Stable single metal adatoms on oxide surfaces are of great interest for future applications in the field of catalysis. We studied iridium single atoms (Ir) supported on a FeO(001) single crystal, a model system previously only studied in ultra-high vacuum, to explore their behavior upon exposure to several gases in the millibar range (up to 20 mbar) utilizing ambient-pressure X-ray photoelectron spectroscopy. The Ir single adatoms appear stable upon exposure to a variety of common gases at room temperature, including oxygen (O), hydrogen (H), nitrogen (N), carbon monoxide (CO), argon (Ar), and water vapor. Changes in the Ir 4f binding energy suggest that Ir interacts not only with adsorbed and dissociated molecules but also with water/OH groups and adventitious carbon species deposited inevitably under these pressure conditions. At higher temperatures (473 K), iridium adatom encapsulation takes place in an oxidizing environment (a partial O pressure of 0.1 mbar). We attribute this phenomenon to magnetite growth caused by the enhanced diffusion of iron cations near the surface. These findings provide an initial understanding of the behavior of single atoms on metal oxides outside the UHV regime.
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http://dx.doi.org/10.1021/acs.jpcc.3c03097 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Physics and Astronomy, University of California, Irvine, CA 92697.
Understanding topological defects-controlled structural degradation of layered oxides-a key cathode material for high-performance lithium-ion batteries-plays a critical role in developing next-generation cathode materials. Here, by constructing a nanobattery in an electron microscope enabling atomic-scale monitoring of electrochemcial reactions, we captured the electrochemically driven atomistic dynamics and evolution of dislocations-a most important topological defect in material. We deciphered how dislocations nucleate, move, and annihilate within layered cathodes at the atomic scale.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
State Key Laboratory for Chemo/Biosensing and Chemometrics, Advanced Catalytic Engineering Research Center of the Ministry of Education and College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
The cobalt-nitrogen-carbon (Co─N─C) single-atom catalysts (SACs) are promising alternatives to precious metals for catalyzing the hydrogen evolution reaction (HER) and their activity is highly dependent on the coordination environments of the metal centers. Herein, a NaHCO etching strategy is developed to introduce abundant in-plane pores within the carbon substrates that further enable the construction of low-coordinated and asymmetric Co─N sites with nearby vacancy defects in a Co─N─C catalyst. This catalyst exhibits a high HER activity with an overpotential (η) of merely 78 mV to deliver a current density of 10 mA cm, a Tafel slope of 45.
View Article and Find Full Text PDFMicrosc Microanal
January 2025
Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstraße 1, Stuttgart 70569, Germany.
In the field of quantum materials, understanding anomalous behavior under charge degrees of freedom through bond formation is of fundamental importance, with two key concepts: Dimerization and charge order at different cation sites. The coexistence of both dimerization and charge ordering is unusually found in NaRu2O4, even in its metallic state at room temperature. Our work unveils the origin of the interplay of these effects within metallic single-crystalline NaRu2O4.
View Article and Find Full Text PDFMicrosc Microanal
January 2025
Department of Mathematics, University of South Carolina, 1523 Greene St, Columbia, SC 29208, USA.
We introduce a new approach to the numerical simulation of Scanning Transmission Electron Microscopy images. The Lattice Multislice Algorithm takes advantage of the fact that the electron waves passing through the specimen have limited bandwidth and therefore can be approximated very well by a low-dimensional linear space spanned by translations of a well-localized function. Just like in the PRISM algorithm recently published by C.
View Article and Find Full Text PDFJ Mol Model
January 2025
College of Electronics and Information, Xi'an Polytechnic University, Xian, People's Republic of China.
Context: The two-dimensional graphene/MoTe heterostructure holds extensive potential applications in optoelectronic devices, sensors, and catalysts. To expand its optical applications, this study systematically investigates the adsorption stability of metal atoms (Au, Pt, Pd, and Fe) on the graphene/MoTe and their influence on its optoelectronic properties employing first-principles methods. The findings indicate that after the adsorption of Au and Pd, the structure retains its direct bandgap properties, while the adsorption of Pt and Fe exhibits indirect bandgap characteristics.
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