Lithium monoxide anion (LiO–) has been generated in the gas phase and is found to be a stronger base than methyl anion (CHFormula). This makes LiO– the strongest base currently known, and it will be a challenge to produce a singly charged or multiply charged anion that is more basic. The experimental acidity of lithium hydroxide is {Delta}H°Formula = 425.7 ± 6.1 kcal·mol–1 (1 kcal = 4.184 kJ) and, when combined with results of high-level computations, leads to our best estimate for the acidity of 426 ± 2 kcal·mol–1.

The formation of alloys by adsorbing gold on a Pd(1 1 1) single crystal substrate and subsequently annealing to various temperatures is studied in an ultrahigh vacuum by means of Auger and X-ray photoelectron spectroscopy. The nature of the alloy surface is probed by CO chemisorption using temperature-programmed desorption and reflection-absorption infrared spectroscopy. It is found that gold grows in a layer-by-layer fashion on Pd(1 1 1) at 300 K, and starts to diffuse into the bulk after annealing to above not, vert, similar600 K. Alloy formation results in a not, vert, similar0.5 eV binding energy decrease of the Au 4f XPS signals and a binding energy increase of the Pd 3d features of not, vert, similar0.8 eV, consistent with results obtained for the bulk alloy. The experimentally measured CO desorption activation energies and vibrational frequencies do not correlate well with the surface sites expected from the bulk alloy composition but are more consistent with significant preferential segregation of gold to the alloy surface.

Bimetallic AuPd catalysts were prepared by deposition of bimetallic aqueous sols formed in different ways: (i) co-reduction of the precursor Au and Pd ions by Na-citrate/tannic acid mixture, (ii) reduction of Au(III) ions onto preformed Pd sol, and (iii) reduction of Pd(II) ions onto a preformed Au sol. The Au/TiO2 and Pd/TiO2 samples as references were prepared from their respective sols. The structure of the samples was characterized by XRF, XRD, XPS, TEM and CO chemisorption both in the as-prepared state and after calcination and reduction. The catalytic activities of the calcined/reduced catalysts in the CO oxidation were compared. The presence of bimetallic crystalline phases was evidenced in all three samples both in the as prepared and calcined/reduced states, however, various extents of Pd surface enrichment were determined. The catalytic activity of the bimetallic samples regardless of the preparation method, is about the same as that of the mixture of the monometallic samples. No significant synergism is suggested in the present bimetallic samples.

Pd, Au, and Pd-Au mixtures were deposited via physical vapor deposition onto a Mo(110) substrate, and the surface concentration and morphology of the Pd-Au mixtures were determined by low-energy ion scattering spectroscopy (LEISS), infrared absorption spectroscopy (IRAS), temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). Pd-Au mixtures form a stable alloy between 700 and 1000 K with substantial enrichment in Au compared to the bulk composition. Annealing a 1:1 Pd-Au mixture at 800 K leads to the formation of a surface alloy with a composition Au0.8Pd0.2 where Pd is predominantly surrounded by Au. The surface concentration of this isolated Pd site can be systematically controlled by altering the bulk Pd-Au alloy concentration.

We report the vapor phase synthesis and characterization of supported Pd, Au and unsupported bimetallic nanoparticle catalysts for CO oxidation. The approach utilized in the present work is based on the laser vaporization/controlled condensation technique which uniquely combines the features of pulsed laser vaporization with the controlled condensation process from the vapor phase to synthesize nanoparticle catalysts of controlled size and composition. The results indicate that supported Pd/CeO2, Au/CeO2, and unsupported bimetallic CuPd, CuAu, and AuPd nanoparticle catalysts exhibit excellent activity for CO oxidation. The significance of the current method lies mainly in its simplicity, flexibility and the control of the different factors that determine the activity of the nanoparticle catalysts.

