600 nm Irradiation-Induced Efficient Photocatalytic CO₂ Reduction by Ultrathin Layered Double Hydroxide Nanosheets

Currently, developing effective photocatalysts for reducing CO₂ to commercial chemicals and fuels has aroused great interest. However, rates of photocatalytic CO₂ reduction remain too low to arouse interest. Herein, we successfully synthesized four different ultrathin MAl-layered double hydroxide (u-MAl-LDH) photocatalysts (where M = Mg²⁺, Co²⁺, Ni²⁺, and Zn²⁺), each possessing a different number of d electrons in e_g orbitals, to explore the influence of the electrons in e_g orbitals on CO₂ reduction under visible light. The u-CoAl-LDH exhibited the best catalytic activity with [Ru­(bpy)₃]­Cl₂·6H₂O as the photosensitizer, and a very high CO₂ to CO conversion rate of 43.73 mmol g^–1 h^–1 can be found under 600 nm irradiation. Results suggest that manipulating the d-electron configuration in ultrathin LDH photocatalysts through judicious M²⁺ cation selection is an excellent strategy for tuning the photocatalytic performance for CO₂ conversion.