title: Understanding photocatalytic metallization of preadsorbed ionic gold on titania, ceria, and zirconia.
abstract: A nonaqueous photodeposition procedure for forming Au nanoparticles on semiconducting supports (TiO(2), CeO(2), and ZrO(2)) was investigated. Intrinsic excitation of the support was sufficient to induce Au(0) nucleation, without the need for an organic hole-scavenging species. Photoreduction rates were higher over TiO(2) and ZrO(2) than over CeO(2), likely due to a lower rate of photogenerated electron recombination. Illumination resulted in metallization of the adsorbed Au species and formation of crystalline Au nanoparticles dispersed across the oxide surfaces. On the basis of transmission electron microscopy (TEM) evidence of a strong Au particle-metal oxide interaction, it is proposed that Au deposit formation proceeds via the nucleation of highly dispersed clusters which can diffuse and amalgamate at room temperature to form larger surface-defect-immobilized clusters, with the final particle size being significantly smaller than that achieved by conventional aqueous photodeposition. From this work, it is possible to draw several new fundamental insights, with regards to both the nonaqueous photodeposition process and the general mechanism by which dispersed metallic Au nanoparticles are formed from ionic precursors adsorbed upon metal oxide supports.
authors.affiliation: ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Sciences and Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Kydd
authors.forename: Jason
authors.initials: J
authors.lastname: Scott
authors.forename: Wey Yang
authors.initials: WY
authors.lastname: Teoh
authors.forename: Ken
authors.initials: K
authors.lastname: Chiang
authors.forename: Rose
authors.initials: R
authors.lastname: Amal
mesh_terms: D000327:Adsorption; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry; D055668:Photochemical Processes; D013057:Spectrum Analysis; D055672:Static Electricity; D014025:Titanium / Q000737:chemistry*; D014835:Volatilization; D015040:Zirconium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D002563:Cerium; C030583:ceric oxide; D006046:Gold; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide