Durability of Colloidally Stabilized Supported Nickel and Nickel Platinum Nanoparticles during Redox-Cycling

Abstract

We report on the oxidation and reduction behavior of colloidally stabilized Ni nanoparticles and Pt@NiPt core–shell nanoparticles with a platinum content of 4%. Thin films of both nanoparticle systems were deposited on yttria-stabilized zirconia substrates by spin-coating. Oxidation–reduction cycles were used to remove oxides and organics and obtain metallic particles. The cycling conditions necessary to clean and reduce Pt@NiPt core–shell nanoparticles were milder than for the Ni nanoparticles, which also needed several cycles to burn off residual organics. During cycling, the Ni nanoparticles lost their initially epitaxial relationship with the substrate and adopted a random orientation, while no epitaxial orientation was observable for the core–shell nanoparticles. Reasons for this are discussed together with the influence of platinum on Ni reduction. The Ni and Pt@NiPt nanoparticles sintered during the process but retained crystalline domain diameters close to the original particle diameters. Our results show that colloidally stabilized nanoparticles can be transferred onto a technologically relevant substrate and be reduced to metallic nanoparticles. The fabrication and final structures are discussed as a feasible route to realize solid oxide fuel cell anodes with tailored nickel particle diameter.

Role of Dioleamide Formation during the Synthesis of Core@Shell@Shell Pt@NiPt@Pt Nanoparticles

“…This strain is alleviated by the incorporation of a small amount of platinum, which causes the nickel lattice to expand. The platinum content also hinders oxidation to nickel oxide or nickel­(II) hydroxide . The heterogeneous nucleation of the nickel monomer was only possible due to the existence of platinum seeds, which act as templates for crystal growth.…”

“…The platinum content also hinders oxidation to nickel oxide or nickel(II) hydroxide. 60 The heterogeneous nucleation of the nickel monomer was only possible due to the existence of platinum seeds, 34 which act as templates for crystal growth. Since our Pt@NiPt CSNs have a NiPt alloy shell, platinum and nickel monomer must react at the same time, and platinum is believed to promote the reduction of Ni 2+ .…”