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The superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet.

Li Y, Sun Q - Sci Rep (2014)

Bottom Line: Two-dimensional organometallic sheets containing regularly and separately distributed transition atoms (TMs) have received tremendous attentions due to their flexibility in synthesis, well-defined geometry and the promising applications in hydrogen storage, electronic circuits, quantum Hall effect, and spintronics.Here for the first time we present a study on the superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet proceeding first via Langmuir-Hinshelwood (LH) mechanism and then via Eley-Rideal (ER) mechanism.Compared to the noble metal based catalysts or graphene supported catalysts, our studied system has following unique features: without poisoning effect and clustering problem, having comparable reaction energy barrier for low-temperature oxidation, and low cost for large-scale catalytic CO oxidation in industry.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.

ABSTRACT
Two-dimensional organometallic sheets containing regularly and separately distributed transition atoms (TMs) have received tremendous attentions due to their flexibility in synthesis, well-defined geometry and the promising applications in hydrogen storage, electronic circuits, quantum Hall effect, and spintronics. Here for the first time we present a study on the superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet proceeding first via Langmuir-Hinshelwood (LH) mechanism and then via Eley-Rideal (ER) mechanism. Compared to the noble metal based catalysts or graphene supported catalysts, our studied system has following unique features: without poisoning effect and clustering problem, having comparable reaction energy barrier for low-temperature oxidation, and low cost for large-scale catalytic CO oxidation in industry.

No MeSH data available.


Related in: MedlinePlus

Schematic energy profile and the corresponding local configurations along the Eley-Rideal step.Both top (upper panel) and side views (lower panel) are illustrated. All energies are given with respect to the reference energy of the coadsorbed state for CO and O on a 2D CrPc sheet.
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f5: Schematic energy profile and the corresponding local configurations along the Eley-Rideal step.Both top (upper panel) and side views (lower panel) are illustrated. All energies are given with respect to the reference energy of the coadsorbed state for CO and O on a 2D CrPc sheet.

Mentions: Figure 4 and Figure 5 show the energy profiles of MEPs via LH and ER mechanisms as well as the side and top views of the local configurations of the adsorbates along the MEPs, respectively. Upon coadsorption of CO and O2, the CO and O2 molecules approach each other to form the first transition state (TS1), with an energy barrier of 0.55 eV along the reaction pathway. Passing over TS1, an peroxide-type intermediate state (MS) is formed, which is a slight endothermic process with the reaction energy of 0.05 eV for CO + O2 → OOCO. Mediated by the central Cr atom, the O-O bond length of the peroxide-type intermediate elongates continuously and passes over the second transition state (TS2) with a substantially low energy barrier of only 0.09 eV to come to the final state (FS), releasing a large energy of 4.52 eV in the overall LH process. The resulting CO2 molecule is easy to desorb from the substrate due to the weaker interaction between CO2 and the substrate, leaving an atomic O strongly interacting with the Cr atom. Such an activated surface O atom can readily bind another CO molecule to form another intermediate state, surmounting an energy barrier of 0.46 eV. The intermediate state will soon turn to the final state without any energy barrier, regenerating a 2D CrPc sheet with another CO2 released. The highest energy barrier of this catalytic cycle is therefore only 0.55 eV, which is considerably lower than that of Fe-N4 porphyrin-like graphene and carbon nanotube at the same calculation level of theory16. Such disparate energy barriers between Cr and Fe containing porphyrin-like frameworks further corroborate the fact that apposite selection of central metal atoms can achieve an outstanding performance in catalytic processes.


The superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet.

Li Y, Sun Q - Sci Rep (2014)

Schematic energy profile and the corresponding local configurations along the Eley-Rideal step.Both top (upper panel) and side views (lower panel) are illustrated. All energies are given with respect to the reference energy of the coadsorbed state for CO and O on a 2D CrPc sheet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3924217&req=5

f5: Schematic energy profile and the corresponding local configurations along the Eley-Rideal step.Both top (upper panel) and side views (lower panel) are illustrated. All energies are given with respect to the reference energy of the coadsorbed state for CO and O on a 2D CrPc sheet.
Mentions: Figure 4 and Figure 5 show the energy profiles of MEPs via LH and ER mechanisms as well as the side and top views of the local configurations of the adsorbates along the MEPs, respectively. Upon coadsorption of CO and O2, the CO and O2 molecules approach each other to form the first transition state (TS1), with an energy barrier of 0.55 eV along the reaction pathway. Passing over TS1, an peroxide-type intermediate state (MS) is formed, which is a slight endothermic process with the reaction energy of 0.05 eV for CO + O2 → OOCO. Mediated by the central Cr atom, the O-O bond length of the peroxide-type intermediate elongates continuously and passes over the second transition state (TS2) with a substantially low energy barrier of only 0.09 eV to come to the final state (FS), releasing a large energy of 4.52 eV in the overall LH process. The resulting CO2 molecule is easy to desorb from the substrate due to the weaker interaction between CO2 and the substrate, leaving an atomic O strongly interacting with the Cr atom. Such an activated surface O atom can readily bind another CO molecule to form another intermediate state, surmounting an energy barrier of 0.46 eV. The intermediate state will soon turn to the final state without any energy barrier, regenerating a 2D CrPc sheet with another CO2 released. The highest energy barrier of this catalytic cycle is therefore only 0.55 eV, which is considerably lower than that of Fe-N4 porphyrin-like graphene and carbon nanotube at the same calculation level of theory16. Such disparate energy barriers between Cr and Fe containing porphyrin-like frameworks further corroborate the fact that apposite selection of central metal atoms can achieve an outstanding performance in catalytic processes.

Bottom Line: Two-dimensional organometallic sheets containing regularly and separately distributed transition atoms (TMs) have received tremendous attentions due to their flexibility in synthesis, well-defined geometry and the promising applications in hydrogen storage, electronic circuits, quantum Hall effect, and spintronics.Here for the first time we present a study on the superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet proceeding first via Langmuir-Hinshelwood (LH) mechanism and then via Eley-Rideal (ER) mechanism.Compared to the noble metal based catalysts or graphene supported catalysts, our studied system has following unique features: without poisoning effect and clustering problem, having comparable reaction energy barrier for low-temperature oxidation, and low cost for large-scale catalytic CO oxidation in industry.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.

ABSTRACT
Two-dimensional organometallic sheets containing regularly and separately distributed transition atoms (TMs) have received tremendous attentions due to their flexibility in synthesis, well-defined geometry and the promising applications in hydrogen storage, electronic circuits, quantum Hall effect, and spintronics. Here for the first time we present a study on the superior catalytic CO oxidation capacity of a Cr-phthalocyanine porous sheet proceeding first via Langmuir-Hinshelwood (LH) mechanism and then via Eley-Rideal (ER) mechanism. Compared to the noble metal based catalysts or graphene supported catalysts, our studied system has following unique features: without poisoning effect and clustering problem, having comparable reaction energy barrier for low-temperature oxidation, and low cost for large-scale catalytic CO oxidation in industry.

No MeSH data available.


Related in: MedlinePlus