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Insights into the Surface Electronic Structure and Catalytic Activity of InO x /Au(111) Inverse Catalysts for CO 2 Hydrogenation to Methanol
In this article, the direct conversion of carbon dioxide (CO 2 ) into methanol (CH 3 OH) via low-temperature hydrogenation is crucial for recycling anthropogenic CO 2 emissions and producing fuels or high value chemicals. Nevertheless, it continues to be a great challenge due to the trade-off between selectivity and catalytic activity. For CO 2 hydrogenation, In 2 O 3 catalysts are known for their high CH 3 OH selectivity. Subsequent studies explored depositing metals on In 2 O 3 to enhance CO 2 conversion. Despite extensive research on metal (M) supported In 2 O 3 catalysts, the role of In-M alloys and M/In 2 O 3 interfaces in CO 2 activation and CH 3 OH selectivity remains unclear. In this work, we have examined the behavior of In/Au(111) alloys and InO x /Au(111) inverse systems during CO 2 hydrogenation using synchrotron-based ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and catalytic tests in a batch reactor. Indium forms alloys with Au(111) after deposition. The In-Au(111) alloys display high reactivity towards CO 2 and can dissociate the molecule at room temperature to generate InO x nanostructures. At very low coverages of In (≤ 0.05 ML), the InO x nanostructures are not stable under CO 2 hydrogenation conditions and the active In-Au(111) alloys produces mainly CO and little methanol. An increase in indium coverage to 0.3 ML led to stable InOx nanostructures under CO 2 hydrogenation conditions. These InO x /Au(111) catalysts displayed a high selectivity (~ 80 %) towards CH 3 OH production and an activity for CO 2 conversion that was at least 10 times larger than that of plain In 2 O 3 or Cu(111) and Cu/ZnO(000$\overline{1)}$ benchmark catalysts. The results of AP-XPS show that InO x /Au(111) produces methanol via methoxy intermediates. Inverse oxide/metal catalysts containing InOx open up a possibility for improving CO 2 → CH 3 OH conversion in processes associated with the control of environmental pollution and the production of high value chemicals.
Tuning Nanoparticle Structure and Surface Strain for Catalysis Optimization
N/A
Well-defined surface catalytic sites for solar CO 2 reduction: heterogenized molecular catalysts and single atom catalysts
New photocatalysts can be prepared via heterogenization of molecular complexes and creation of atomically dispersed sites on surfaces. Structural investigation of such surface catalytic sites requires extensive use of spectroscopic techniques.
Magnetoelectric properties of (Pb{sub 0.60}Sr{sub 0.40})TiO{sub 3}-CFO composite thin film synthesized by metallo-organic decomposition
(Pb{sub 0.60}Sr{sub 0.40}) TiO{sub 3}-CFO composite thin films were grown on Pt/TiO{sub 2}/Si substrate by novel metallo-Organic process using spin coating technique. The structural, surface morphology and micro structural properties were confirmed by X-Ray diffraction (XRD), Raman spectroscopy, atomic force microscope (AFM) and TEM respectively. The lattice constant of the composite thin film crystallized in the pervoskite and spinel phase was 3.9531 and 8.571 Ǻ. Excellent ferroelectric behavior at 10V was observed, a room temperature magnetic hysteresis shows good results. The saturation magnetization value of the bilayer thin film is lower than that of the pure CFO film which is may be attributed to presence of non ferromagnetic PST layer A high initial behavior of dynamic ME response coefficient for the film was observed. The ME effect of the film strongly depends on the magnetic bias.
Gapless surface electronic structure of $1T–$$\mathrm{TiSe_2}$ in the distorted phase
Here, low temperature, high resolution angle resolved photoemission experiments performed on bulk $1T–$$\mathrm{TiSe_2}$ samples display conspicuous band folding as the only prominent signature of the periodic lattice distortion. The presence of a bulk electronic gap supporting a charge density wave phase is not confirmed in light of the new data. These observations cast serious doubts on the common belief of an electronic instability as the likely origin for the observed structural transition in $\mathrm{TiSe_2}$.
