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Sengupta T, Khanna SN. Converting CO 2 to formic acid by tuning quantum states in metal chalcogenide clusters. Commun Chem 2023; 6:53. [PMID: 36941466 PMCID: PMC10027883 DOI: 10.1038/s42004-023-00851-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/07/2023] [Indexed: 03/23/2023] Open
Abstract
The catalytic conversion of CO2 into valuable chemicals is an effective strategy for reducing its adverse impact on the environment. In this work, the formation of formic acid via CO2 hydrogenation on bare and ligated Ti6Se8 clusters is investigated with gradient-corrected density functional theory. It is shown that attaching suitable ligands (i.e., PMe3, CO) to a metal-chalcogenide cluster transforms it into an effective donor/acceptor enabling it to serve as an efficient catalyst. Furthermore, by controlling the ratio of the attached donor/acceptor ligands, it is possible to predictably alter the barrier heights of the CO2 hydrogenation reaction and, thereby, the rate of CO2 conversion. Our calculation further reveals that by using this strategy, the barrier heights of CO2 hydrogenation can be reduced to ~0.12 eV or possibly even lower, providing unique opportunities to control the reaction rates by using different combinations of donor/acceptor ligands.
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Affiliation(s)
- Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
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2
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Ward AFM, Reber AC, Khanna SN. Periodic Trends in the Infrared and Optical Absorption Spectra of Metal Chalcogenide Clusters. J Phys Chem A 2023; 127:38-45. [PMID: 36548146 DOI: 10.1021/acs.jpca.2c05955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We have investigated the optical absorption, infrared spectra, binding energies, and other cluster properties to investigate whether periodic trends can be observed in the electronic structure of transition metal chalcogenide clusters ligated with CO ligands. Our studies demonstrate the existence of several periodic trends in the properties of pure and mixed octahedral metal chalcogenide clusters, TM6Se8(CO)6 (TM = W-Pt). We find that octahedral metal chalcogenide clusters with 96, 100, and 114 valence electrons have larger excitation energies, consistent with these clusters having closed electronic shells. Periodic trends were observed in the infrared spectra, with the CO bond stretch having the highest energy at 100 and 114 valence electrons due to the closed electronic shell minimizing back-bonding with the CO molecule. A periodic trend in the antisymmetric TM-C stretch was also observed, with the vibrational energy increasing as the valence electron count increased. This is due to decrease in the TM-C bond length, resulting in a larger force constant. These results reveal that periodic trends seen earlier in simple or noble-metal clusters can be observed in symmetric transition metal chalcogenide clusters, showing that the superatom concept in metal chalcogenide clusters goes beyond electronic excitations, and can be seen in other observable properties.
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Affiliation(s)
- Alain F M Ward
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia23284-2000, United States
| | - Arthur C Reber
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia23284-2000, United States
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia23284-2000, United States
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Reber AC, Sengupta T, Bista D, Khanna SN. Magic Numbers in Octahedral Ligated Metal-Chalcogenide Superatoms. Inorg Chem 2022; 61:16003-16008. [PMID: 36149274 DOI: 10.1021/acs.inorgchem.2c02361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The attainment of the superatomic state offers a unifying framework for the periodic classification of atomic clusters. Metallic clusters attain the superatomic state via the confined nearly free electron gas model that leads to groupings of quantum states marked by radial and angular momentum quantum numbers. We examine ligated octahedral metal-chalcogenide clusters where the nearly free electron gas model is invalid; however, the high symmetry can also lead to the bunching of electronic states. For octahedral TM6E8L6 clusters (TM = transition metal; E = chalcogen; L = ligand), the electronic shells are filled for valence electron counts of 96, 100, and 114 electrons. These magic electron counts are marked by large highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps, high ionization energies, and low electron affinity─all classic signatures of the superatomic state. We also find that clusters with electron counts differing from the magic counts show periodic patterns reminiscent of those observed in the periodic table of elements.
