Thermodynamically stable nanotips of Au–Mo alloy

Nomura, Kazuya; Nagao, Tadaaki; Cho, B. L.; Katsuda, Hitoshi; Matsumura, T.; Oshima, C.

doi:10.1116/1.3263248

Cited by 6 publications

(4 citation statements)

References 12 publications

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“…Recently, we examined Au–Mo alloy tips. We observed spontaneous nanopyramid growth and, by field emission spectroscopy (FES), detected conspicuous peaks characteristic of single‐atom electron sources . However, because of the weak W–Au and Au–Au bonding in the nanopyramids, we did not observe single‐atom termination by field ion microscopy (FIM).…”

Section: Introductionmentioning

confidence: 83%

Field electron emission from molybdenum platinum alloy tips

Nakajima

Ito

Cho

et al. 2011

Surface & Interface Analysis

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a Through annealing at 900-1000 K under ultrahigh vacuum, a nanopyramid terminated by a single atom was spontaneously grown on a Mo-Pt alloy tip surface. We observed single-atom termination of the pyramid by field ion microscopy and detected its characteristic features by field emission spectroscopy. Mo95%-Pt5% alloy tips were fabricated into single-atom terminated pyramids at a higher success rate than were Mo99%-Pt1% alloy tips, strongly suggesting that Pt segregation at the tip surface was crucial for single-atom termination. In addition, we found the Mo95%-Pt5% alloy tips to be self-repairing and demountable, which are common properties in single-atom termination of body-centered cubic metal tips covered with a face-centered cubic material.

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Section: Introductionmentioning

confidence: 83%

Field electron emission from molybdenum platinum alloy tips

Nakajima

Ito

Cho

et al. 2011

Surface & Interface Analysis

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“…The spatial resolution given by the microscope is obtained from the reconstructed image of the object. Usually, the low-energy electron source is an ultra-sharp field emission W tip but noble-metalcoated W tips 22 , alloy tips 23 or a carbon nanotube 24 have also been used. Here, a more bulky recently developed source 14 is used, based on the point emission from a mineral particle deposited on the apex of a 12µm diameter carbon fiber.…”

Section: Methodsmentioning

confidence: 99%

High spatial resolution detection of low-energy electrons using an event-counting method, application to point projection microscopy

Salançon

Degiovanni

Lapena

et al. 2018

Review of Scientific Instruments

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An event-counting method using a two-microchannel plate stack in a low-energy electron point projection microscope is implemented. 15 μm detector spatial resolution, i.e., the distance between first-neighbor microchannels, is demonstrated. This leads to a 7 times better microscope resolution. Compared to previous work with neutrons [Tremsin et al., Nucl. Instrum. Methods Phys. Res., Sect. A 592, 374 (2008)], the large number of detection events achieved with electrons shows that the local response of the detector is mainly governed by the angle between the hexagonal structures of the two microchannel plates. Using this method in point projection microscopy offers the prospect of working with a greater source-object distance (350 nm instead of 50 nm), advancing toward atomic resolution.

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“…In the past, Au-based systems were studied by FIM for various applications such as the study of long-range migration of self-interstitial atoms [224], phase transformation [225], precipitation in neutron-irradiated alloys [226], conductivity [227], or in the application of nano-tips to electron microscopy [228]. Even though these studies were not focused on catalysis, they proved the feasibility of imaging various Au-based alloys by FIM; alloys which are now used for catalysis applications: Au-Mo [228] for the reverse water-gas shift reaction [229,230] or as N 2 dissociation catalyst for the Haber-Bosch process [231], Au-Pt [224] for CO oxidation [49,232] and selective toluene oxidation [52], Au-Fe [226] for CO oxidation [233] and N 2 dissociation catalyst for the Haber-Bosch process [231], and Au-Cu [225,234] for the water gas-shift reaction [235,236] and CO oxidation [50].…”

Section: Perspectivesmentioning

confidence: 99%

Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies

et al. 2017

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Abstract:Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D structured materials. To improve the efficiency of such catalysts, a better understanding of the catalytic process is required, from both the kinetic and material viewpoints. The understanding of such processes can be achieved using environmental imaging techniques allowing the observation of catalytic processes under reaction conditions, so as to study the systems in conditions as close as possible to industrial conditions. This review focuses on the description of catalytic processes occurring on Au-based catalysts with selected in situ imaging techniques, i.e., PEEM/LEEM, FIM/FEM and E-TEM, allowing a wide range of pressure and material complexity to be covered. These techniques, among others, are applied to unravel the presence of spatiotemporal behaviours, study mass transport and phase separation, determine activation energies of elementary steps, observe the morphological changes of supported nanoparticles, and finally correlate the surface composition with the catalytic reactivity.

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Thermodynamically stable nanotips of Au–Mo alloy

Cited by 6 publications

References 12 publications

Field electron emission from molybdenum platinum alloy tips

Field electron emission from molybdenum platinum alloy tips

High spatial resolution detection of low-energy electrons using an event-counting method, application to point projection microscopy

Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies

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