Fabrication of Gold-Based “Sphere-on-Plate” Hybrid Nanostructures with Dual Plasmonic Absorptions Covering Visible and Near-Infrared II Windows via the Volmer–Weber Growth Mode

We report a synthetic strategy to create gold(Au)-based "sphere-on-plate" hybrid nanostructures (SPHNSs). The surface doping of plate-like Au seeds with Pt/Ag atoms is found to be crucial to increase the lattice spacing, inducing island-like deposition of Au atoms via the Volmer-Weber growth mode. The resulting products are featured with the morphology that quasi-spherical nanoparticles are scattered over the nanoplates. Due to the presence of two distinctly dimensioned particles in one entity, the current Au-based SPHNSs exhibit unique dual plasmonic absorptions, where the visible absorbance centered at 546 nm is related to the size of the anchored particles. Arising from such a plasmonic advantage, the Au-based SPHNSs exhibit enhancement in photothermal conversion under laser irradiations at the wavelengths of both 808 and 1064 nm. The current work offers a feasible route to fabricate noble metal hybrid nanostructures involving zero-dimensional (0D) and two-dimensional (2D) structures, which could work as promising materials for photothermal conversion.