Synthesis of shape-controlled palladium nanoparticles and their platinum-coated counterparts - the importance of the exposed facets and surfactant removal on the electrochemical characteristics

Shape-controlled Pd nanoparticles are synthesized using Cl- ions and the role of oxygen on the shape-control is established. The weakly adsorbing and strongly etching property of Cl- ions is exploited for the first time to synthesize different shapes (nanocubes, truncated octahedra, rods and MTPs) of Pd nanoparticles by varying its concentration. Tert-butyalmine (TBA) and NaBH4 treatments are developed for the removal of adsorbed impurities from the shape-controlled Pd nanoparticles. The surface-hydride of Pd is used to remove the adsorbed impurities and consequently to reduce Pt on Pd surface. The clean electrochemical features of the NaBH4 treated shape-controlled Pd nanoparticles confirms the removal of surface impurities, and the presence of Pt features with the various Pt-coated shape-controlled Pd nanoparticles indicate that Pt is successfully coated on the Pd surface. The shape of Pt-coated Pd nanoparticles and the presence of Pt on the Pd-surface are confirmed through various physical and electrochemical characterizations.Thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of the Indian Institute of Technology Bombay, India and Monash University, Australia