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The photoelectron momentum microscope (PMM) in operation at BL6U, an undulator-based soft x-ray beamline at the UVSOR Synchrotron Facility, offers a new approach for μm-scale momentum-resolved photoelectron spectroscopy (MRPES). A key feature of the PMM is that it can very effectively reduce radiation-induced damage by directly projecting a single photoelectron constant energy contour in reciprocal space with a radius of a few Å-1 or real space with a radius of a few 100 μm onto a two-dimensional detector. This approach was applied to three-dimensional valence band structure E(k) and E(r) measurements ("stereography") as functions of photon energy (hν), its polarization (e), detection position (r), and temperature (T). In this study, we described some examples of possible measurement techniques using a soft x-ray PMM. We successfully applied this stereography technique to μm-scale MRPES to selectively visualize the single-domain band structure of twinned face-centered-cubic Ir thin films grown on Al2O3(0001) substrates. The photon energy dependence of the photoelectron intensity on the Au(111) surface state was measured in detail within the bulk Fermi surface. By changing the temperature of 1T-TaS2, we clarified the variations in the valence band dispersion associated with chiral charge-density-wave phase transitions. Finally, PMMs for valence band stereography with various electron analyzers were compared, and the advantages of each were discussed.
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http://dx.doi.org/10.1063/5.0154156 | DOI Listing |
J Colloid Interface Sci
December 2024
School of Chemical Engineering, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia. Electronic address:
Photocatalytic oxygen evolution reaction (OER) is pivotal for sustainable energy systems yet lacks high-performance catalysts capable of strong visible light absorption, robust charge dynamics, fast reaction kinetics, and high oxidation capability. Herein, we report the multiscale optimization of carbon nitride through the construction of porous curled carbon nitride nanosheets (CNA-B30) incorporating boron center/cyano group Lewis acid-base pairs (LABPs). The unique chemical and structural features of CNA-B30 extended the photoabsorption edges of π → π* and n → π* electronic transitions to 470 nm and 715 nm, respectively.
View Article and Find Full Text PDFAcc Chem Res
December 2024
Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, United States.
ConspectusThe surface of a catalyst is crucial for understanding the mechanisms of catalytic reactions at the molecular level and developing new catalysts with higher activity, selectivity, and durability. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) is a technique studying the surface of a sample in the gas phase, mainly identifying chemical identity, analyzing oxidation state, and measuring surface composition.In the last decade, numerous photoelectron spectroscopic methods for fundamental studies of key topics in catalysis using AP-XPS have been developed.
View Article and Find Full Text PDFDalton Trans
December 2024
Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
Aquatic biota and human health are seriously threatened by the dramatic rise in antibiotics in environmental matrices. In this regard, the present study aims to improve knowledge of the combined effects of heterojunction design and defect engineering on the photocatalytic degradation of pharmaceuticals in aqueous matrices. Advantageously, the positioning of the valence band (VB) and conduction band (CB) levels of S@g-CN, being higher than those of BiMoO, demonstrates the feasibility of forming a type-II heterojunction between these materials.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
South China University of Technology, School of Environment and Energy, Room 316, B5 Building, South China University of Technology, Guangzhou Higher Education Mega Center, 510006, Guangzhou, CHINA.
Na4Fe3(PO4)2P2O7 (NFPP) has been regarded as the promising cathode material for sodium-ion batteries (SIBs). However, the practical applications of NFPP are hindered by its high-volume changes, poor intrinsic electron conductivity and sluggish Na+ ions diffusion kinetics. Herein, a spray-drying and solid-state reaction method have been utilized to fabricate the spherical trace amount Mg/Cu co-doped Na4Fe3(PO4)2P2O7 (NFMCPP).
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States.
The catalytic behavior of a material is influenced by ensembles─the geometric configuration of atoms on the surface. In conventional material systems, ensemble effects and the electronic structure are coupled because these strategies focus on varying the material composition, making it difficult to understand the role of ensembles in isolation. This study introduces a methodology that separates geometric effects from the electronic structure.
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