The promotion effect of isolated potassium atoms with hybridized orbitals in catalytic oxidation

Xu, Fei; Huang, Zhiwei; Hu, Pengcheng; Chen, Yaxin; Zheng, Lei; Gao, Jiayi; Tang, Xingfu

doi:10.1039/c5cc02476e

Cited by 60 publications

(73 citation statements)

References 30 publications

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“…found that isolated Ca 2+ in the tunnels of hydroxyapatite showed high catalytic activity in the complete oxidation of HCHO because Ca 2+ could activate molecular oxygen . Our recent work also showed that individual K + of a single‐site catalyst with hybridized d–sp orbitals had a high electronic DOS and possessed excellent ability to activate both molecular oxygen and lattice oxygen, and thus, the catalyst showed high catalytic activity for HCHO oxidation . It should be mentioned that previous studies found that potassium exhibited promotion effects in the Fisher–Tropsch reaction and ammonia synthesis, and the promoting function of potassium mainly originated from the electron‐donating effects of potassium.…”

Section: Introductionmentioning

confidence: 74%

“…HMO can be indexed to a tetragonal structure with the I 4/ m space group (Figure S1 in the Supporting Information), and thus, HMO, constructed from MnO 6 octahedra, has 1D square tunnels of about 4.7×4.7 Å 2 along the [001] direction. The tunnel walls consist of lattice oxygen with sp 3 hybridization; these lattice oxygen ions use three sp 3 orbitals to bond to three Mn 4+ , and another sp 3 orbital occupied by lone‐pair electrons can donate electrons to unoccupied orbitals of anchored metals, such as Ag and K + …”

Section: Resultsmentioning

confidence: 99%

“…The results are in agreement with the conclusion reached from SXRD refinement analyses that the alkali‐metal ions are arranged at an alternate stacking model along the HMO tunnel direction. Thus, the alkali‐metal ions are located at isolated states and the single alkali‐metal ions are exposed on the HMO tunnel openings to form “single‐atom” alkali‐metal catalysts . Furthermore, the EXAFS data of the single‐atom alkali‐metal catalysts are distinctly different from those of KCl and RbOH.…”

Section: Resultsmentioning

confidence: 99%

“…The K/Mn or Rb/Mn molar ratios obtained from EDX analyses determine the formulas to be K 0.9 Mn 8 O 16 and Rb 1.0 Mn 8 O 16 , which are in agreement with the results obtained by X‐ray fluorescence spectroscopy (XRF) analyses. Consequently, the HMO tunnels are filled with alkali‐metal ions, and alkali‐metal ions are exposed on the HMO(001) planes, as modeled in the insets of Figure d and f . These single alkali‐metal ions are anchored on oxygen cavity sites consisting of four surface sp 3 ‐oxygen ions.…”

Section: Resultsmentioning

confidence: 99%

“…Occasionally, alkali metals and alkaline‐earth metals, such as K + and Ca 2+ , atomically dispersed and with a high electron density of states (DOS), are highly active for the catalytic oxidation of HCHO . For instance, Han et al.…”

Section: Introductionmentioning

confidence: 99%

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Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Gao

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et al. 2017

Chemistry A European J

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Alkali-metal ions often act as promoters rather than active components due to their stable outermost electronic configurations and their inert properties in heterogeneous catalysis. Herein, inert alkali-metal ions, such as K and Rb , are activated by electron transfer from a Hollandite-type manganese oxide (HMO) support for HCHO oxidation. Results from synchrotron X-ray diffraction, absorption, and photoelectron spectroscopies demonstrate that the electronic density of states of single alkali-metal adatoms is much higher than that of K or Rb , because electrons transfer from manganese to the alkali-metal adatoms through bridging lattice oxygen atoms. Electron transfer originates from the interactions of alkali metal d-sp frontier orbitals with lattice oxygen sp orbitals occupied by lone-pair electrons. Reaction kinetics data of HCHO oxidation reveal that the high electronic density of states of single alkali-metal adatoms is favorable for the activation of molecular oxygen. Mn L -edge and O K-edge soft-X-ray absorption spectra demonstrate that lattice oxygen partially gains electrons from the Mn e orbitals, which leads to the upshift in energy of lattice oxygen orbitals. Therefore, the facile activation of molecular oxygen by the electron-abundant alkali-metal adatoms and active lattice oxygen are responsible for the high catalytic activity in complete oxidation of HCHO. This work could assist the design of efficient and cheap catalysts by tuning the electronic states of active components.

