Simultaneously quantitative and qualitative regulation of active sites of Ni-phyllosilicate for enhanced CO2 hydrogenation to methane.

[Display omitted] • The ultrathin Ni-phyllosilicate was successfully synthesized by ball milling method. • H 2 O 2 played a crucial role of pore-forming reagent to create defects in Ni-phyllosilicate. • Nickel acetylacetonate was the optimal nickel salt precursor to form Ni-phyllosilicate. • Metal utilization rate was significantly improved owing to the ultrathin defect-rich structure. • The optimum catalyst exhibited enhanced low-temperature activity for CO 2 methanation. To address the problems of low metal utilization rate and poor low-temperature activity of the nickel phyllosilicate catalysts for CO 2 methanation, this work prepared ultrathin defect-rich Ni-phyllosilicate through ball milling method in the presence of H 2 O 2 modifier, which simultaneously created active sites with more quantity and higher quality. The instantaneous temperature and high pressure derived from the collision and friction of grinding balls provided driving force for the Ni-phyllosilicate synthesis, and the shear force destroyed the interlayer forces to construct the ultrathin layers. H 2 O 2 molecule could insert the layers and dissociate to O 2 bubbles, whose cavitation effect created holes and defects in the nickel phyllosilicate nanosheets and SiO 2 spheres. H 2 O 2 amount was crucial for the defect construction and the optimum Ni-AA-1H catalyst possessed the ultrathin nanosheet of 0.68 nm and high Ni dispersion of 15.6 %, whose TOF CO2 reached 3.76 × 10−2 s−1 at 160 °C. The in-situ DRIFTS results confirmed the enhanced low-temperature activity and the HCOO− reaction pathway over Ni-AA-1H for CO 2 methanation. Nickel precursor effect was also investigated, and nickel acetylacetonate was determined as the optimal one compared with nickel acetate and nickel chloride, owing to the high steric effect of CH 3 COCHCOCH 3 − group and strong basicity environment during ball milling process. [ABSTRACT FROM AUTHOR]