Photon-In/Photon-Out Soft X-ray Spectroscopy at the TPS 45A Beamline

Dong, Chung‐Li; Chiou, J. W.; Tsai, Huang-Ming; Fu, Huang Wen; Lin, Hong‐Ji; Chen, C.T.; Pong, W. F.

doi:10.1080/08940886.2017.1289802

Cited by 5 publications

(5 citation statements)

References 21 publications

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“…The energy calibration for Mn K -edge XANES and EXAFS data was performed by measuring the Mn foil reference before and after the spectroscopic measurements. The valence state of the Mn was determined by plotting the peak position of edge threshold after taking the first derivative of the Mn K -edge XANES and comparing it with the reference samples Mn 2 O 3 and MnO 2 . − Ex-situ Mn L 3,2 -edge XANES was performed at the TLS 20A and Taiwan Photon Source (TPS) 45A2 TKU-endstation beamlines in total electron yield mode at the National Synchrotron Radiation Research Center (NSRRC), Taiwan. For the ex-situ Mn L 3,2 -edge XANES measurements, the working electrodes were prepared separately with corresponding redox potential, mounted on the sample holder, and quickly transferred to the ultrahigh-vacuum chamber of the soft X-ray beamline-endstation.…”

Section: Methodsmentioning

confidence: 99%

Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Yadav

Shelke

Wang

et al. 2023

ACS Appl. Energy Mater.

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Cryptomelane-type α-MnO 2 has a high specific capacitance and cyclic stability because of its combination of 1 × 1 and 2 × 2 tunnel structures that are formed from the edge-and corner-sharing octahedra. It, therefore, has the potential to host various cations, which improve its electrochemical properties. The Na incorporation provides an opportunity for charge compensation by forming mixed-valence Mn 3+ and Mn 4+ states in α-MnO 2 . This study shows that the incorporation of Na results in superior electrochemical properties by enhancing the specific capacitance and capacity retention of α-MnO 2 to 234.4 F g −1 and ∼96%, respectively. The electrochemical performance is improved following Na incorporation by the induced phase competition between α-MnO 2 and the induced β-MnO 2 , while the charge neutrality between Jahn−Teller (JT) active Mn 3+ and Mn 4+ ions is maintained. The formed Mn 3+ /Mn 4+ mixed-valence species increase the strength of the redox reaction at the electrode−electrolyte interface, as observed from the in-situ Mn K-edge X-ray absorption nearedge structure (XANES) and the extended X-ray absorption fine structure. Ex-situ Mn L 3,2 -edge XANES analysis further reveals that the introduction of e g from the Mn 3+ 3d orbitals causes electron transfer via O 2p states by establishing the double-exchange (DE) Mn 3+ −O−Mn 4+ interaction. This study suggests that the electron exchange also involves the super-exchange (SE) Mn 4+ −O−Mn 4+ interaction, based on field-dependent magnetization (M−H) measurement, which accelerates the redox reaction in α-MnO 2 . This work demonstrates that JT active Mn 3+ e g configuration is responsible for the great improvement of electrochemical properties that are induced by the incorporation and insertion/extraction of Na + ions with the charge/discharge process, which causes electron hopping between Mn 3+ /Mn 4+ and Mn 4+ through oxygen ligand by DE/SE in the α-MnO 2 .

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Section: Methodsmentioning

confidence: 99%

Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Yadav

Shelke

Wang

et al. 2023

ACS Appl. Energy Mater.

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“…In addition, a vibrating-sample magnetometer (VSM, Lake Shore 7400 system) was used to observe induced magnetization and M–H loop measurements under the magnetic field ( H ) up to 15 000 Oe. The soft X-ray experiments were performed at the TPS 45A2 beamline , of the National Synchrotron Radiation Research Center in Taiwan. The total electron yield method was used to measure the X-ray absorption and the X-ray magnetic circular dichroism across the Co and Fe L-edge, with left- and right-handed circularly polarized light along with an applied magnetic field of 1.5 T.…”

Section: Methodsmentioning

confidence: 99%

Polarized Hole Injection-induced Magnetic Enhancement in Carbon-Encapsulated Cobalt Ferrite Nanoparticles

