On electronic and geometric effects of alloying An infrared spectroscopic investigation of the adsorption of carbon monoxide on platinum-copper alloys

Calorimetric measurement of adsorption and adhesion energies of Cu on Pt(111)

“…The heat of adsorption data in Figure 1 was divided into three distinct regions based on the growth of Cu on Pt(111) described above. In region 1 (0-1 ML, where 1 ML is defined by the density of Pt atoms in the (111) plane, 1.52x10 15 atoms/cm 2 ), Cu adsorbs with an initial heat of adsorption of 357 kJ/mol, the heat of adsorption decreases over the first 1 ML to 339 kJ/mol. Figure 2 shows the heat of adsorption in region 1 in more detail.…”

“…The fraction of metal atoms that transiently adsorb, but do not stick permanently to the surface, are measured using a QMS at the magic angle and compared to a reference zero sticking pulse from a hot Ta flag. The total Cu coverage is recorded in monolayer (ML) Cu coverage, where 1 ML = 1.5x10 15 atoms/cm 2 which is the atomic density of Pt atoms in the (111) surface. Since the Cu atoms are generated from a hot source, a fraction of the heat signal is due to radiation.…”

“…Alloying Cu with Pt has proven to be an effective way to tune the catalytic properties of Pt, and was a very thoroughly studied prototype system in basic research aimed at elucidating the relative importance of electronic effects versus ensemble effects in bimetallic catalysis. [1,6,14,15] Thus, well-ordered Cu overlayers and thin-film CuPt alloys on Pt(111) have been studied extensively in the past to further elucidate those effects and to clarify their unique adsorption and catalytic properties of small molecules such as oxygen, [16] CO, [17,18] CO 2 , [19,20] and formate. [21] To gain the first insight into the energetics of metalmetal bonding at the interface of core-shell bimetallic catalysts particles consisting of miscible metals in general, and Cu/Pt in particular, we study the adsorption and adhesion energies of Cu vapor deposited onto clean, wellordered Pt(111) at 300K by single crystal adsorption calorimetry (SCAC).…”

Effect of Pd Coordination and Isolation on the Catalytic Reduction of O2 to H2O2 over PdAu Bimetallic Nanoparticles

“…Characterization of Catalysts by Fourier Transform Infrared Spectroscopy of Adsorbed CO. The relative numbers of Pd and Au atoms exposed on each nanoparticle, the type of atoms to which these were coordinated, and differences between the electronic states of surface Pd atoms were examined by comparisons of FTIR spectra of adsorbed 12 CO and mixtures of adsorbed 12 CO and 13 CO. Samples were prepared by grinding catalysts (∼60 mg) into a fine powder and pelletizing the powder into self-supporting ∼20 mm diameter discs using a laboratory hydraulic press (Carver, model C).…”

“…Ltd.) with another stainless steel retaining ring on the cell exterior. Gaseous H 2 , 12 CO, He, and O 2 were introduced to the cell by digital mass flow controllers (Alicat, MC Series) mounted to a gas-handling manifold connected to the cell. In comparison, 13 CO (Sigma-Aldrich, 99% 13 C, <5% 18 O) was introduced by pulses from a custom-mixed lecture bottle (10% 13 CO in He).…”