### Abstract

The energetic properties of Ag_{n} clusters in ZSM-5 zeolite were investigated using density functional theory (DFT) calculations with the B3PW91 functional. Several optimized geometries (Ag_{n}-ZSM-5(Al_{m}), 3 ≤ n ≤ 6 and 1 ≤ m ≤ 5) were obtained using this method, where m is the number of Al atoms substituted for Si atoms of a ten-membered ring of ZSM-5. DFT calculations found that an Ag_{n} cluster is well stabilized within a ZSM-5(Al_{m}) cavity at n = m + 2. The stabilization conditions can be explained by frontier orbital theory because the HOMO of Ag_{m+2}-ZSM-5(Al_{m}) zeolites is composed by totally symmetric 5s-based orbitals on silver atoms. The totally symmetric 5s-based orbital corresponds to a superatom S-orbital in cluster chemistry. Accordingly, the Ag_{m+2}-ZSM-5(Al_{m}) zeolites have an S^{2} electronic configuration, being similar to magic-number silver clusters in the gas phase. Time-dependent DFT calculations found significant oscillator strength at the electronic transition between 5s-based orbitals from the totally symmetric orbital (S-orbital) to that with one node (P-orbital). The S → P electronic transitions in Ag_{m+2}-ZSM-5(Al_{m}) follow the selection rule of electronic transitions of bare clusters. Because the excitation energies (λ_{max}) change with an increase in the number of contained silver atoms, the S → P electronic transitions of Ag_{m+2}-ZSM-5(Al_{m}) could be used to identify the state of the inner silver atoms.

Original language | English |
---|---|

Pages (from-to) | 4950-4959 |

Number of pages | 10 |

Journal | RSC Advances |

Volume | 7 |

Issue number | 9 |

DOIs | |

Publication status | Published - 2017 |

### Fingerprint

### ASJC Scopus subject areas

- Chemistry(all)
- Chemical Engineering(all)

### Cite this

*RSC Advances*,

*7*(9), 4950-4959. https://doi.org/10.1039/c6ra26492a

**Utilizing super-atom orbital ideas to understand properties of silver clusters inside ZSM-5 zeolite.** / Yumura, Takashi; Kumondai, Mitsuhiro; Kuroda, Yasushige; Wakasugi, Takashi; Kobayashi, Hisayoshi.

Research output: Contribution to journal › Article

*RSC Advances*, vol. 7, no. 9, pp. 4950-4959. https://doi.org/10.1039/c6ra26492a

}

TY - JOUR

T1 - Utilizing super-atom orbital ideas to understand properties of silver clusters inside ZSM-5 zeolite

AU - Yumura, Takashi

AU - Kumondai, Mitsuhiro

AU - Kuroda, Yasushige

AU - Wakasugi, Takashi

AU - Kobayashi, Hisayoshi

PY - 2017

Y1 - 2017

N2 - The energetic properties of Agn clusters in ZSM-5 zeolite were investigated using density functional theory (DFT) calculations with the B3PW91 functional. Several optimized geometries (Agn-ZSM-5(Alm), 3 ≤ n ≤ 6 and 1 ≤ m ≤ 5) were obtained using this method, where m is the number of Al atoms substituted for Si atoms of a ten-membered ring of ZSM-5. DFT calculations found that an Agn cluster is well stabilized within a ZSM-5(Alm) cavity at n = m + 2. The stabilization conditions can be explained by frontier orbital theory because the HOMO of Agm+2-ZSM-5(Alm) zeolites is composed by totally symmetric 5s-based orbitals on silver atoms. The totally symmetric 5s-based orbital corresponds to a superatom S-orbital in cluster chemistry. Accordingly, the Agm+2-ZSM-5(Alm) zeolites have an S2 electronic configuration, being similar to magic-number silver clusters in the gas phase. Time-dependent DFT calculations found significant oscillator strength at the electronic transition between 5s-based orbitals from the totally symmetric orbital (S-orbital) to that with one node (P-orbital). The S → P electronic transitions in Agm+2-ZSM-5(Alm) follow the selection rule of electronic transitions of bare clusters. Because the excitation energies (λmax) change with an increase in the number of contained silver atoms, the S → P electronic transitions of Agm+2-ZSM-5(Alm) could be used to identify the state of the inner silver atoms.

AB - The energetic properties of Agn clusters in ZSM-5 zeolite were investigated using density functional theory (DFT) calculations with the B3PW91 functional. Several optimized geometries (Agn-ZSM-5(Alm), 3 ≤ n ≤ 6 and 1 ≤ m ≤ 5) were obtained using this method, where m is the number of Al atoms substituted for Si atoms of a ten-membered ring of ZSM-5. DFT calculations found that an Agn cluster is well stabilized within a ZSM-5(Alm) cavity at n = m + 2. The stabilization conditions can be explained by frontier orbital theory because the HOMO of Agm+2-ZSM-5(Alm) zeolites is composed by totally symmetric 5s-based orbitals on silver atoms. The totally symmetric 5s-based orbital corresponds to a superatom S-orbital in cluster chemistry. Accordingly, the Agm+2-ZSM-5(Alm) zeolites have an S2 electronic configuration, being similar to magic-number silver clusters in the gas phase. Time-dependent DFT calculations found significant oscillator strength at the electronic transition between 5s-based orbitals from the totally symmetric orbital (S-orbital) to that with one node (P-orbital). The S → P electronic transitions in Agm+2-ZSM-5(Alm) follow the selection rule of electronic transitions of bare clusters. Because the excitation energies (λmax) change with an increase in the number of contained silver atoms, the S → P electronic transitions of Agm+2-ZSM-5(Alm) could be used to identify the state of the inner silver atoms.

UR - http://www.scopus.com/inward/record.url?scp=85010441788&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85010441788&partnerID=8YFLogxK

U2 - 10.1039/c6ra26492a

DO - 10.1039/c6ra26492a

M3 - Article

AN - SCOPUS:85010441788

VL - 7

SP - 4950

EP - 4959

JO - RSC Advances

JF - RSC Advances

SN - 2046-2069

IS - 9

ER -