Interference-Enhanced Plasmonic Photocatalysis via Periodically Ordered Ag Nanodisk Arrays

We report a scalable strategy to fabricate periodically ordered Ag nanodisk arrays on Si nanopillar templates isolated by native SiO₂ (Ag-SiO₂-Si) prepared via a hybrid approach integrating polystyrene (PS) nanosphere lithography and following a metal-assisted chemical etching (MACE) method for enhanced SPR-mediated photocatalysis. Using a 633 nm laser, photocatalytic performance of the Ag nanodisk arrays was evaluated using PATP-to-DMAB reaction as a model system. The catalytic activities on 500 nm period Ag nanodisk array always outperformed those on 800 nm period. This enhancement was attributed to the subwavelength interdisk spacing in the 500 nm period Ag nanodisk array, which facilitated interference of scattered light and thus amplified local electric fields (E-field) intensities in the vicinity of the Ag nanodisks. FDTD simulations confirmed the observed near-field enhancement. Owing to the quadratic dependence of SPR-mediated photocatalytic activity on local E-field intensity, the increased E-field around the 500 nm period Ag nanodisk array accounted for the improved photocatalytic activity. Therefore, our findings highlight periodically ordered array design as a powerful lever for tuning SPR-mediated photocatalysis and offer a pathway toward engineered nanostructures for sensing, energy, and chemical conversion applications.