NESM TAG Meeting Notes
March 2015 NESM TAG Notes related to 1) Structure surface representation, 2) Structure-fluid coupling algorithm, 3) Coupled time integration scheme, 4) Coupling data exchange API, 5) Portability across platforms and builds, and 6) Testing and verification.
Theoretical and Experimental Investigations of the Physics of Crystalline Surfaces First Quarterly Report, 1 Feb. - 30 Apr. 1966
Crystalline surface physics - film layer structures, surface and interfacial energies, electron diffraction, and electron emission properties
Stress analysis for structures with surface cracks
Two basic forms of analysis, one treating stresses around arbitrarily loaded circular cracks, the other treating stresses due to loads arbitrarily distributed on the surface of a half space, are united by a boundary-point least squares method to obtain analyses for stresses from surface cracks in places or bars. Calculations were for enough cases to show how effects from the crack vary with the depth-to-length ratio, the fractional penetration ratio, the obliquity of the load, and to some extent the fractional span ratio. The results include plots showing stress intensity factors, stress component distributions near the crack, and crack opening displacement patterns. Favorable comparisons are shown with two kinds of independent experiments, but the main method for confirming the results is by wide checking of overall satisfaction of boundary conditions, so that external confirmation is not essential. Principles involved in designing analyses which promote dependability of the results are proposed and illustrated.
Figure control of flexible structures - Optical surfaces of thin deformable primary mirrors
Application of a modal control design technique to achieve discrete control of distributed parameter systems is considered. Results are presented for application of the design technique to achieve diffraction limited performance from the primary mirror of a space telescope and to provide flutter suppression for an aircraft wing.
Design, development and applications of novel techniques for studying surface mechanical properties
Research is reviewed for the adhesion, friction, and micromechanical properties of materials and examples of the results presented. The ceramic and metallic materials studied include silicon carbide, aluminum oxide, and iron-base amorphous alloys. The design and operation of a torsion balance adapted for study of adhesion from the Cavendish balance are discussed first. The pull-off force (adhesion) and shear force (friction) required to break the interfacial junctions between contacting surfaces of the materials were examined at various temperatures in a vacuum. The surface chemistry of the materials was analyzed by X-ray photoelectron spectroscopy. Properties and environmental conditions of the surface regions which affect adhesion and friction-such as surface segregation, composition, crystal structure, surface chemistry, and temperature were also studied.
Implications from Near-Shoemaker Imaging of Eros for Small-Scale Structure and Surface Sampling
What we know about asteroids has always been bifurcated by the enormous gap between astronomical studies of small, distant bodies, and the close-up laboratory measurements of hand-sample sized meteorites. The gulf has been narrowed somewhat by improvements in Earth-based astronomical techniques (e.g. Hubble Space Telescope, radar, adaptive optics) and especially by spacecraft fly-bys of asteroids. But the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker mission has gone considerably more in the direction of bridging the gap. Any consideration of intelligent sample-return from an asteroid must be based on the best possible knowledge of the asteroid at the spatial scales pertinent to operations at the asteroid and of the sample/s. Otherwise, we are in danger of succumbing to the 'Martian Horror Story' that Bruce Murray, in the 1960's, envisioned might impair our exploration of the surface of the red planet if we tried to land on it without first bolstering the information content of our database about Mars, especially at high resolutions. NEAR-Shoemaker is helping to bridge that gap in the case of Eros. The best resolution obtained by the Galileo spacecraft on Ida was 25 m/pixel. As of this writing, NEAR has already obtained images with resolutions at least five times better (information content 25 times better) and vastly better images may be available at the time of this Workshop from the late October low flyby. Already, we are seeing that the Martian horror story looks tame compared with Eros. Everywhere we have landed on Mars, the surface has been covered with rocks and boulders, with much higher spatial coverage than seen anywhere on the lunar surface. We have, in fact, been rather lucky that none of our Martian landers have tipped over so far, and there were justified fears in the early aftermath of last year's failure of Mars Polar Lander that it had suffered from inadequate high-resolution characterization of polar regions on Mars (the failure is now known to have had another cause). Eros looks potentially even more terrifying. Additional information is contained in the original extended abstract.
