Plasmon photocatalytic CO2 reduction reactions over Au particles on various substrates

Surface plasmonic effects have been widely used in photocatalytic reactions like CO2 conversion in the past decades. However, owing to the significant controversy in the physical processes of plasmon photocatalytic reactions and difficulty in realizing CO2 reduction, the influence mechanism of the plasmon effect on the CO2 photoreduction is still under debate. In this study, Au particles deposited on various substrates were employed to acquire insights into the plasmon photocatalytic CO2 reduction, including SiO2, n-Si, p-Si, TiO2-SiO2, TiO2-n-Si, and TiO2-p-Si. It was found that the plasmon resonant enhancement (PRE) effect of Au-SiO2 caused by the Au plasmon was stronger than that of Au-TiO2-SiO2 and Au-n-Si (Au-p-Si) in the visible-light range, while it was weaker for Au-n-Si (Au-p-Si) samples than Au-TiO2-n-Si (Au-TiO2-p-Si). The simulation results agree with the experimental conclusions. The photocatalytic results indicated that the catalytic activity of Au-n-Si (Au-p-Si) samples was lower than that of Au-TiO2-n-Si (Au-TiO2-p-Si), and Au-SiO2 was lower than Au-TiO2-SiO2 and Au-n-Si (Au-p-Si) samples, suggesting that the direct electron transfer (DET) mechanism was dominant here compared with the PRE mechanism.