Synthesis and characterization of polyhedral Pt nanoparticles: Their catalytic property, surface attachment, self-aggregation and assembly

Figure shows the TEM and HRTEM images of polyhedral Pt nanoparticles synthesized by modified polyol method with the assistance of AgNO 3. It is seen that the large and porous Pt particles are formed by surface attachments, aggregation, and assembly of as-prepared polyhedral Pt nanoparticles upon the removal of PVP polymer. Scale bars: (a–c) 2 nm; (b) 5 nm; (d–e) 20 nm. [Display omitted] ► Pt nanoparticles under size and polyhedral morphology control are synthesized by polyol method of adding AgNO 3. ► The role of AgNO 3 is important for the nucleation, overgrowth, and formation of the tetrahedral, cubic, and octahedral main morphologies of Pt nanoparticles. ► The surface attachment, random and directed aggregation, and assembly of polyhedral Pt nanoparticles in the formation of large, porous, polyhedral, and irregular Pt particles are explored without any assembly techniques. ► Interestingly, polyhedral Pt nanoparticle-based catalyst shows the high catalytic activity. In this paper, we presented the preparation procedure of Pt nanoparticles with the well-controlled polyhedral morphology and size by a modified polyol method using AgNO 3 in accordance with the reduction of H 2PtCl 6 in EG at high temperature around 160 °C. The methods of UV–vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution (HR) TEM measurements were used to characterize their surface morphology, size, and crystal structure. We have observed that the polyhedral Pt nanoparticles of sharp edges and corners were produced in the preferential homogenous growth as well as the formation of porous and large Pt particles by self-aggregation and assembly originating from as-prepared polyhedral Pt nanoparticles. It is most impressive to find that the arrangement of Pt nanoparticles was observed in their surface attachments, self-aggregation, random and directed surface self-assembly by the bottom-up approach. Their high electrocatalytic activity for methanol oxidation was predicted. The findings and results showed that the polyhedral Pt nanoparticle-based catalysts exhibited the high electrocatalytic activity for their potential applications in developing the efficient Pt-based catalysts for direct methanol fuel cells.