Investigation of Pore Size Effect On Spray Cooling Heat Transfer With Porous Tunnels
Previous studies have shown that spray cooling heat flux enhancement may be attained by using enhanced surface structures. However, most enhanced surface spray cooling studies have been limited to extended surfaces relative to the base surface. In this study, experiments were conducted to study the effects of pore size on spray cooling heat flux when using porous tunnels. The porous tunnels where placed sub-surface relative to the top of the heater block. Pores of varying size were machined in the top of the heater block leading into the sub-surface tunnels. Pore diameters varied between 0.25 mm and 1.0 mm. Each copper block had a projected cross-sectional area of 2.0 cm(sup 2). Measurements were also obtained on a heater block with a flat surface for baseline comparison purposes. A 2x2 nozzle array was used with PF-5060 as the working fluid. Thermal performance data was obtained under nominally degassed (chamber pressure of 41.4 kPa) conditions with a bulk fluid temperature of 20.5 "C. Results for both the study show that the highest critical heat flux (CHF) attained was 141 w/cm2 using pores 1.0 mm in diameter. This gave an enhancement of 75% relative to the flat surface case under nominally degassed conditions.
Proposal for Certifying Expandable Planetary Surface Habitation Structures
A factor-of-safety (FS) of 4.0 is currently used to design habitation structures made from structural soft goods. This approach is inconsistent with using a FS of 2.0 for metallic and polymeric composite pressure vessels as well as soft good structures such as space suits and parachutes. This inconsistency arises by using the FS to improperly account for the unknown effects of a variety of environmental and loading uncertainties. Using a 4.0 FS not only results in additional structural mass, it also makes it difficult to gain insight into the limitations of the material and/or product form and thus, it becomes difficult to make improvements. In order to bring consistency to the design and certification of expandable habitat structures, the approach used by the Federal Aviation Administration (FAA) to certify polymeric composite aircraft structures is used as a model and point of departure. A draft certification plan for Expandable Habitat Structures is developed in this paper and offered as an option for placing habitats made from soft goods on an equal footing with other structural implementations.
Chondritic Models of 4 Vesta: Comparison of Predicted Internal Structure and Surface Composition/Mineralogy with Data from the Dawn Mission
Understanding the physical and chemical processes which led to the formation of the terrestrial planets remains one of the principal challenges of the Earth and planetary science communities. However, direct traces of the earliest stages of planet building have generally been wiped out on larger bodies such as the Earth or Mars, obscuring our view of how that process occurred. On the other hand, the planet building process would appear to have been arrested prematurely in the region between Mars and Jupiter, now populated by several hundred thousand compositionally diverse objects that escaped accretion into larger planets. Of these, the asteroid 4 Vesta is of particular interest as it is large (520 km diameter), and known to have a basaltic surface dominated by pyroxenes [1, 2]. Furthermore, visible-IR spectra of Vesta obtained by ground and space-based telescopes are remarkably similar to laboratory spectra measured on meteorites of the Howardite-Eucrite-Diogenite clan (HED), leading to the paradigm that the HEDs came from Vesta [2]. Geochemical and petrological studies of the HEDs confirm the differentiated nature of the near-surface region of their parent body, and imply that crust extraction occurred well within the first 10Ma of solar system history [3]. Vesta is therefore a prime target for studies that aim to constrain the earliest stages of planet building, and for that reason it is currently the subject of the Dawn mission [4].