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Affiliation(s)
- Arthur C Reber
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Dinesh Bista
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
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Sengupta T, Khanna SN. Rational Design of Bimetallic Metal Chalcogenide Clusters for CO 2 Dissociation. J Phys Chem A 2022; 126:5702-5710. [PMID: 35973159 DOI: 10.1021/acs.jpca.2c03560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermochemical dissociation of CO2 on pure, ligated, and mixed transition metal (W, Cu) chalcogenide clusters are investigated using the first-principles gradient-corrected density functional approach. It is shown that although the pure and ligated metal chalcogenide clusters exhibit significantly high barriers for CO2 dissociation, the computed barriers for the mixed clusters are relatively lower. The lowest barrier is obtained for the Cu3W3Se8 cluster, which shows a dramatically reduced barrier height of only 0.41 eV. Detailed analysis reveals that the substitution of W by Cu sites leads to a charge transfer from Cu to W sites, resulting in locally active W sites. The lowering of the CO2 dissociation barriers can be attributed to the facile transfer of charge from the locally active W sites and also due to the alteration of the binding energy of CO2 to the charged W sites. Our studies provide an alternate strategy to design novel thermochemical catalysts for CO2 adsorption and subsequent dissociation.
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Affiliation(s)
- Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
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Touchton AJ, Wu G, Hayton TW. [Ni 30S 16(PEt 3) 11]: An Open-shell Nickel Sulfide Nanocluster with a “Metal-like” Core. Chem Sci 2022; 13:5171-5175. [PMID: 35655571 PMCID: PMC9093199 DOI: 10.1039/d2sc00960a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/08/2022] [Indexed: 11/21/2022] Open
Abstract
Reaction of [Ni(1,5-cod)2] (30 equiv.) with PEt3 (46 equiv.) and S8 (1.9 equiv.) in toluene, followed by heating at 115 °C for 16 h, results in the formation of the atomically precise nanocluster (APNC), [Ni30S16(PEt3)11] (1), in 14% isolated yield. Complex 1 represents the largest open-shell Ni APNC yet isolated. In the solid state, 1 features a compact “metal-like” core indicative of a high degree of Ni–Ni bonding. Additionally, SQUID magnetometry suggests that 1 possesses a manifold of closely-spaced electronic states near the HOMO–LUMO gap. In situ monitoring by ESI-MS and 31P{1H} NMR spectroscopy reveal that 1 forms via the intermediacy of smaller APNCs, including [Ni8S5(PEt3)7] and [Ni26S14(PEt3)10] (2). The latter APNC was also characterized by X-ray crystallography and features a nearly identical core structure to that found in 1. This work demonstrates that large APNCs with a high degree of metal–metal bonding are isolable for nickel, and not just the noble metals. The atomically-precise nanocluster, [Ni30S16(PEt3)11], features a compact “metal-like” core indicative of a high degree of Ni–Ni bonding, along with an open-shell ground state.![]()
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Affiliation(s)
- Alexander J Touchton
- Department of Chemistry and Biochemistry, University of California Santa Barbara California 93106 USA
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California Santa Barbara California 93106 USA
| | - Trevor W Hayton
- Department of Chemistry and Biochemistry, University of California Santa Barbara California 93106 USA
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Bista D, Sengupta T, Reber AC, Khanna SN. Interfacial magnetism in a fused superatomic cluster [Co 6Se 8(PEt 3) 5] 2. NANOSCALE 2021; 13:15763-15769. [PMID: 34528648 DOI: 10.1039/d1nr00876e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
An isolated Co6Se8(PEt3)6 cluster is non-magnetic; however, we find that a magnetic unit can be formed by fusing two Co6Se8(PEt3)5 superatoms into a [Co6Se8(PEt3)5]2 dimer. Theoretical studies indicate that the dumbbell-shaped [Co6Se8(PEt3)5]2 dimer has a spin moment of 2μB, and the spin density is primarily localized at the interfacial Co-sites where two clusters are fused into a dimer. The dimer has a low ionization energy of 4.17 eV, allowing the dimer to donate charge to C70 during the formation of a cluster assembled material, as seen in recent experiments by Nuckolls and co-workers. The donation of charge causes the dimer's magnetic moment to drop from 2μB to 1μB. We hypothesize that adding electrons to the dimer, such as doping impurities to the crystal lattice, may enhance the magnetic moment by neutralizing the charged cluster. This reveals a strategy for stabilizing magnetic moments in ligated cluster assemblies.
