In situ/operando Mössbauer spectroscopy for probing heterogeneous catalysis

Zeng, Yaqiong; Li, Xuning; Wang, Junhu; Sougrati, Moulay Tahar; Huang, Yanqiang; Zhang, Tao; Liu, Bin

doi:10.1016/j.checat.2021.08.013

Cited by 30 publications

(25 citation statements)

References 66 publications

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“…The distributions show relative maxima at around 0.54 and 0.90 mm/s with an average value of 0.65 mm/s, which are characteristic of Fe 3+ in octahedral oxygen coordination. 72,73 This is consistent with the XPS data. The fitting to a distribution model as opposed to discrete one or two doublets indicates that while Fe 3+ ions adopt essentially identical octahedral sites, the electronic environments of the Fe 3+ ions experience perturbation from the nearest neighbor or next nearest neighbor ions.…”

Section: Resultssupporting

confidence: 90%

High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

et al. 2022

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O3-type layered oxide materials are considered to be a highly suitable cathode for sodium-ion batteries (NIBs) due to their appreciable specific capacity and energy density. However, rapid capacity fading caused by serious structural changes and interfacial degradation hampers their use. A novel Sn-modified O3-type layered NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode is presented, with improved high-voltage stability through simultaneous bulk Sn doping and surface coating in a scalable one-step process. The bulk substitution of Sn 4+ stabilizes the crystal structure by alleviating the irreversible phase transition and lattice structure degradation and increases the observed average voltage. In the meantime, the nanolayer Sn/Na/O composite on the surface effectively inhibits surface parasitic reactions and improves the interfacial stability during cycling. A series of Sn-modified materials are reported. An 8%-Sn-modified NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode exhibits a doubling in capacity retention increase after 150 cycles in the wide voltage range of 2.0–4.1 V vs Na/Na + compared to none, and 81% capacity retention is observed after 200 cycles in a full cell vs hard carbon. This work offers a facile process to simultaneously stabilize the bulk structure and interface for the O3-type layered cathodes for sodium-ion batteries and raises the possibility of similar effective strategies to be employed for other energy storage materials.

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Section: Resultssupporting

confidence: 90%

High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

et al. 2022

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“…The macroscale integral spectroscopic methods such as Mössbauer, [58,59] infrared, [60] and synchrotron X-ray absorption spectroscopy (XAS) [61][62][63] provide the electronic-level insight into SAC mechanism under a homogeneous modeling assumption. However, given practical systems with a structural diversity, where single atoms, clusters, and particles coexist, the spectroscopic methods unfortunately become weak to reflect the localized structure.…”

Section: Introductionmentioning

confidence: 99%

Direct Visualization of the Evolution of a Single‐Atomic Cobalt Catalyst from Melting Nanoparticles with Carbon Dissolution

Zhang

et al. 2022

Advanced Science

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Transition metal single-atom catalysts (SACs) are of immense interest, but how exactly they are evolved upon pyrolysis of the corresponding precursors remains unclear as transition metal ions in the complex precursor undergo a series of morphological changes accompanied with changes in oxidation state as a result of the interactions with the carbon support. Herein, the authors record the complete evolution process of Co SAC during the pyrolysis a Co/Zn-containing zeolitic imidazolate framework. Aberration-corrected environmental TEM coupled with in-situ EELS is used for direct visualization of the evolution process at 200-1000 °C. Dissolution of carbon into the nanoparticles of Co is found to be key to modulating the wetting behavior of nanoparticles on the carbon support; melting of Co nanoparticles and their motion within the zeolitic architecture leads to the etching of the framework structure, yielding porous C/N support onto which Co-single atoms reside. This uniquely structured Co SAC is found to be effective for the oxidation of a series of aromatic alkanes to produce selective ketones among other possible products. The carbon dissolution and melting/sublimation-driven structural dynamics of transition metal revealed here will expand the methodology in synthesizing SACs and other high-temperature processes.

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“…Undercoordinated ions residing along the edge, or at corners, of the layered double hydroxide structure are often viewed as the catalytically relevant sites. − Variations in measurement strategies have also revealed unexpected tetrahedrally coordinated sites, , the ability for elements such as iron and iridium to reside atop the basal plane of Ni(OH) 2 , systematic variations in iron electronic structures, ,, the presence of lattice strain due to ionic radius differences between nickel and iron, , and the possibility of iron redox activity . Analysis using advanced in-operando techniques has yielded some success in identifying sites that may have catalytic relevance. − Identification of such non-standard sites, however, has been relatively restricted to individual lines of research due to reliance on specialized characterization and analytical techniques. An understanding of the prevalence of such structural features and the role of synthetic conditions in their effective concentrations will assist in optimizing electrocatalysts’ performance and stability.…”

Section: Introductionmentioning

confidence: 99%

Linking Lattice Strain and Electron Transfer Kinetics in Crystalline Layered Double Hydroxides

Alsaç

Smith

2022

ACS Catal.

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The improved electrocatalytic property of disordered metal hydroxides relative to that of crystalline layered double hydroxides remains a poorly understood phenomenon. We use a hydrothermally synthesized series of mixed metal hydroxides to study these composition-dependent structural similarities and electrochemical behavior differences. X-ray diffraction, X-ray absorption spectroscopy, and Raman spectroscopy provide complementary perspectives on the structure of the Fe x Ni1–x (OH)2 series. These techniques reveal near quantitative incorporation of Fe(III) into the Ni(OH)2 lattice at low Fe-content but also that Fe(III) is distributed into a contaminating iron oxide phase and a non-traditional coordination environment atop the layered double hydroxide structure as the Fe-content increases. Systematic lattice contraction is observed with increasing Fe-content, similar to structurally disordered analogues, but the electrochemical behavior is markedly different. The characteristic anodic shift of pre-catalytic redox peaks does not occur, and electron transfer kinetics exhibit a much more gradual improvement. Measured Tafel slopes are found to possess a linear relationship with the O–Ni–O bond angles within the lattice across the full composition series. The asymmetric Marcus–Hush theory is used to explain this unexpected result, where Fe(III) ions systematically introduce a lattice strain that alters the reaction coordinate for the nickel oxidation reactions.

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In situ/operando Mössbauer spectroscopy for probing heterogeneous catalysis

Cited by 30 publications

References 66 publications

High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

Direct Visualization of the Evolution of a Single‐Atomic Cobalt Catalyst from Melting Nanoparticles with Carbon Dissolution

Linking Lattice Strain and Electron Transfer Kinetics in Crystalline Layered Double Hydroxides

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