Our group identified the key role of CH3OH/H2O volume ratio on the size and shape control of Pt nanoparticles. The finding was published in CrystEngComm.
Pt truncated octahedra and nanodendrites. (Image by Di Zhou)
The size and shape of Pt nanoparticles largely determine the surface atom arrangements and the electronic properties. Control of particle size and shape heavily relies on the nucleation and growth rates of Pt crystals, which are intimately associated to the synthetic conditions. The researchers reported the synthesis of Pt truncated octahedra and nanodendrites by reducing Pt4+ cations in a methanol/water mixture and using PVP as the capping agent, where the shape mediation of Pt particles was done by simply varying the methanol/water ratio. Structure evolution of the intermediate products during the synthesis was monitored by UV-Vis spectroscopy and TEM/STEM. It was found that methanol-rich solution induced fast reduction of Pt4+ cations and isotropic growth of Pt crystals into truncated octahedra, whereas water-rich solution led to a slow reduction of Pt species and continuous nucleation in the initial stage but a fast autocatalytic growth and oriented attachment during the later stage, forming highly branched nanodendrites.