Characterization of Supported Metal Single‐Atom Catalysts

Zhang, Lei; Doyle‐Davis, Kieran; Sun, Xueliang

doi:10.1002/9783527830169.ch5

Cited by 7 publications

(7 citation statements)

References 81 publications

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“…For the first time, Tao Zhang confirmed the presence of a SA entity supported on FeO x using aberration-corrected high-angle annular dark-field imaging-scanning transmission electron microscopy (AC-HAADF-STEM) . The SACs characterization techniques can be broadly divided into two subdomains: (1) imaging, which includes direct observation of SAs, i.e., AC-HAADF-STEM and scanning tunneling microscopy (STM) and (2) spectroscopic techniques, which provide auxiliary evidence of their presence and chemical environment, i.e., X-ray absorption spectroscopy (XAS), electron energy loss spectroscopy (EELS), CO-DRIFT, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy, and Mössbauer spectra. , HAADF-STEM utilizes an annular detector to collect scattered electrons around the beam at a very high angle. Due to the collection of more electrons, the signal intensity and concomitantly the image quality are higher compared to conventional TEM dark-field imaging using an objective aperture.…”

Section: Characterization Of Sacsmentioning

confidence: 99%

“…Furthermore, the IS shift from 0.77 to 0.39 mm s –1 depicts an overlap between the Fe 3d orbital and O antibonding π* orbitals, resulting into shortened Fe–N bond lengths and movement of Fe 2+ inside the N–Fe II N 4 plane in O 2 – –Fe II N 5 . Other in situ approaches sporadically used to investigate SACs reaction mechanism are in situ EPR, mass spectrometry, SERS, and in situ NMR. , …”

Section: Characterization Of Sacsmentioning

confidence: 99%

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Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

Kumar

Al‐Attas

et al. 2022

ACS Nano

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Direct conversion of methane (CH 4 ) to C 1−2 liquid oxygenates is a captivating approach to lock carbons in transportable value-added chemicals, while reducing global warming. Existing approaches utilizing the transformation of CH 4 to liquid fuel via tandemized steam methane reforming and the Fischer−Tropsch synthesis are energy and capital intensive. Chemocatalytic partial oxidation of methane remains challenging due to the negligible electron affinity, poor C−H bond polarizability, and high activation energy barrier. Transition-metal and stoichiometric catalysts utilizing harsh oxidants and reaction conditions perform poorly with randomized product distribution. Paradoxically, the catalysts which are active enough to break C−H also promote overoxidation, resulting in CO 2 generation and reduced carbon balance. Developing catalysts which can break C−H bonds of methane to selectively make useful chemicals at mild conditions is vital to commercialization. Single atom catalysts (SACs) with specifically coordinated metal centers on active support have displayed intrigued reactivity and selectivity for methane oxidation. SACs can significantly reduce the activation energy due to induced electrostatic polarization of the C−H bond to facilitate the accelerated reaction rate at the low reaction temperature. The distinct metal−support interaction can stabilize the intermediate and prevent the overoxidation of the reaction products. The present review accounts for recent progress in the field of SACs for the selective oxidation of CH 4 to C 1−2 oxygenates. The chemical nature of catalytic sites, effects of metal−support interaction, and stabilization of intermediate species on catalysts to minimize overoxidation are thoroughly discussed with a forward-looking perspective to improve the catalytic performance.

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Section: Characterization Of Sacsmentioning

confidence: 99%

Section: Characterization Of Sacsmentioning

confidence: 99%

Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

Kumar

Al‐Attas

et al. 2022

ACS Nano

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“…As STEM-HAADF provides only a very local analysis of the samples (poor statistic value), the catalyst series was also characterized by XPS and XAS, two reference techniques for metal-supported SA characterization. [21] XPS analyses were performed on all four samples with introduction of the samples by an Ar-filled transfer vessel from a glove box under a controlled argon atmosphere; any air oxidation of these samples can be excluded. Figure 3 shows the deconvolution of the Pd 3d spectra of the four catalysts (results from the deconvolution are given in Table S1).…”

Section: Resultsmentioning

confidence: 99%

Adjustment of the Single Atom/Nanoparticle Ratio in Pd/CNT Catalysts for Phenylacetylene Selective Hydrogenation

et al. 2023

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Pd/C catalysts are widely used for hydrogenation reactions in the chemical industry. One of the reasons for their high activity is the ability of Pd nanoparticles (PdNP) to dissociate H2 and promote H‐spillover. Nevertheless, for selective hydrogenation unpromoted Pd/C catalysts show disappointing results. The use of supported Pd single atom (PdSA) catalysts permits to achieve high selectivity. However, PdSA show low activity because they have difficulty in activating H2. A cooperative catalysis between PdNP and PdSA operates for the hydrogenation of alkenes thanks to the H‐spillover, which makes it possible to obtain active isolated PdSA−H species. Here, we present experimental and computational results obtained for phenylacetylene hydrogenation on Pd/CNT catalysts showing different PdSA/PdNP ratios. Tuning this ratio allows doubling the activity while reaching high selectivity to styrene at high conversion. DFT calculations suggest that the first coordination sphere of PdSA has a pronounced effect on their reactivity.

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“…The structure of the diatomic material was characterized by spherical aberration electron microscope, synchronous radiation, Mössbauer spectrum, and other means. [ 7,117 ] Fe and Co bonded and coordinated with the surrounding N. The theoretical calculation shows that the existence of FeCo bond is more conducive to the fracture of OO bond, and this structure makes the catalyst have high activity in the oxygen reduction reaction. [ 118–120 ] The excellent performance of exhibiting a half‐wave potential of 0.863 V, an initial potential of 1.06 V, a current density of 2.842 mA cm −2 at 0.9 V, and a stable cycle of 50 000 cycles in the acidic oxygen reduction reaction is exhibited.…”

Section: Preparation Strategy Of Diatomic Catalystmentioning

confidence: 99%

“…XPS has also been used for the quantification of elements in SACs. [117,162] 4) The calculation simulates the existence state of diatomic and its interaction with the carrier, that is, DFT (see Figure 38 for details).…”

Section: Characterization Technology Of Diatomic Catalystmentioning

confidence: 99%

Recent Progress of Diatomic Catalysts: General Design Fundamentals and Diversified Catalytic Applications

2022

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In recent years, some experiments and theoretical work have pointed out that diatomic catalysts not only retain the advantages of monoatomic catalysts, but also introduce a variety of interactions, which exceed the theoretical limit of catalytic performance and can be applied to many catalytic fields. Here, the interaction between adjacent metal atoms in diatomic catalysts is elaborated: synergistic effect, spacing enhancement effect (geometric effect), and electronic effect. With regard to the classification and characterization of various new diatomic catalysts, diatomic catalysts are classified into four categories: heteronuclear/homonuclear, with/without carbon carriers, and their characterization measures are introduced and explained in detail. In the aspect of preparation of diatomic catalysts, the widely used atomic layer deposition method, metal–organic framework derivative method, and simple ball milling method are introduced, with emphasis on the formation mechanism of diatomic catalysts. Finally, the effective control strategies of four diatomic catalysts and the key applications of diatomic catalysts in electrocatalysis, photocatalysis, thermal catalysis, and other catalytic fields are given.

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Characterization of Supported Metal Single‐Atom Catalysts

Cited by 7 publications

References 81 publications

Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

Adjustment of the Single Atom/Nanoparticle Ratio in Pd/CNT Catalysts for Phenylacetylene Selective Hydrogenation

Recent Progress of Diatomic Catalysts: General Design Fundamentals and Diversified Catalytic Applications

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