Controlling Photocatalytic Reactions and Hot Electron Transfer by Rationally Designing Pore Sizes and Encapsulated Plasmonic Nanoparticle Numbers

摘要

Controlled self-assembly of different numbers of gold nanoparticles (AuNPs) in the highly ordered cylindrical anodic aluminum oxide nanopores was achieved by a facile ultrasonication method. The surface plasmon resonance bands became red-shifted by increasing the number of nanoparticles (N), in the top view, from monomer M1 (N = 1) to multimers of M2 (N = 3 +/- 1), M3 (N = 5 +/- 1), and M4 (N = 7 +/- 1). The numerical calculations of the M2 model showed the best match of 2 nm nanogap among 28 nm diameter AuNPs in 53 nm diameter nanopores. When the number of AuNPs inside the nanopores increased, more hotspots were generated, which induced the plasmon-driven photocatalysis on AuNP clusters at the incident visible light of 633 nm. The enhanced photocatalytic reaction of 4-nitrobenzenethiol was observed after sequentially increasing the number of AuNPs, which began at M3 and was maximum for M4. The M3 configuration could be a magical number of AuNP clusters for the nanogap-induced photocatalysis under 633 nm irradiation (similar to 0.2 mW) for 12 min. Our methods should be helpful in adjusting photocatalysis by varying the numbers of nanoparticles inside the tunable nanopores.