Silver thin film deposited 3-dimensional gold nanorod arrays for plasmonic catalysis

Plasmonic metal nanoparticles are of great importance in heterogeneous catalysis applications including partial oxidations, dehydrogenations, and hydrocarbon reforming. Although utilization of such nanoparticulate metals seems to be a simple and cheap approach for catalysis, their low surface area, un-controlled aggregation, and limited recovery and recycling abilities prevent their further applications. Herein, to overcome these limitations, vertically aligned, highly ordered, and unidirectional 3-dimensional (3D) gold nanorod (AuNR) arrays were fabricated through an oblique angle vapor deposition method. The plasmonic features and catalytic efficiencies of 3D AuNR arrays were further improved by combining them with a thin layer of silver having varying thicknesses. The catalytic activity of fabricated samples was evaluated by the reduction of 4-nitrophenol to 4-aminophenol with NaBH₄ in the absence and presence of laser illumination with different wavelengths. All the results indicate that the current Ag@AuNR substrates are expected to have a broad impact in a range of fields including plasmonic catalysis, sensing, and many others.