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Affiliation(s)
- Dinesh Bista
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
| | - Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
| | - Arthur C Reber
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284-2000, USA.
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Khanna SN, Reber AC, Bista D, Sengupta T, Lambert R. The superatomic state beyond conventional magic numbers: Ligated metal chalcogenide superatoms. J Chem Phys 2021; 155:120901. [PMID: 34598575 DOI: 10.1063/5.0062582] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The field of cluster science is drawing increasing attention due to the strong size and composition-dependent properties of clusters and the exciting prospect of clusters serving as the building blocks for materials with tailored properties. However, identifying a unifying central paradigm that provides a framework for classifying and understanding the diverse behaviors is an outstanding challenge. One such central paradigm is the superatom concept that was developed for metallic and ligand-protected metallic clusters. The periodic electronic and geometric closed shells in clusters result in their properties being based on the stability they gain when they achieve closed shells. This stabilization results in the clusters having a well-defined valence, allowing them to be classified as superatoms-thus extending the Periodic Table to a third dimension. This Perspective focuses on extending the superatomic concept to ligated metal-chalcogen clusters that have recently been synthesized in solutions and form assemblies with counterions that have wide-ranging applications. Here, we illustrate that the periodic patterns emerge in the electronic structure of ligated metal-chalcogenide clusters. The stabilization gained by the closing of their electronic shells allows for the prediction of their redox properties. Further investigations reveal how the selection of ligands may control the redox properties of the superatoms. These ligated clusters may serve as chemical dopants for two-dimensional semiconductors to control their transport characteristics. Superatomic molecules of multiple metal-chalcogen superatoms allow for the formation of nano-p-n junctions ideal for directed transport and photon harvesting. This Perspective outlines future developments, including the synthesis of magnetic superatoms.
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Affiliation(s)
- Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
| | - Arthur C Reber
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
| | - Dinesh Bista
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
| | - Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
| | - Ryan Lambert
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
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Bista D, Sengupta T, Reber AC, Khanna SN. A Magnetic Superatomic Dimer with an Intense Internal Electric Dipole Moment. J Phys Chem A 2021; 125:816-824. [DOI: 10.1021/acs.jpca.0c10262] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dinesh Bista
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Arthur C. Reber
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Shiv N. Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
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Bista D, Chauhan V, Sengupta T, Reber AC, Khanna SN. A ligand-induced homojunction between aluminum-based superatomic clusters. NANOSCALE 2020; 12:12046-12056. [PMID: 32469025 DOI: 10.1039/d0nr02611e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A superatomic molecule formed by joining two metallic clusters linked by an organometallic bridge can behave like a semiconductor and the addition of ligands can induce a significant energy level shift across an inter-cluster homojunction. This shift is induced by the N-ethyl-2-pyrrolidone ligands, and the placement of the ligands strongly affects the direction of the dipole moment, including the case where the dipole moment is parallel to the cluster interface. This computational study provides an alternative strategy for constructing nanometer-scale electronic interfaces between clusters mimicking semiconductor motifs. The semiconducting features in the PAl12 clusters emerge from the grouping of the quantum states in a confined nearly free electron gas that creates a substantial energy gap. An organometallic Ge(CH3)2(CH2)2 bridge links the clusters while maintaining the cluster's electronic shell structure. The amount of level shifting between the bridged clusters can be changed by controlling the number of ligands. Attaching multiple ligands can result in a broken gap energy alignment in which the HOMO level of one cluster is aligned with the LUMO level of the other bridged cluster. Furthermore, the singly ligated bridged superatomic molecule is found to exhibit promising features to separate the electron-hole pairs for photovoltaic applications.
