Disclosing Support-Size-Dependent Effect on Ambient Light-Driven Photothermal CO₂ Hydrogenation over Nickel/Titanium Dioxide

The size of support in heterogeneous catalysts can strongly affect the catalytic property but is rarely explored in light-driven catalysis. Herein, we demonstrate the size of TiO₂ support governs the selectivity in photothermal CO₂ hydrogenation by tuning the metal-support interactions (MSI). Small-size TiO₂ loading nickel (Ni/TiO₂ -25) with enhanced MSI promotes photo-induced electrons of TiO₂ migrating to Ni nanoparticles, thus favoring the H₂ cleavage and accelerating the CH₄ formation (227.7 mmol g^-1 h^-1 ) under xenon light-induced temperature of 360 °C. Conversely, Ni/TiO₂ -100 with large TiO₂ prefers yielding CO (94.2 mmol g^-1 h^-1 ) due to weak MSI, inefficient charge separation, and inadequate supply of activated hydrogen. Under ambient solar irradiation, Ni/TiO₂ -25 achieves the optimized CH₄ rate (63.0 mmol g^-1 h^-1 ) with selectivity of 99.8 %, while Ni/TiO₂ -100 exhibits the CO selectivity of 90.0 % with rate of 30.0 mmol g^-1 h^-1 . This work offers a novel approach to tailoring light-driven catalytic properties by support size effect.