Toward Control of Gold Cluster Aggregation on TiO₂ via Surface Treatments

Abstract

Well-definedAu−TiO 2 materials were synthesized by deposition of triphenylphosphine-protected Au 9 clusters on TiO 2 (Aeroxide P-25), pre-treated in eight different ways and subsequently exposed to two post-treatments. X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy studies showed that in most cases the PPh 3 ligand shell was removed upon deposition even before post-treatment, coinciding with some cluster aggregation. However, clusters deposited on TiO 2 treated using H 2 SO 4 and H 2 O 2 showed remarkable resistance to aggregation, even after high-temperature calcination, while clusters on H 2 -treated TiO 2 showed the greatest resistance to aggregation under ozonolysis.

Au101–rGO nanocomposite: immobilization of phosphine-protected gold nanoclusters on reduced graphene oxide without aggregation

“…11 As a result, phosphine-protected gold clusters formulated as Au n (PPh 3 ) m , such as Au 9 (PPh 3 ) 8 (NO 3 ) 3 and Au 101 (PPh 3 ) 21 Cl 5 , have been shown to exhibit catalytic activity in a wide range of reactions, such as hydrogenation of terminal alkynes into alkenes, 12 CO oxidation, 13,14 styrene oxidation to benzaldehyde 15 and styrene epoxide, 16 and benzyl alcohol oxidation. 17,18 However, the size-specific catalytic activity of AuNCs has often been difficult to determine experimentally as clusters are prone to aggregation either during deposition or activation on the support, 19,20 or deactivation of the catalyst following initial reaction. 21 Therefore, methods for the fabrication of gold cluster-based catalysts resilient to aggregation are in high demand in nanomaterials, 22 catalysis 4,16,23,24 and sensing communities.…”

The interaction of size-selected Ru3 clusters with RF-deposited TiO2: probing Ru–CO binding sites with CO-temperature programmed desorption

“…TiO 2 is a photocatalytically active substrate 30 and is a common choice as a substrate for the deposition of clusters. 19,20,[31][32][33][34][35][36][37][38][39][40][41][42][43] Here we used RF-deposited TiO 2 as a substrate. It is a nanoparticulate form of TiO 2 made by radio frequency (RF) sputtering a TiO 2 wafer onto a substrate (sputter deposition) under UHV, in the present case Si (100).…”

Sub-monolayer Au9cluster formationviapulsed nozzle cluster deposition

“…To investigate the usefulness of Pulsed Nozzle Cluster Deposition (PNCD) for chemically synthesised nanoclusters, a representative nanocluster was selected for the study, [Au 9 (PPh 3 ) 8 ] 3+ (hereaer referred to as Au 9 ). Chemically-synthesised, atomically-precise gold clusters were synthesised and puried as reported previously, 21,22 before recrystallisation and the use of nuclear magnetic resonance spectroscopy, mass spectrometry and X-ray crystallography to conrm the size specicity of the clusters. 23 Au 9 was stored at À17 C in the dark before use in the deposition process.…”