Ni-Ru bimetallic catalysts supported on Ti3C2 MXene-derived TiO2 for highly efficient low-temperature photothermal CO2 methanation

Photothermal conversion of CO 2 to methane offers a promising pathway for simultaneous carbon recycling and renewable energy storage. To date, Ni-based catalysts dominate CO 2 methanation. However, their low-temperature activity under photothermal conditions still requires improvement. MTiO 2 derived from Ti 3 C 2 MXene retains its two-dimensional (2D) layered structure and excellent photothermal conversion properties. Herein, we synthesized Ru-Ni@MTiO 2 catalysts through hydrothermal treatment of Ni-impregnated MTiO 2 with controlled Ru loading ( x  = 1, 3 and 5 wt%). The optimal 3Ru-Ni@MTiO 2 catalyst achieved a CH 4 production rate of 86.25 mmol·g −1 ·h −1 at 300 °C, which is 1.3-fold higher than that of the Ru-free Ni@MTiO 2 counterpart. The superior catalytic performance stems from the synergistic electronic effect between Ni and Ru and their dual-site cooperation. Electron transfer from both Ru and MTiO 2 to Ni sites elevates the electron density of metallic Ni, which weakens the H-H bond and accelerates the dissociative adsorption of H 2 . Furthermore, Ru loading not only broadens the light absorption range and promotes photogenerated charge separation, but also increases the density of moderate basic sites, thus boosting CO 2 adsorption and activation. This work provides new insights into the design of bimetallic photothermal catalysts for CO 2 methanation.