Modulating Ni−O−V bridges for efficient CO2 hydrogenation to CH4

A strategy is developed to boost CO 2 methanation by regulating the local electron density of active sites over a nickel phyllosilicate catalyst via VO x modification. An optimal NiPs-240-10-Rs-V catalyst, prepared by a solvent-free rapid synthesis method, affords excellent low-temperature performance, achieving a CO 2 conversion of 92.5% and CH 4 selectivity of 99.5% even at 300 °C, ambient pressure. Combined characterization and theoretical studies reveal that the solvent-free rapid synthesis and in-situ doping of V species facilitate the formation of thinner nickel phyllosilicate lamellae (2.14 nm), weaken the metal-support interaction, and enhance the reducibility of Ni(II), ultimately yielding smaller Ni particles (2.30 nm) after reduction and significantly improving the metal utilization efficiency of the catalyst. V species exist as VO x clusters that interact with Ni species through oxygen bridges, forming Ni − O − V bridged active structures. VO x tends to accept electrons, thereby decreasing the local electron density and coordination number of the metallic Ni species. Compared to pristine metallic Ni sites on the V-free catalyst, the Ni − O − V sites help promote the activation of CO 2 and H 2 , significantly lower the formation energy barrier of the key formate (HCOO*) intermediate, and facilitate the hydrogenation of intermediates such as CHO*, CH 3 O* to CH 4 . NiPs-240-10-Rs-V also exhibits excellent hydrothermal stability at 600 °C in 100% water vapor and outstanding start–stop cyclic operation stability for 300 h. Furthermore, in contrast to conventional preparation methods, the solvent-free rapid synthesis method offers advantages such as no solvent consumption and a short preparation time.