There is an ongoing effort to replace rare and expensive noble-element catalysts with more abundant and less expensive transition metal oxides. With this goal in mind, the intrinsic defects of a rhombohedral perovskite-like structure of LaMnO and their implications on CO catalytic properties were studied. Surface thermodynamic stability as a function of pressure (P) and temperature (T) were calculated to find the most stable surface under reaction conditions (P=0.2 atm, T=323 K to 673 K). Crystallographic planes (100), (111), (110), and (211) were evaluated and it was found that (110) with MnO termination was the most stable under reaction conditions. Adsorption energies of O and CO on (110) as well as the effect of intrinsic defects such as Mn and O vacancies were also calculated. It was found that O vacancies favor the interaction of CO on the surface, whereas Mn vacancies can favor the formation of carbonate species.
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http://dx.doi.org/10.1002/cphc.202200152 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Hubei Longzhong Laboratory, Wuhan University of Technology, Xiangyang Demonstration Zone, Xiangyang 441000, China.
Materials with high crystallographic symmetry are supposed to be good thermoelectrics because they have high valley degeneracy () and superb carrier mobility (μ). Binary GeSe crystallizes in a low-symmetry orthorhombic structure accompanying the stereoactive 4s lone pairs of Ge. Herein, we rationally modify GeSe into a high-symmetry rhombohedral structure by alloying with GeTe based on the valence-shell electron-pair repulsion theory.
View Article and Find Full Text PDFLangmuir
December 2024
School of Chemical Engineering and Energy Technology & School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, PR China.
Sodium manganese hexacyanoferrate, also called Prussian white (PW), has attracted much attention as a promising cathode material for Na-ion batteries due to its high-voltage platform and inexpensive elemental composition. However, their parasitic vacancies and water molecules often deteriorate the electrochemical performance. Proper regulation of such defects in scale-up preparation is still a challenge.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Interdisciplinary Materials Research Center, School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai, 201804, China.
Superior electronic performance due to the highly degenerated Σ valence band (N∼12) makes rhombohedral GeTe a promising low-temperature (<600 K) thermoelectric candidate. Minimizing lattice thermal conductivity (κ) is an essential route for enhancing thermoelectric performance, but the temperature-dependent κ, corelated to T, makes its reduction difficult at low temperature. In this work, a room-temperature κ of ≈0.
View Article and Find Full Text PDFNat Commun
October 2024
Department of Mathematics and Physics, Università Cattolica del Sacro Cuore, Brescia, Italy.
Avalanche resistive switching is the fundamental process that triggers the sudden change of the electrical properties in solid-state devices under the action of intense electric fields. Despite its relevance for information processing, ultrafast electronics, neuromorphic devices, resistive memories and brain-inspired computation, the nature of the local stochastic fluctuations that drive the formation of metallic regions within the insulating state has remained hidden. Here, using operando X-ray nano-imaging, we have captured the origin of resistive switching in a VO-based device under working conditions.
View Article and Find Full Text PDFMolecules
August 2024
Institute of Geotechnics of Slovak Academy of Sciences, 45, Watsonova Str., 04001 Košice, Slovakia.
Binary AsSe alloys from the border of a glass-forming region (65 < < 70) subjected to nanomilling in dry and dry-wet modes are characterized by the XRPD, micro-Raman scattering (micro-RS) and revised positron annihilation lifetime (PAL) methods complemented by a disproportionality analysis using the quantum-chemical cluster modeling approach. These alloys are examined with respect to tetra-arsenic biselenide AsSe stoichiometry, realized in glassy g-AsSe, glassy-crystalline g/c-AsSe and glassy-crystalline g/c-AsSe. From the XRPD results, the number of rhombohedral As and cubic arsenolite AsO phases in As-Se alloys increases after nanomilling, especially in the wet mode realized in a PVP water solution.
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