From 2D to 3D Plasmonic Periodic Heterostructures: How Plasmon Resonance Influences on Photocatalytic Degradation

Abstract

Engineering strategies to enhance plasmonic effects in photocatalysis usually focus on nanostructure design. However, the systematic relationship between surface plasmon resonance (SPR) characteristics and catalytic activity, particularly with respect to ordered structures, remains underexplored. This study focus on three types of Au(Ag)-TiO2-based heterogeneous periodic structures-films, nanoholes, and nanocones-spanning from 2D to 3D systems, aiming at systematically elucidating how the plasmon resonance mode and intensity affects photocatalytic degradation. The results show that Ag-TiO2 nanocones exhibit the strongest photocatalytic performance for MB molecules, whereas Au-TiO2 nanocones are more effective for CV molecules. Our understanding of plasmonic resonance has been further deepened by discussing it in the context of two key mechanisms: plasmonic resonance energy transfer (PRET) and hot-electron transfer (HET). As the plasmonic resonance intensity diminishes with morphological adjustments, photocatalytic performance decreases accordingly. Enhancement differences between metals and molecules originate from tuning the diverseoverlap between the designed plasmonic resonance band and the absorption band of dye molecules. Femtosecond transient absorption spectroscopy (fs-TA) reveals that, within materials of different morphologies but the same metal, strong plasmonic effects extend the hot electron lifetime through electron-phonon (e-p) scattering, effectively suppressing charge separation recombination and minimizing non-reactive energy loss through phonon-phonon (p-p) scattering. This efficiently facilitates carrier generation, accelerates energy transfer, and enhances the yield of reactive oxygen species. Therefore, this study provides theoretical guidance for the design of ordered structural models influenced by hot carrier dynamics, enabling the development of efficient photocatalytic systems.