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Section: Introductionmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Gao

Chen

Wan

et al. 2017

Chemistry A European J

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Surface Co‐Modification of Halide Anions and Potassium Cations Promotes High‐Rate CO₂‐to‐Ethanol Electrosynthesis

et al. 2022

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The high‐rate electrochemical CO2 conversion to ethanol with high partial current density is attractive but challenging, which requires competing with other reduction products as well as hydrogen evolution. This work demonstrates the in situ reconstruction of KCuF3 perovskite under CO2 electroreduction conditions to fabricate a surface fluorine‐bonded, single‐potassium‐atom‐modified Cu(111) nanocrystal (K–F–Cu–CO2). Density functional theory calculations reveal that the co‐modification of both F and K atoms on the Cu(111) surface can promote the ethanol pathway via stabilization of the CO bond and selective hydrogenation of the CC bond in the CH2CHO* intermediate, while the single modification of either F or K is less effective. The K–F–Cu–CO2 electrocatalyst exhibits an outstanding CO2‐to‐ethanol partial current density of 423 ± 30 mA cm−2 with the corresponding Faradaic efficiency of 52.9 ± 3.7%, and a high electrochemical stability at large current densities, thus suggesting an attractive means of surface co‐modification of halide anions and alkali‐metal cations on Cu catalysts for high‐rate CO2‐to‐ethanol electrosynthesis.

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Thermocatalytic Degradation of Gaseous Formaldehyde Using Transition Metal‐Based Catalysts

2023

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Formaldehyde (HCHO: FA) is one of the most abundant but hazardous gaseous pollutants. Transition metal oxide (TMO)-based thermocatalysts have gained much attention in its removal due to their excellent thermal stability and cost-effectiveness. Herein, a comprehensive review is offered to highlight the current progress in TMO-based thermocatalysts (e.g., manganese, cerium, cobalt, and their composites) in association with the strategies established for catalytic removal of FA. Efforts are hence made to describe the interactive role of key factors (e.g., exposed crystal facets, alkali metal/nitrogen modification, type of precursors, and alkali/acid treatment) governing the catalytic activity of TMO-based thermocatalysts against FA. Their performance has been evaluated further between two distinctive operation conditions (i.e., low versus high temperature) based on computational metrics such as reaction rate. Accordingly, the superiority of TMO-based composite catalysts over mono-and bi-metallic TMO catalysts is evident to reflect the abundant surface oxygen vacancies and enhanced FA adsorptivity of the former group. Finally, the present challenges and future prospects for TMO-based catalysts are discussed with respect to the catalytic oxidation of FA. This review is expected to offer valuable information to design and build high performance catalysts for the efficient degradation of volatile organic compounds.

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The promotion effect of isolated potassium atoms with hybridized orbitals in catalytic oxidation

Cited by 60 publications

References 30 publications

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Surface Co‐Modification of Halide Anions and Potassium Cations Promotes High‐Rate CO₂‐to‐Ethanol Electrosynthesis

Thermocatalytic Degradation of Gaseous Formaldehyde Using Transition Metal‐Based Catalysts

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The promotion effect of isolated potassium atoms with hybridized orbitals in catalytic oxidation

Cited by 60 publications

References 30 publications

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Surface Co‐Modification of Halide Anions and Potassium Cations Promotes High‐Rate CO2‐to‐Ethanol Electrosynthesis

Thermocatalytic Degradation of Gaseous Formaldehyde Using Transition Metal‐Based Catalysts

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Surface Co‐Modification of Halide Anions and Potassium Cations Promotes High‐Rate CO₂‐to‐Ethanol Electrosynthesis