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Gutsev LG, Nations S, Ramachandran BR, Gutsev GL, Wang S, Aldoshin S, Duan Y. Redox Chemistry of the Subphases of α-CsPbI 2Br and β-CsPbI 2Br: Theory Reveals New Potential for Photostability. Nanomaterials (Basel) 2023; 13:276. [PMID: 36678028 PMCID: PMC9862745 DOI: 10.3390/nano13020276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 01/04/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
The logic in the design of a halide-mixed APb(I1−xBrx)3 perovskite is quite straightforward: to combine the superior photovoltaic qualities of iodine-based perovskites with the increased stability of bromine-based perovskites. However, even small amounts of Br doped into the iodine-based materials leads to some instability. In the present report, using first-principles computations, we analyzed a wide variety of α-CsPbI2Br and β-CsPbI2Br phases, compared their mixing enthalpies, explored their oxidative properties, and calculated their hole-coupled and hole-free charged Frenkel defect (CFD) formations by considering all possible channels of oxidation. Nanoinclusions of bromine-rich phases in α-CsPbI2Br were shown to destabilize the material by inducing lattice strain, making it more susceptible to oxidation. The uniformly mixed phase of α-CsPbI2Br was shown to be highly susceptible towards a phase transformation into β-CsPbI2Br when halide interstitial or halide vacancy defects were introduced into the lattice. The rotation of PbI4Br2 octahedra in α-CsPbI2Br allows it either to transform into a highly unstable apical β-CsPbI2Br, which may phase-segregate and is susceptible to CFD, or to phase-transform into equatorial β-CsPbI2Br, which is resilient against the deleterious effects of hole oxidation (energies of oxidation >0 eV) and demixing (energy of mixing <0 eV). Thus, the selective preparation of equatorial β-CsPbI2Br offers an opportunity to obtain a mixed perovskite material with enhanced photostability and an intermediate bandgap between its constituent perovskites.
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Affiliation(s)
- Lavrenty Gennady Gutsev
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA
- Federal Research Center for Problems of Chemical Physics and Medicinal Chemistry of RAS, Semenov Prospect 1, Chernogolovka 142432, Russia
| | - Sean Nations
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA
| | | | | | - Shengnian Wang
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA
| | - Sergei Aldoshin
- Federal Research Center for Problems of Chemical Physics and Medicinal Chemistry of RAS, Semenov Prospect 1, Chernogolovka 142432, Russia
| | - Yuhua Duan
- National Energy Technology Laboratory, United States Department of Energy, Pittsburgh, PA 15236, USA
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Gutsev GL, López Peña HA, McPherson SL, Boateng DA, Ramachandran BR, Gutsev LG, Tibbetts KM. From Neutral Aniline to Aniline Trication: A Computational and Experimental Study. J Phys Chem A 2020; 124:3120-3134. [PMID: 32233368 DOI: 10.1021/acs.jpca.0c00686] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report density functional theory computations and photoionization mass spectrometry measurements of aniline and its positively charged ions. The geometrical structures and properties of the neutral and singly, doubly, and triply positively charged aniline are computed using density functional theory with the generalized gradient approximation. At each charge, there are multiple isomers closely spaced in total energy. Whereas the lowest energy states of both neutral and cation have the same topology C6H5-NH2, the dication and trication have the C5NH5-CH2 topology with the nitrogen atom in the meta- and para-positions, respectively. We compute the dissociation pathways of all four charge states to NH or NH+ and NH2 or NH2+, depending on the initial charge of the aniline precursor. Dissociation leading to the formation of NH (from the neutral and cation) and NH+ (from the dication and trication) proceeds through multiple transition states. On the contrary, the dissociation of NH2 (from the neutral and cation) and NH2+ (from the dication and trication) is found to proceed without an activation energy barrier. The trication was found to be stable toward abstraction on NH+ and NH2+ by 0.96 and 0.18 eV, respectively, whereas the proton affinity of the trication is substantially higher, 1.98 eV. The mass spectra of aniline were recorded with 1300 nm, 20 fs pulses over the peak intensity range of 1 × 1013 to 3 × 1014 W cm-2. The analysis of the mass spectra suggests high stability of both dication and trication to fragmentation. The formation of the fragment NH+ and NH2+ ions is found to proceed via Coulomb explosion.
