1
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Madden E, Zwijnenburg MA. The effect of particle size on the optical and electronic properties of hydrogenated silicon nanoparticles. Phys Chem Chem Phys 2024; 26:11695-11707. [PMID: 38563473 DOI: 10.1039/d4cp00119b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
We use a combination of many-body perturbation theory and time-dependent density functional theory to study the optical and electronic properties of hydrogen terminated silicon nanoparticles. We predict that the lowest excited states of these silicon nanoparticles are excitonic in character and that the corresponding excitons are completely delocalised over the volume of the particle. The size of the excitons is predicted to increase proportionally with the particle size. Conversely, we predict that the fundamental gap, the optical gap, and the exciton binding energy increase with decreasing particle size. The exciton binding energy is predicted to counter-act the variation in the fundamental gap and hence to reduce the variation of the optical gap with particle size. The variation in the exciton binding energy itself is probably caused by a reduction in the dielectric screening with decreasing particle size. The intensity of the excited state corresponding to the optical gap and other low energy excitations are predicted to increase with decreasing particle size. We explain this increase in terms of the 'band structure' becoming smeared out in reciprocal space with decreasing particle size, increasing the 'overlap' between the occupied and unoccupied quasiparticle states and thus, the oscillator strength. Fourier transforms of the lowest excitons show that they inherit the periodicity of the frontier quasiparticle states. This, combined with the delocalisation of the exciton and the large exciton binding energy, means that the excitons in silicon nanoparticles combine aspects of Wannier-Mott, delocalisation and effect of periodicity of the underlying structure, and Frenkel, large exciton binding energy, excitons.
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Affiliation(s)
- Eimear Madden
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Martijn A Zwijnenburg
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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2
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Morpho/Opto-structural Characterizations and XRD-Assisted Estimation of Crystallite Size and Strain in MgO Nanoparticles by Applying Williamson–Hall and Size–Strain Techniques. J CLUST SCI 2022. [DOI: 10.1007/s10876-021-02144-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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3
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Lund A, Manohara GV, Song AY, Jablonka KM, Ireland CP, Cheah LA, Smit B, Garcia S, Reimer JA. Characterization of Chemisorbed Species and Active Adsorption Sites in Mg-Al Mixed Metal Oxides for High-Temperature CO 2 Capture. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2022; 34:3893-3901. [PMID: 35573112 PMCID: PMC9097159 DOI: 10.1021/acs.chemmater.1c03101] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/17/2022] [Indexed: 06/15/2023]
Abstract
Mg-Al mixed metal oxides (MMOs), derived from the decomposition of layered double hydroxides (LDHs), have been purposed as adsorbents for CO2 capture of industrial plant emissions. To aid in the design and optimization of these materials for CO2 capture at 200 °C, we have used a combination of solid-state nuclear magnetic resonance (ssNMR) and density functional theory (DFT) to characterize the CO2 gas sorption products and determine the various sorption sites in Mg-Al MMOs. A comparison of the DFT cluster calculations with the observed 13C chemical shifts of the chemisorbed products indicates that mono- and bidentate carbonates are formed at the Mg-O sites with adjacent Al substitution of an Mg atom, while the bicarbonates are formed at Mg-OH sites without adjacent Al substitution. Quantitative 13C NMR shows an increase in the relative amount of strongly basic sites, where the monodentate carbonate product is formed, with increasing Al/Mg molar ratios in the MMOs. This detailed understanding of the various basic Mg-O sites presented in MMOs and the formation of the carbonate, bidentate carbonate, and bicarbonate chemisorbed species yields new insights into the mechanism of CO2 adsorption at 200 °C, which can further aid in the design and capture capacity optimization of the materials.
