Unravelling the CO2 methanation mechanisms on a Ni-BaTiO3 catalyst: A theoretical investigation

Solar-induced photothermal catalysis of CO 2 reduction is an effective method for chemical CO 2 conversion with great potential. Understanding its reaction mechanism is crucial for the development of new catalysts. In this work, the mechanism of CO 2 reduction on a BaTiO 3 supported Ni catalyst was studied using density functional theory (DFT). The presence of the BaTiO 3 base was found to have great significance in the adsorption and activation of CO 2 . The dominant reaction pathway of CO 2 reduction on the BaTiO 3 supported Ni catalyst is calculated as CO 2 (g)→CO 2 →CO→COH→HCOH→CH→CH 2 →CH 3 →CH 4 →CH 4 (g) and is rate-limited by the reduction of CO, with a corresponding energy barrier of 0.94 eV, which is nearly 1.00 eV lower than that on the pure Ni surface. The BaTiO 3 base not only induces wrinkling distortion of the Ni surface, which facilitates the step of CO hydrogenation, but also results in an upshift of the d -band centre and Fermi level of the catalyst, which enhances the binding strength of the catalyst with the reaction intermediates. Based on the projected density of states (PDOS) analysis, the BaTiO 3 base strongly promotes the σ-bonding interaction between the Ni surface and CO. The stronger adsorption of CO on the surface of the BaTiO 3 supported Ni catalyst results in the reduction reaction selectively generating CH 4 but not CO. • Lattice mismatch and SMSI with BaTiO 3 results in a wrinkled Ni surface. • The wrinkled surface enhances the σ-bonding with CO. • The introduction of BaTiO 3 leads to the upshift of d-band centre and Fermi level. • CO 2 methanation follows the redox pathway and go through COH intermediate.