.3 eV, inhibiting CO* adsorption while enhancing CO desorption. In conclusion, this work attains selective control over CO 2 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 CO 2 hydrogenation selectivity, thereby offering a promising strategy for the rational design of catalysts with tailored interface electronic structures.