In Situ Free Radical Growth Mechanism of Platinum Nanoparticles by Microwave Irradiation and Electrocatalytic Properties.

Microwave irradiation was employed for spherical-shaped platinum nanoparticle (Pt NPs) preparation. Spherical Pt NPs indexed with (111) facets were prepared using Pt(II) precursor salt, glycerol as solvent and reducing agent, and polyvinylpyrrolidone (PVP) as a shape directer under microwave irradiation for 3-5 min at 300 °C. Electron spin resonance (ESR) peak at 336.000 mT (milli Tesla) confirmed the free radical formation from aqueous glycerol solution which acted as reducing species under microwave. The 2-8-nm diameter of particles was obtained by high-resolution transmission electron microscope. Dynamic light scattering was used to optimize the microwave dose followed by 33 and 48 nm size and 51 and 67 mV zeta potential of Pt NPs, respectively. The PVP was demonstrated as shape controlling agent investigated by Fourier transmission infrared spectroscopy (FTIR). The electrocatalytic performance of as-prepared Pt colloids was investigated using cyclic voltammetry which showed a higher catalytic activity for ethanol redox reaction.