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

Abstract 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/Nv-CN) nanosheets hybrid by in situ deposition of MgAl layered double hydroxide (MgAl LDH) on Nv-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/Nv-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.