The oxidation of CO on Pd(111) and Pd70Au30(111) has been studied under pressures upto 100 Torr. Gold is found to decrease the surface activity by inhibiting oxygen dissociation. For a sufficient conversion time depending on the CO coverage and the surface identity, a dramatic boost of activity occurs. This is ascribed to a switch from CO-induced inhibition of O2 adsorption to a regime determined by CO adsorption. The other kinetic features are explained by oxidation of palladium and adsorption-induced restructuring of the surfaces.

Pd-Ni catalysts supported on Al2O3 and (Ce,Zr)Ox/Al2O3, both in fresh and thermally aged states, were examined with the main aim of determining the effects of Ni and Ce-Zr mixed oxide on the catalytic activity for CO and C3H6 oxidation, and NO reduction reactions under stoichiometric conditions. For this purpose, catalytic activity results were analysed in conjunction with DRIFTS and XANES spectra recorded under reaction conditions to obtain information on the processes occurring in the catalysts during the course of the reactions. While a nickel-induced promotion of the formation of contacts between palladium and the Ce-Zr mixed oxides generally enhances the CO oxidation performance of the catalyst, it results detrimental to the NO reduction activity. This has been related to the higher difficulty in achieving the most active metallic palladium state for comparatively similar particle sizes in the presence of such contacts. Comparison of DRIFTS spectra under various reactant mixtures and between fresh and aged systems was shown to explain in a unique way the detrimental catalytic effects of hydrocarbon self-poisoning and sintering of the active components in the catalysts.

Fuel cells are appealing for a variety of energy needs, but the high materials and manufacturing costs have hampered their commercialization. The limited availability and the high cost of the currently used platinum catalysts, for example, pose a serious problem in their practical application. We report here non-platinum electrocatalyst systems, such as Pd-Co-Au and Pd-Ti, that are proposed from simple thermodynamic guidelines and selected by a rapid screening technique, which show electrochemical performance in proton exchange membrane fuel cells (PEMFC) similar to that found with commercial platinum catalysts. This finding opens up a new avenue to develop potentially less expensive electrocatalysts.

Pd–Ni catalysts supported on Al2O3, (Ce,Zr)Ox/Al2O3, and (Ce,Zr)Ox are characterized at a nanoscopic level using mainly electron microscopy-related techniques (HREM images, XEDS, and Z-contrast images/EELS spectra done with TEM and STEM instruments). The presence of rather homogeneous Ce–Zr mixed oxide nanostructures is revealed from analysis of HREM pictures. Analysis of the Pd–Ni/(Ce,Zr)Ox/Al2O3 system shows the existence of preferential interactions of Pd and Ni with the (Ce,Zr)Ox and Al2O3 components, respectively, as evidenced mainly by XEDS and confirmed by FMR. Dispersion states of the metals and particle size distributions of palladium are inferred from analysis of Z-contrast images and EELS spectra. The results are complemented by XPS and XAFS results used to analyse the chemical state of the metallic components in the catalysts and their dispersion over the different supports.

Pd–Ni catalysts supported on Al2O3, (Ce,Zr)Ox/Al2O3, and (Ce,Zr)Ox were examined with the principle objective of determining the effects of Ni on catalytic activity for CO oxidation and NO reduction reactions under stoichiometric conditions. Catalytic activity findings for the CO + O2 and CO + O2 + NO reactions were analyzed in conjunction with in situ DRIFTS and XANES results to obtain information on the processes occurring in the catalysts during the course of the reactions. The results reveal a significant dependence on the nature of the support in terms of the catalytic changes produced by nickel. In the absence of significant nickel-induced electronic perturbations of palladium, these are related to indirect effects on palladium distribution over the catalysts or to a certain impediment of the interactions between active palladium and Ce–Zr mixed-oxide components. Significant promotion of CO oxidation was observed for the (Ce,Zr)Ox/Al2O3-supported catalyst, which reveals a relevant role for the particle size of the nanostructured Ce–Zr mixed oxide in this reaction.