Understanding electron irradiation effects is vital not only for reliable transmission electron microscopy characterization, but increasingly also for the controlled manipulation of 2D materials. The displacement cross sections of monolayer hexagonal boron nitride (hBN) are measured using aberration-corrected scanning transmission electron microscopy in near ultra-high vacuum at primary beam energies between 50 and 90 keV. Damage rates below 80 keV are up to three orders of magnitude lower than previously measured at edges under poorer residual vacuum conditions, where chemical etching appears to dominate. Notably, it is possible to create single vacancies in hBN using electron irradiation, with boron almost twice as likely as nitrogen to be ejected below 80 keV. Moreover, any damage at such low energies cannot be explained by elastic knock-on, even when accounting for the vibrations of the atoms. A theoretical description is developed to account for the lowering of the displacement threshold due to valence ionization resulting from inelastic scattering of probe electrons, modeled using charge-constrained density functional theory molecular dynamics. Although significant reductions are found depending on the constrained charge, quantitative predictions for realistic ionization states are currently not possible. Nonetheless, there is potential for defect-engineering of hBN at the level of single vacancies using electron irradiation.
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http://dx.doi.org/10.1002/smll.202301926 | DOI Listing |
Molecules
January 2025
Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
Rare earth phosphate (XPO) is an extremely important rare earth compound. It can exhibit excellent activity and stability in catalytic applications by modifying its inherent properties. Porous single-crystalline (PSC) PrPO and SmPO with a large surface area consist of ordered lattices and disordered interconnected pores, resulting in activity similar to nanocrystals and stability resembling bulk crystals.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Tananaev Institute of Chemistry-Subdivision of the Federal Research Centre "Kola Science Centre of the Russian Academy of Sciences" (ICT KSC RAS), Apatity 184209, Murmansk Region, Russia.
We proposed and investigated a refinement of technology for obtaining Mg-doped LiNbO (LN) crystals by co-doping it with B. LN:Mg (5.0 mol%) is now the most widely used material based on bulk lithium niobate.
View Article and Find Full Text PDFEnviron Sci Technol
January 2025
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
Pt/CeO single-atom catalysts are attractive materials for CO oxidation but normally show poor activity below 150 °C mainly due to the unicity of the originally symmetric PtO structure. In this work, a highly active and stable Pt/CeO single-site catalyst with only 0.1 wt % Pt loading, achieving a satisfied complete conversion of CO at 150 °C, can be obtained through fabricating asymmetric PtO-oxygen vacancies (O) dual-active sites induced by well-dispersed NbO clusters.
View Article and Find Full Text PDFAdv Mater
January 2025
State Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide & Agricultural Bioengineering, Ministry of Education, State-Local Joint Laboratory for Comprehensive Utilization of Biomass, Center for R&D of Fine Chemicals, Guizhou University, Guiyang, 550025, China.
The co-electrolysis of CO and NO to synthesize urea has become an effective pathway to alternate the conventional Bosch-Meiser process, while the complexity of C-/N-containing intermediates for C-N coupling results in the urea electrosynthesis of unsatisfactory efficiency. In this work, an electronic spin state modulation maneuver with oxygen vacancies (Ov) is unveiled to effectively meliorate the oriented generation of key intermediates NH and CO for C-N coupling, furnishing urea in ultrahigh yield of 2175.47 µg mg h and Faraday efficiency of 70.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Engineering Research Center of Advanced Rare Earth Materials, Department of Chemistry, Tsinghua University, Beijing 100084, China.
The side reactions accompanying the charging and discharging process, as well as the difficulty in decomposing the discharge product lithium peroxide, have been important issues in the research field of lithium-oxygen batteries for a long time. Here, single atom Ta supported by CoO hollow sphere was designed and synthesized as a cathode catalyst. The single atom Ta forms an electron transport channel through the Ta-O-Co structure to stabilize octahedral Co sites, forming strong adsorption with reaction intermediates and ultimately forming a film-like lithium peroxide that is highly dispersed.
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