A selective TiO2-x/Ni catalyst derived from NiTi-layered double hydroxides for efficient photothermal CO2 methanation

Photothermal technology offers distinct advantages for catalytic CO 2 methanation. Herein, we synthesized a series of Ni-based catalysts (denoted as TiO 2-x /Ni-X) through controlled calcination of NiTi-layered double hydroxides (LDHs) precursors at 400–700°C. In a continuous-flow system under xenon lamp irradiation (3.2 W/cm²), the TiO 2-x /Ni-X catalysts exhibited a reduction temperature dependent CH 4 production rate. During 40-hour stability testing, the optimized TiO 2-x /Ni-550 catalyst achieved a sustained CH 4 production rate of 180 mmol g cat −1 h −1 with a remarkable near-unity selectivity (>99 %), and the light irradiation substantially enhanced the CH 4 yield compared to bare thermal catalysis. Comprehensive structural characterization and mechanistic studies revealed competing roles governing catalytic activity, with TiO 2-x /Ni-550 demonstrating an optimal balance for CH 4 generation kinetics.