title: Electrochemical solid-state phase transformations of silver nanoparticles.
abstract: Adenosine triphosphate (ATP)-capped silver nanoparticles (ATP-Ag NPs) were synthesized by reduction of AgNO(3) with borohydride in water with ATP as a capping ligand. The NPs obtained were characterized using transmission electron microscopy (TEM), UV-vis absorption spectroscopy, X-ray diffraction, and energy-dispersive X-ray analysis. A typical preparation produced ATP-Ag NPs with diameters of 4.5 ± 1.1 nm containing ~2800 Ag atoms and capped with 250 ATP capping ligands. The negatively charged ATP caps allow NP incorporation into layer-by-layer (LbL) films with poly(diallyldimethylammonium) chloride at thiol-modified Au electrode surfaces. Cyclic voltammetry in a single-layer LbL film of NPs showed a chemically reversible oxidation of Ag NPs to silver halide NPs in aqueous halide solutions and to Ag(2)O NPs in aqueous hydroxide solutions. TEM confirmed that this takes place via a redox-driven solid-state phase transformation. The charge for these nontopotactic phase transformations corresponded to a one-electron redox process per Ag atom in the NP, indicating complete oxidation and reduction of all Ag atoms in each NP during the electrochemical phase transformation.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States.
authors.forename: Poonam
authors.initials: P
authors.lastname: Singh
authors.forename: Kate L
authors.initials: KL
authors.lastname: Parent
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Buttry
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010316:Particle Size; D044367:Phase Transition; D012834:Silver / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D012834:Silver; D000255:Adenosine Triphosphate