Abstract:An interesting and simple strategy to prepare Pt nanoparticle arrays with different morphologies on a substrate was developed by using monolayer colloidal crystal as a template, followed by depositing a layer of Pt film and annealing at different temperatures. Hat-shaped, cup-shaped, rice-shaped and sphere-shaped Pt nanoparticle array were obtained after annealing the PS template with Pt shell at 300℃, 500℃, 700℃ and 900℃, respectively. Their extinction spectra presented two obvious peaks, assigning to transverse and longitudinal localized surface plasmon resonances of the Pt nanoparticles. The transverse and longitudinal localized surface plasmon resonances peaks both blue shifted when geometrical morphology changed from hat-shaped to cup-shaped, and then to rice-shaped due to increasing annealing temperature. The transverse localized surface plasmon resonances peaks blue shifted from 487 nm to 453 nm, and longitudinal localized surface plasmon resonances peaks blue shifted from 1201 nm to 898 nm. With strong absorption in near infrared, the hat-shaped, cup-shaped and rice-shaped Pt nanoparticles array may be suitable for thermotherapy application. However, in the curves of extinction spectra of the hat-shaped, cup-shaped and rice-shaped Pt nanoparticle arrays, the Bragg diffraction peaks were not very obvious. This may be attributed to overlap of their localized surface plasmon resonance peaks and diffraction peaks or absorbance of Pt nanoparticles is too high, resulting in diffraction peak too weak to be detected. Compared with hat-shaped, cup-shaped and rice-shaped Pt nanoparticle array, in the curve of extinction spectra of sphere-shaped Pt nanoparticle array, there was only one localized surface plasmon resonance peak because of its symmetrical nanostructure. But it presented a peak at 635 nm, which is assigned to Bragg diffraction of the highly ordered structure of the Pt nanosphere array. In a word, this controlling annealing temperature strategy is simple and could be potentially extended to prepare novel anisotropic nanostructures for other materials, which is difficult to be synthesized via conventional wet chemical method. And this method would promote more research efforts in developing new methods to fabricate asymmetrical nanostructures. Additionally, these novel properties originating from the anisotropic nanostructures may open up new applications in many fields.