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Affiliation(s)
- G L Gutsev
- Department of Physics, Florida A&M University, Tallahassee, Florida 32307, United States
| | - H A López Peña
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - S L McPherson
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - D Ampadu Boateng
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - B R Ramachandran
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272, United States
| | - L G Gutsev
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272, United States.,Institute of Problems of Chemical Physics of Russian Academy of Sciences, Chernogolovka, Moscow District 142432, Russia
| | - K M Tibbetts
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Gutsev GL, Bozhenko KV, Gutsev LG, Utenyshev AN, Aldoshin SM. Hydrogenation of 3d-metal oxide clusters: Effects on the structure and magnetic properties. J Comput Chem 2019; 40:562-571. [PMID: 30549078 DOI: 10.1002/jcc.25739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 11/08/2022]
Abstract
The geometrical structures and properties of the M8 O12 , M8 O12 H8 , and M8 O12 H12 clusters are explored using density functional theory with the generalized gradient approximation for all 3d-metals M from Sc to Zn. It is found that the geometries and total spin magnetic moments of the clusters depended strongly on the 3d-atom type and the hydrogenation extent. More than the half of all of the 30 clusters had singlet lowest total energy states, which could be described as either nonmagnetic or antiferromagnetic. Hydrogenation increases the total spin magnetic moments of the M8 O12 H12 clusters when MMnNi, which become larger by four Bohr magneton than those of the corresponding unary clusters M8 . Hydrogenation substantially affects such properties as polarizability, forbidden band gaps, and dipole moments. Collective superexchange where the local total spin magnetic moments of two atom squads are coupled antiparallel was observed in antiferromagnetic singlet states of Fe8 O12 H8 and Co8 O12 H8 , whereas the lowest total energy states of their neighbors Mn8 O12 H8 and Ni8 O12 H8 are ferrimagnetic and ferromagnetic, respectively. Hydrogenation leads to a decrease in the average binding energy per atom when moving across the 3d-metal atom series. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- G L Gutsev
- Department of Physics, Florida A&M University, Tallahassee, Florida, 32307
| | - K V Bozhenko
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Moscow Region, Russia.,Рeoples' Friendship University of Russia (RUDN University), Moscow 117198, Russian Federation
| | - L G Gutsev
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia, 23284
| | - A N Utenyshev
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Moscow Region, Russia
| | - S M Aldoshin
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Moscow Region, Russia
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Gutsev LG, Gutsev GL, Jena P. Collective Superexchange and Exchange Coupling Constants in the Hydrogenated Iron Oxide Particle Fe 8O 12H 8. J Phys Chem A 2018; 122:5043-5049. [PMID: 29746132 DOI: 10.1021/acs.jpca.8b03034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Motivated by the fact that Fe2O3 nanoparticles are used in the treatment of cancer, we have examined the role of ligands on the magnetic properties of these particles by focusing on (Fe2O3)4 as a prototype system with H as ligands. Using the Broken-Symmetry Density Functional Theory, we observed a strong collective superexchange in the hydrogenated Fe8O12H8 cluster. The average antiferromagnetic exchange coupling constant between the four iron-iron oxo-bridged pairs was found to be -178 cm-1, whereas coupling constants between hydroxo-bridged pairs were much smaller. We found that despite the apparent symmetry of the iron atom framework, it is not reasonable to assume this symmetry when fitting the exchange coupling constants. We also analyzed the geometrical and magnetic properties of Fe8O12H n for n = 0-12 and found that hydrogenating oxo-bridges would generally inhibit the Fe-O-Fe antiferromagnetic superexchange interactions. Antiferromagnetic lowest total energy states become favorable only when specific distributions of hydrogen atoms are realized. The (HO)4-Fe4(all spin-up)-O4-Fe4(all spin-down)-(OH)4 configuration in Fe8O12H8 presents such an example. This symmetric configuration can be considered a superdiatomic system.
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Affiliation(s)
- L G Gutsev
- Department of Physics , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - G L Gutsev
- Department of Physics , Florida A&M University , Tallahassee , Florida 32307 , United States
| | - P Jena
- Department of Physics , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
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