Quasi-reactive metal-support interaction dictates CO2 methanation activity of Ni/anatase catalysts

In supported metal catalysis, conventional strong metal-support interaction (SMSI) often leads to the encapsulation of active metal sites, thereby suppressing catalytic performance, for instance, nickel-based in thermocatalytic CO 2 hydrogenation. Here, we demonstrate that constructing a defective TiO x overlayer on anatase TiO 2 via room-temperature NaBH 4 treatment effectively transforms the classical SMSI state into a quasi-reactive metal-support interaction (quasi-RMSI) in Ni/TiO 2 -based catalysts. This pre-engineered interface, abundant in Ti 3+ and oxygen vacancies, prevents the formation of a dense TiO x encapsulation layer while facilitating electron transfer to Ni nanoparticles and promoting the activation of both CO 2 and H 2 . As a result, the Ni catalyst exhibits a one-order-of-magnitude increase in the CO 2 methanation rate with nearly 100% CH 4 selectivity, a 12-fold enhancement in turnover frequency, and exceptional long-term stability over 200  h. Combined spectroscopic and microscopic analyses reveal that the quasi-RMSI creates a highly active and accessible Ni-TiO x interface, which significantly accelerates CO 2 dissociation and sequential hydrogenation. This work establishes a general defect-engineering strategy for designing high-performance CO 2 methanation catalysts via tailored quasi-RMSI.