title: Synthesis of stable ligand-free gold-palladium nanoparticles using a simple excess anion method.
abstract: We report a convenient excess anion modification and post-reduction step to the impregnation method which permits the reproducible preparation of supported bimetallic AuPd nanoparticles having a tight particle size distribution comparable to that found for sol-immobilization materials but without the complication of ligands adsorbed on the particle surface. The advantageous features of the modified impregnation materials compared to those made by conventional impregnation include a smaller average particle size, an optimized random alloy composition, and improved compositional uniformity from particle-to-particle resulting in higher activity and stability compared to the catalysts prepared using both conventional impregnation and sol immobilization methods. Detailed STEM combined with EDX analyses of individual particles have revealed that an increase in anion concentration increases the gold content of individual particles in the resultant catalyst, thus providing a method to control/tune the composition of the nanoalloy particles. The improved activity and stability characteristics of these new catalysts are demonstrated using (i) the direct synthesis of hydrogen peroxide and (ii) the solvent-free aerobic oxidation of benzyl alcohol as case studies.
authors: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.
authors: Meenakshisundaram
authors: M
authors: Sankar
authors: Qian
authors: Q
authors: He
authors: Moataz
authors: M
authors: Morad
authors: James
authors: J
authors: Pritchard
authors: Simon J
authors: SJ
authors: Freakley
authors: Jennifer K
authors: JK
authors: Edwards
authors: Stuart H
authors: SH
authors: Taylor
authors: David J
authors: DJ
authors: Morgan
authors: Albert F
authors: AF
authors: Carley
authors: David W
authors: DW
authors: Knight
authors: Christopher J
authors: CJ
authors: Kiely
authors: Graham J
authors: GJ
authors: Hutchings
mesh_terms: D000838:Anions; D019905:Benzyl Alcohol / Q000737:chemistry*; D002384:Catalysis; D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D000838:Anions; D008024:Ligands; D046911:Macromolecular Substances; D010165:Palladium; D006046:Gold; D019905:Benzyl Alcohol