Silver-mediated temperature-controlled selective deposition of Pt on hexoctahedral Au nanoparticles and the high performance of Au@AgPt NPs in catalysis and SERS

Abstract

Nanomaterials with high catalytic activity and good SERS properties can be used for sensitive and real-time in situ tracking of a catalytic process via SERS, which can be a powerful tool for investigating the products and mechanisms of the catalytic reaction. In the present work, Au@AgPt NPs with a {431}-faceted hexoctahedral Au core and an AgPt alloy shell exhibiting enhanced catalysis and good SERS activity were prepared by a facile silver-mediated temperature-controlled selective deposition of Pt. The complex hexoctahedral Au nanoparticles were synthesized first as nano-templates, followed by coating with a thin layer of Ag. Then, a temperature-controlled synthesis method for preferably depositing Pt on the hexoctahedral Au NPs was proposed to prepare Au@AgPt NPs. With the increase of the synthesis temperature, the Pt atoms were controlled to selectively deposit on the tips, edges or the entire surface of the nano-templates. By systematically investigating the effects of temperature, precursor consumption and synthesis time on the morphology, composition, optical properties, catalysis and SERS properties of the Au@AgPt NPs, the kinetic and thermodynamic mechanisms of the deposition of Pt on hexoctahedral Au nanoparticles were explored. The performance of the Au@AgPt NPs in SERS-based real-time in situ monitoring of the catalytic reaction was also investigated and verified. Besides, it is easy to regulate and control their SERS and catalytic performances through the selective deposition of Pt, according to the demand of the catalytic reaction and SERS monitoring. This work not only presents a new Au@AgPt nanostructure with good catalytic and SERS properties, but also develops a facile, universal and controllable method for selective deposition of Pt on Au nano-templates with a variety of morphologies.