title: Reversible Redox Cycling of Well-Defined, Ultrasmall Cu/Cu2O Nanoparticles.
abstract: Exceptionally small and well-defined copper (Cu) and cuprite (Cu2O) nanoparticles (NPs) are synthesized by the reaction of mesitylcopper(I) with either H2or air, respectively. In the presence of substoichiometric quantities of ligands, namely, stearic or di(octyl)phosphinic acid (0.1-0.2 equiv vs Cu), ultrasmall nanoparticles are prepared with diameters as low as ∼2 nm, soluble in a range of solvents. The solutions of Cu NPs undergo quantitative oxidation, on exposure to air, to form Cu2O NPs. The Cu2O NPs can be reduced back to Cu(0) NPs using accessible temperatures and low pressures of hydrogen (135 °C, 3 bar H2). This striking reversible redox cycling of the discrete, solubilized Cu/Cu(I) colloids was successfully repeated over 10 cycles, representing 19 separate reactions. The ligands influence the evolution of both composition and size of the nanoparticles, during synthesis and redox cycling, as explored in detail using vacuum-transfer aberration-corrected transmission electron microscopy, X-ray photoelectron spectroscopy, and visible spectroscopy.
authors.affiliation: Department of Chemistry, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: Sebastian D
authors.identifier: 0000-0002-9791-5244
authors.initials: SD
authors.lastname: Pike
authors.affiliation: Department of Chemistry, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: Edward R
authors.initials: ER
authors.lastname: White
authors.affiliation: Department of Materials, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: Anna
authors.identifier: 0000-0002-3747-3763
authors.initials: A
authors.lastname: Regoutz
authors.affiliation: Department of Chemistry, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Sammy
authors.affiliation: Department of Materials, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: David J
authors.initials: DJ
authors.lastname: Payne
authors.affiliation: Department of Chemistry, Oxford University, Chemistry Research Laboratory , 12 Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: Charlotte K
authors.identifier: 0000-0002-0734-1575
authors.initials: CK
authors.lastname: Williams
authors.affiliation: Department of Chemistry, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.|Department of Materials, Imperial College London , Imperial College Road, London SW7 2AZ, U.K.
authors.forename: Milo S P
authors.initials: MS
authors.lastname: Shaffer
keywords: copper nanoparticles; copper(I) oxide nanoparticles; organo-copper(I); redox switching; transmission electron microscopy; ultrasmall nanoparticles