Green Approach to Synthesis of Pt and Bimetallic Au@Pt Nanoparticles Using Carica Papaya Leaf Extract and Their Characterization

This study reports a green approach to synthesis of monometallic platinum nanoparticles (Pt NPs) and bimetallic aurium@platinum nanoparticles (Au@Pt) using aqueous leaf extract of Carica papaya as a reducing and stabilizing agent. The nature and morphology of as-synthesized PtNPs and bimetallic Au@Pt NPs were characterized using UV/vis spectroscopy (UV–vis), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray (EDX). HRTEM images reveal that the as-synthesized PtNPs are in the size range of 3.94–5.48 nm with average particle size of 4.50±0.80. The HRTEM image of as-synthesized Au@Pt shows distinguishable objects of almost same spherical shape but having different contrast with size ranging from 4.17 to 13.23 nm and average particle size of 8.70±2.50 nm. The EDX data of Au@Pt nanoparticles reflects bimetallic nature, and the individual metal of the bimetallic Au@Pt nanoparicles are present almost in the ratio 2:1. The narrow size distribution and small average size (