Facile Synthesis of Monodisperse Pt and Pd Nanoparticles Using Antioxidants

Abstract

Monodispersed Pt and Pd nanoparticles (NPs) were synthesized using the antioxidant gallic acid as a reducing and capping agent. The effects of the reaction time and gallic acid concentration on reduction of metal ions were studied and it was found that these were critical factors affecting the size, shape and productivity of Pt and Pd NPs. Transmission electron microscopy (TEM) analysis showed the presence of spherical NPs of 1 to 30 nm at different reaction times. It was observed that the size of Pt and Pd NPs increased with respect to reaction time. The Pt and Pd NPs with average size of 21 nm were well dispersed after the reaction completed. X-ray diffraction (XRD) and selective area electron diffraction (SAED) revealed the formation of crystalline Pt and Pd NPs. The diffraction peaks at 39 degrees, 45 degrees, 66 degrees and 80 degrees, corresponding to the (111), (200), (220) and (311) lattice planes, respectively, were observed in the Pt and Pd NPs. Inductively coupled plasma (ICP) analysis for residual concentrations of Pt and Pd ions showed that 100% conversion was achieved within 72 h of reaction. Hence, the use of antioxidant as a reducing and capping agent could be an alternative to the conventional synthesis method. This environmentally-benign, simple and cost effective method of synthesizing Pt and Pd NPs may be a novel electrode material for use in fuel cell.