Synergistic effects of surface Lewis Base/Acid and nitrogen defect in MgAl layered double Oxides/Carbon nitride heterojunction for efficient photoreduction of carbon dioxide

Highlights: • 2D/2D MgAl LDO/N_v-CN photocatalysts were designed for CO₂RR. • The catalyst exhibits superior photocatalytic CO₂RR activity. • The catalysts achieved the CO evolution rate of 20.47 µmol·g⁻¹·h⁻¹. • The synergistic of defects and Lewis sites promote CO₂ photoreduction activity. Conversion of CO₂ to CO from solar energy on semiconductors is a promising route to renewable energy, but their practicality is limited by the poor adsorption and activation of CO₂ on the semiconductor surface and the low utilization of photovoltaic carriers. Here, we construct a MgAl layered double oxide/nitrogen-deficient carbon nitride (MgAl LDO/N_v-CN) nanosheets hybrid by in situ deposition of MgAl layered double hydroxide (MgAl LDH) on N_v-CN nanosheets followed by subsequent calcination. The MgAl LDO serves as the surface-rich Lewis basic sites to effectively enhance adsorption of CO₂ and H₂O, while the nitrogen defects can enhance the optical absorption of g-C₃N₄ and improve the charge carrier separation. The optimal MgAl LDO/N_v-CN has high photocatalytic activity for CO₂ reduction with a CO generation rate of 20.47 µmol·g⁻¹·h⁻¹ under visible light illumination, which is 6 times higher than that of bulk g-C₃N₄. Our work highlights the significance of synergy of MgAl LDO Lewis base/acid sites and nitrogen vacancy defects in the design of efficient photocatalysts for CO₂ reduction.