Atomic under-coordination fascinated catalytic and magnetic behavior of Pt and Rh nanoclusters

Ahmadi, Samad; Zhang, Xi; Gong, Yinyan; Sun, Chang Q.

doi:10.1039/c4cp02499k

Cited by 6 publications

(6 citation statements)

References 97 publications

(174 reference statements)

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“…349 Table 18 summarizes the estimated information from the size trend of XPS. Outcomes show consistently the size induced quantum entrapment to the electron BE without any exception albeit the accuracy of derivatives, as further confirmed with DFT calculations for the Rh and Pt clusters 350 and Cu and Ag clusters. 351 …”

Section: Bols−tb Formulation and Quantificationsupporting

confidence: 75%

Coordination-Resolved Electron Spectrometrics

et al. 2015

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Section: Bols−tb Formulation and Quantificationsupporting

confidence: 75%

Coordination-Resolved Electron Spectrometrics

et al. 2015

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“…Moreover, for Ag, Cu, Pt, and Rh COh55 nanoclusters at negative excess charge state (-1) the shell charge change is equal to -2.098, -2.274, -1.743, and -2.825 e in the outermost shell, and 1.032 e, 1.188 e, 0.594 e, and 1.605 e in the interior shell.Consequently, other COh and M-Dh nanoclusters with neutral and negative excess charge states follow the same trend for different sizes and structures. Therefore, the charge transfer was observed for the neutral and negative excess charge states of MN metallic nanoclusters, which is consistent with previous theoretical calculations and experimental observations 115,158,[208][209][210].…”

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confidence: 90%

Quantum entrapment and valence charge polarization in Ag, Cu, Pt, and Rh nanoclusters

Ahmadi¹

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Atomic under-coordination and non-bonding electrons are extensively used in nanomaterials and nanostructures. The bonds between the under-coordinated sites follow the rule of relaxation dynamics, although quantum confinement (QC) theory, Coulomb blockade, and size-dependent dynamic effects cannot describe the change in Hamiltonian and other magnitudes. The effect of under-coordinated atom on the electronic structures of nanomaterials was calculated in this study using the bond-orderlength-strength (BOLS) correlation and non-bonding electron polarization (NEP) notations. The Hamiltonian perturbation of the atomic under-coordination entrapped the core electrons and polarized the valence charge. Consistency between the BOLS-NEP notation and density functional theory (DFT) calculations on Ag, Cu, Pt, and Rh nanoclusters with cuboctahedral (COh) and Marks decahedral (M-Dh) structures confirmed that the shorter and stronger bonds between atomic under-coordination induced local densification, quantum entrapment, and valence charge polarization. The strong localization determined the intriguing catalytic, magnetic, and plasmonic attributes of these metallic nanoclusters. The effect of excess charge states from (+2) to (-2) was determined using DFT calculations and BOLS correlation theories on the metallic nanoclusters with COh and M-Dh structures. Consistency between DFT calculations and experimental observations confirmed our BOLS predictions including the local bond length relaxation, charge investigated using excess charge states, including negative, neutral, and positive charges Chapter 1: Introduction 3 on the surface in both theoretical and experimental observations. 25-27 The excess charge states on the nanocluster surface play a significant role in the ability of catalysts in adjusting oxide support. Bond-order-length-strength (BOLS) correlation 28 has been used to refine the nonbonding electron polarization (NEP) theory, 3, 29, 30 to solve associated problems, 31, 32 including superfluidity in carbon nanotube channels, 33 superlubricity in dry sliding, 31, 34 and supersolidity of 4 He with superelasticity and superfluidity. 35 The effect of undercoordinated atoms and excess charge states on Ag, Cu, Pt, and Rh metallic nanoclusters are investigated in this study according to the BOLS-NEP theory. According to unique properties of these metallic nanoclusters such as magnetic and nonmagnetic order, and plasmon and catalyst applications, we are chosen Ag, Cu, Pt, and Rh metallic nanoclusters in this thesis. In addition, the results of Ag, Cu, Pt, and Rh metallic nanoclusters are presented separately, in Chapters 4 and 5, respectively, because Ag, Cu, Pt, and Rh belong to different elements such as Nobel and open metals. 1.2 Challenges The concept of broken bonds and non-bonding in nanomaterials is complicated. According to theoretical and experimental observations, valence band polarization, CLS, lattice strain, charge transfer, magnetization, optical application, and electronic properties of metallic nanoclusters ar...

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“…In the BOLS convention [15,[51][52][53][54], we choose the first and third atoms of K 44 cluster for the standard reference CN(z) for the atoms at sites of first and second atomic layers and combing the BOLS convention, we can estimated z 1 = 2.67 and z 2 = 5.12. From the relation of C(z i ) in Eq.…”

Section: N-dependence Of Nanoclustersmentioning

confidence: 99%

Coordination-resolved local bond strain and 3p energy entrapment of K atomic clusters and K(1 1 0) skin

Zhang

Guo

et al. 2015

Applied Surface Science

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Keywords:K nanoclusters and solid skin XPS DFT BOLS Energy entrapment a b s t r a c tWe have examined the atomic coordination effect on the local bond strain and the 3p core-level shift of K(1 1 0) skin and nanoclusters using a combination of the bond order-length-strength correlation notion, tight-binding approach, density functional theory calculations, and photoelectron spectroscopy measurements. It turns out that: (i) the 3p core-level shifts from 15.595 ± 0.003 eV for an isolated K atom by 2.758 eV to the bulk value of 18.353 eV; (ii) the effective atomic coordination number reduces from the bulk value of 12 to 3.93 for the first layer and to 5.81 for the second layer of K(1 1 0) skin associated with the local lattice strain of 12.76%, a binding energy density 72.67%, and atomic cohesive energy −62.46% for the skin; and (iii) K cluster size reduction lowers the effective atomic coordination number and enhances further the skin electronic attribution. Results have revealed that the 3p core-level shifts of K(1 1 0) and nanoclusters originate from perturbation of the Hamiltonian by under-coordination induced charge densification and quantum entrapment.

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Atomic under-coordination fascinated catalytic and magnetic behavior of Pt and Rh nanoclusters

Cited by 6 publications

References 97 publications

Coordination-Resolved Electron Spectrometrics

Coordination-Resolved Electron Spectrometrics

Quantum entrapment and valence charge polarization in Ag, Cu, Pt, and Rh nanoclusters

Coordination-resolved local bond strain and 3p energy entrapment of K atomic clusters and K(1 1 0) skin

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