Au LSPR Effect Enhanced R-CeO₂/G-C₃N₄ S-scheme Heterojunction for Accelerating CO₂ Photoreduction Performance

Excellent CO₂ adsorption ability and fast photogenerated carriers' supply are vital conditions for efficient CO₂ photoreduction. In this paper, Au localized surface plasmon resonance (LSPR) has been successfully applied in a R-CeO₂/g-C₃N₄ S-scheme heterojunction photocatalyst for CO₂ photoreduction. R-CeO₂/Au/g-C₃N₄ (CAC-2) exhibited excellent CO₂ photoreduction performance and great stability. The CO yield over CAC-2 is about 50.58 µmol·g^-1·h^-1 under UV-vis light irradiation, which is about 6.7 and 6.0 times higher than that of R-CeO₂ and g-C₃N₄, respectively. FDTD simulation, DFT calculation and photoelectrochemical tests together prove the introduction of Au NPs not only enhances the photogenerated carriers' separation efficiency, but also decreases the formation energy barrier of the important intermediate *COOH, which is beneficial for the CO₂ photoreduction to CO. N₂/CO₂ adsorption-desorption curves indicated that the CAC-2 ternary composite had the largest specific surface area and the best CO₂ adsorption capacity. Meanwhile, DFT calculation confirmed that the reduction sites of the CAC-2 had the highest electron density, which can synergistically enhance the CO₂ photoreduction activity. The improvement of photocatalytic performance can be attributed to the synergistic enhancement of Au LSPR effect and S-scheme heterojunction at the interface. Based on the in situ FTIR, in situ ESR, and ¹³C isotope tracer experiment, a potential LSPR effect-enhanced S-scheme heterojunction catalytic mechanism has been provided, which may represent a significant advancement in the field.