Lee,

Hung,

Lin

et al. 2023

J. Phys. Chem. C

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Magnetic enhancement was observed in carbon-encapsulated cobalt ferrite (CoFe2O4) nanoparticles. The induced magnetic moment of the nanoparticles was estimated using a vibrating-sample magnetometer and corrected based on thermogravimetric loss. Notably, up to 25% magnetic enhancement was achieved via carbon encapsulation by low-temperature hydrothermal reactions. A systematic variation on Co L-edge absorption spectra revealed the introduction of valence holes owing to carbon encapsulation, and the hole injection was attributed to carbon–sp contact. X-ray magnetic circular dichroism indicates holes injected upon both Fe and Co ions. Specifically, it is observed that the injection of polarized holes into Co2+ ions at the octahedral site results in magnetic enhancement. A spin–split electronic structure analysis of CoFe2O4 based on density functional theory with Hubbard correction demonstrated that octahedral Co, which served as a minority hole reservoir, controlled the magnetic properties of the hybrid system.

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“…Zn L 3 -, V L 3,2 -, and O K edge XANES were obtained at TLS-BL 20A in surface-sensitive TEY mode, and Zn L 3 edge XANES was also obtained in TFY mode to differentiate between the surface and bulk contributions in spectra. O Kα XES was carried out at TPS-BL 45A2 with a high-resolution variable line spacing grating spectrometer …”

Section: Methodsmentioning

confidence: 99%

“…O Kα XES was carried out at TPS-BL 45A2 with a high-resolution variable line spacing grating spectrometer. 62 In situ illuminated XANES spectra were obtained with irradiation by an AM 1.5 sunlight simulator that was based on a 500 W Xe lamp. VB-PES spectra were obtained at TLS-BL 09A using a hemispherical analyzer to collect the photoelectrons, and the energy of the incident photons was set to 385.0 eV.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO₄ Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation

Wang

Chiou

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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Synchrotron-based X-ray spectroscopic and microscopic techniques are used to identify the origin of enhancement of the photoelectrochemical (PEC) properties of BiVO 4 (BVO) that is coated on ZnO nanodendrites (hereafter referred to as BVO/ ZnO). The atomic and electronic structures of core−shell BVO/ ZnO nanodendrites have been well-characterized, and the heterojunction has been determined to favor the migration of charge carriers under the PEC condition. The variation of charge density between ZnO and BVO in core−shell BVO/ZnO nanodendrites with many unpaired O 2p-derived states at the interface forms interfacial oxygen defects and yields a band gap of approximately 2.6 eV in BVO/ZnO nanocomposites. Atomic structural distortions at the interface of BVO/ZnO nanodendrites, which support the fact that there are many interfacial oxygen defects, affect the O 2p−V 3d hybridization and reduce the crystal field energy 10Dq ∼2.1 eV. Such an interfacial atomic/electronic structure and band gap modulation increase the efficiency of absorption of solar light and electron−hole separation. This study provides evidence that the interfacial oxygen defects act as a trapping center and are critical for the charge transfer, retarding electron−hole recombination, and high absorption of visible light, which can result in favorable PEC properties of a nanostructured core−shell BVO/ZnO heterojunction. Insights into the local atomic and electronic structures of the BVO/ZnO heterojunction support the fabrication of semiconductor heterojunctions with optimal compositions and an optimal interface, which are sought to maximize solar light utilization and the transportation of charge carriers for PEC water splitting and related applications.

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Photon-In/Photon-Out Soft X-ray Spectroscopy at the TPS 45A Beamline

Cited by 5 publications

References 21 publications

Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Polarized Hole Injection-induced Magnetic Enhancement in Carbon-Encapsulated Cobalt Ferrite Nanoparticles

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO₄ Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation

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Photon-In/Photon-Out Soft X-ray Spectroscopy at the TPS 45A Beamline

Cited by 5 publications

References 21 publications

Mn3+ eg Configuration and Electron Transfer in Na-Incorporating α-MnO2 to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Mn3+ eg Configuration and Electron Transfer in Na-Incorporating α-MnO2 to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Polarized Hole Injection-induced Magnetic Enhancement in Carbon-Encapsulated Cobalt Ferrite Nanoparticles

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO4 Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation

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Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Mn³⁺ e_g Configuration and Electron Transfer in Na-Incorporating α-MnO₂ to Improve Electrochemical Supercapacitor: An In Situ and Ex Situ X-ray Absorption Spectroscopic Investigation

Role of Interfacial Defects in Photoelectrochemical Properties of BiVO₄ Coated on ZnO Nanodendrites: X-ray Spectroscopic and Microscopic Investigation