Structure of Adsorbed Organometallic Rhodium: Model Single Atom Catalysts

Abstract

We have determined the structure of a complex rhodium carbonyl chloride [Rh(CO)2Cl] molecule adsorbed on the TiO2(110) surface by the normal incidence x-ray standing wave technique. The data show that the technique is applicable to reducible oxide systems and that the dominant adsorbed species is undissociated with Rh binding atop bridging oxygen and to the Cl found close to the fivefold coordinated Ti ions in the surface. A minority geminal dicarbonyl species, where Rh-Cl bond scission has occurred, is found bridging the bridging oxygen ions forming a high-symmetry site.

Applying Dynamic and Synchronous DRIFTS/EXAFS to the Structural Reactive Behaviour of Dilute (≤1 wt%) Supported Rh/Al2O3 Catalysts using Quick and Energy Dispersive EXAFS

“…Similarly the majority Rh(CO) 2 Cl species produced from the reaction of the NO -species with CO is, to all intents, identical to that formed via MOCVD of [Rh(CO) 2 Cl] 2 to Al 2 O 3 [15,16] and indeed to majority geminal dicarbonyl species on the stoichiometric (1 9 1) TiO 2 [110] surface [38] via MOCVD of the same organometallic precursor.…”

Adsorption and reaction of Rh(CO)2(acac) on Al2O3/Ni3Al(111)

“…However, these combined temperature programmed desorption-reflection absorption infrared spectroscopy (TPD/RAIRS) experiments failed to provide precise structural relationships between the rhenium subcarbonyls and the thin film support surface, and cluster formation was not characterized. Supported Rh organometallic precursors have also been studied previously on single crystal TiO 2 (110) surfaces, [16][17][18][19][20][21][22] primarily in the group of Hayden. One of the observations of Hayden's work is that the identity of the rhodium precursor ([Rh(CO) 2 Cl] 2 vs. Rh(acac)(CO) 2 ) led to very different catalytic selectivities of the resultant species in CO hydrogenation reactions, providing clear evidence that the surface chemistry of the organometallic complex plays an important role in determining the reactivity of the formed nanoclusters.…”

X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al2O3

“…The volatile organo-metallic [Rh I (CO) 2 Cl] 2 serves as a useful probe molecule to assess both the Cl K-edge and Rh L 3 -edge XAS from a model system that has previously been well studied in terms of the basic chemistry it displays when supported upon metal oxide surfaces and high area supports such as -Al 2 O 3 (see, for instance, Frederick et al, 1987;Binsted et al, 1989;Evans et al, 1992a,b [ok? ], Evans et al, 2000Hayden et al, 1997Hayden et al, , 1998Newton et al, 2001, 2002[Newton, Burnaby et al, 2002or Newton, Jyoti et al, 2002; Newton et al, 2006;Bennett et al, 2007;Roscioni et al, 2013).…”

“…], Evans et al, 2000Hayden et al, 1997Hayden et al, , 1998Newton et al, 2001, 2002[Newton, Burnaby et al, 2002or Newton, Jyoti et al, 2002; Newton et al, 2006;Bennett et al, 2007;Roscioni et al, 2013).…”