Nickel@Siloxene catalytic nanosheets for high-performance CO₂ methanation

Two-dimensional (2D) materials are of considerable interest for catalyzing the heterogeneous conversion of CO₂ to synthetic fuels. In this regard, 2D siloxene nanosheets, have escaped thorough exploration, despite being composed of earth-abundant elements. Herein we demonstrate the remarkable catalytic activity, selectivity, and stability of a nickel@siloxene nanocomposite; it is found that this promising catalytic performance is highly sensitive to the location of the nickel component, being on either the interior or the exterior of adjacent siloxene nanosheets. Control over the location of nickel is achieved by employing the terminal groups of siloxene and varying the solvent used during its nucleation and growth, which ultimately determines the distinct reaction intermediates and pathways for the catalytic CO₂ methanation. Significantly, a CO₂ methanation rate of 100 mmol g_Ni^-1 h^-1 is achieved with over 90% selectivity when nickel resides specifically between the sheets of siloxene.