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Affiliation(s)
- Dinesh Bista
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000, USA.
| | - Vikas Chauhan
- Ramjas College, University of Delhi, Delhi-110007, India
| | - Turbasu Sengupta
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000, USA.
| | - Arthur C Reber
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000, USA.
| | - Shiv N Khanna
- Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000, USA.
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Prabha S, Reber AC, Khanna SN. The structure and stability of CrnTem (1 ≤ n ≤ 6, 1 ≤ m ≤ 8) clusters. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mojica-Sánchez JP, Flores-Moreno R, Pineda-Urbina K, Gómez-Sandoval Z. Exploring the Structure, Energetic, and Magnetic Properties of Neutral Small Lithium Clusters Doped with Yttrium: Supermagnetic Atom Research. ACS OMEGA 2018; 3:11252-11261. [PMID: 31459233 PMCID: PMC6645110 DOI: 10.1021/acsomega.8b01463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/04/2018] [Indexed: 06/10/2023]
Abstract
Density functional theory calculations based on magnetic and energetic stability criteria were performed to study a series of yttrium-doped lithium neutral clusters. A relativistic approximation was employed to properly describe the energy and multiplicity of the given clusters' fundamental states. The interaction of the 4d-Y atomic orbitals with the sp-Li states had an important role in the magnetic and energetic behavior of the selected systems. The spin density was concentrated over the yttrium atom regardless of the size of the cluster. Li7Y is a new stable superatom due to its enhanced magnetic properties.
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Affiliation(s)
- Juan Pablo Mojica-Sánchez
- Facultad
de Ciencias Químicas, Universidad
de Colima, Carretera Colima-Coquimatlán km 9, Coquimatlán, Colima Col. C.P. 28400, México
| | - Roberto Flores-Moreno
- Departamento
de Química, Grupo de Estructura de la Materia, Universidad Guadalajara, Blvd. Marcelino García Barragán 1421, Guadalajara, Jalisco C.P. 44430, México
| | - Kayim Pineda-Urbina
- Facultad
de Ciencias Químicas, Universidad
de Colima, Carretera Colima-Coquimatlán km 9, Coquimatlán, Colima Col. C.P. 28400, México
| | - Zeferino Gómez-Sandoval
- Facultad
de Ciencias Químicas, Universidad
de Colima, Carretera Colima-Coquimatlán km 9, Coquimatlán, Colima Col. C.P. 28400, México
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Biltek SR, Reber AC, Khanna SN, Sen A. Complete Ag4M2(DMSA)4 (M = Ni, Pd, Pt, DMSA = Dimercaptosuccinic Acid) Cluster Series: Optical Properties, Stability, and Structural Characterization. J Phys Chem A 2017; 121:5324-5331. [DOI: 10.1021/acs.jpca.7b04669] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Scott R. Biltek
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Arthur C. Reber
- Department
of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Shiv N. Khanna
- Department
of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Ayusman Sen
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Chauhan V, Reber AC, Khanna SN. CO ligands stabilize metal chalcogenide Co6Se8(CO)n clusters via demagnetization. Phys Chem Chem Phys 2017; 19:31940-31948. [DOI: 10.1039/c7cp07606a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The role of carbon monoxide ligands on the magnetic moment of Co6Se8(CO)n clusters, n = 0–6 was investigated to better understand the interplay between the electronic structure of metal chalcogenide clusters and their ligands.
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Affiliation(s)
- Vikas Chauhan
- Department of Physics
- Virginia Commonwealth University
- Richmond
- USA
| | - Arthur C. Reber
- Department of Physics
- Virginia Commonwealth University
- Richmond
- USA
| | - Shiv N. Khanna
- Department of Physics
- Virginia Commonwealth University
- Richmond
- USA
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