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Affiliation(s)
- Alicia Lund
- Materials
Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - G. V. Manohara
- Research
Center for Carbon Solutions (RCCS), School of Engineering and Physical
Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Ah-Young Song
- Materials
Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - Kevin Maik Jablonka
- Laboratory
of Molecular Simulation (LSMO), Institut
des Sciences et Ingénierie Chimiques, École Polytechnique
Fédérale de Lausanne (EPFL), Rue de l’Industrie 17, Sion CH-1951, Switzerland
| | - Christopher P. Ireland
- Laboratory
of Molecular Simulation (LSMO), Institut
des Sciences et Ingénierie Chimiques, École Polytechnique
Fédérale de Lausanne (EPFL), Rue de l’Industrie 17, Sion CH-1951, Switzerland
| | - Li Anne Cheah
- Research
Center for Carbon Solutions (RCCS), School of Engineering and Physical
Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Berend Smit
- Laboratory
of Molecular Simulation (LSMO), Institut
des Sciences et Ingénierie Chimiques, École Polytechnique
Fédérale de Lausanne (EPFL), Rue de l’Industrie 17, Sion CH-1951, Switzerland
| | - Susana Garcia
- Research
Center for Carbon Solutions (RCCS), School of Engineering and Physical
Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Jeffrey A. Reimer
- Materials
Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
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4
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Zwijnenburg M. The Effect of Particle Size and Composition on the Optical and Electronic Properties of CdO and CdS Rocksalt Nanoparticles. Phys Chem Chem Phys 2022; 24:21954-21965. [DOI: 10.1039/d2cp01342h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quantum confinement like behaviour in CdO and CdS nanoparticles is demonstrated through explicit evGW-BSE many-body perturbation theory calculations on 0.6-1.4 nanometre particles of these materials. However, while the lowest optical...
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5
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Affiliation(s)
- Chen Hui
- Foundation Department of Yantai Vocational College, Qingdao, People’s Republic of China
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6
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Khezri B, Maskanati M, Ghanemnia N, Shabani Gokeh M, Rezaei S, Chang L. Efficient detection of thioguanine drug using boron nitride nanocage: DFT outlook of solvent effect and AIM analysis. INORG CHEM COMMUN 2021. [DOI: 10.1016/j.inoche.2021.109015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Zwijnenburg MA. The effect of particle size on the optical and electronic properties of magnesium oxide nanoparticles. Phys Chem Chem Phys 2021; 23:21579-21590. [PMID: 34553204 DOI: 10.1039/d1cp02683f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The quasiparticle states, fundamental gaps, optical gaps, exciton binding energies and UV-vis spectra for a series of cuboidal nanoparticles of the prototypical oxide magnesium oxide (MgO), the largest of which has 216 atoms and edges of 1 nm, were predicted using many-body perturbation theory (evGW-BSE). The evolution of the properties with the particle size was explicitly studied. It was found that, while the highest occupied and lowest unoccupied quasiparticle states and fundamental gap change with the particle size, the optical gap remains essentially fixed for all but the smallest nanoparticles, in line with what was previously observed experimentally. The explanation for these observations is demonstrated to be that, while the optical gap is associated with an exciton that is highly localised around the particle's corner atoms, the highest occupied and lowest unoccupied quasiparticle states, while primarily localised on the oxygen corner atoms (hole) and magnesium corner atoms (electron), show significant delocalisation along the edges. The strong localisation of the exciton associated with the optical gap on the corner atoms is argued to also explain why the nanoparticles have much smaller optical gaps and red-shifted spectra compared to bulk MgO. Finally, it is discussed how this non-quantum confinement behaviour, where the properties of the nanoparticles arise from surface defects rather than differences in localisation of quasiparticle or exciton states, appears typical of alkaline earth oxide nanoparticles, and that the true optical gap of bulk crystals of such materials is also probably the result of surface defects, even if unobservable experimentally.
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Affiliation(s)
- Martijn A Zwijnenburg
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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8
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Li B, Zhang X, Stauber JM, Miller TF, Spokoyny AM. Electronic Structure of Superoxidized Radical Cationic Dodecaborate-Based Clusters. J Phys Chem A 2021; 125:6141-6150. [PMID: 34240867 DOI: 10.1021/acs.jpca.1c03927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The expanding field of boron clusters has attracted continuous theoretical efforts to understand their diverse structures and unique bonding. We recently discovered a new reversible redox event of B12(O-3-methylbutyl)12 in which the superoxidized radical cationic form [B12(O-3-methylbutyl)12]•+ was identified and isolated for the first time. Herein, comprehensive (TD-)DFT studies in tandem with electrochemical experiments were employed to demonstrate the generality of the reported behavior across perfunctionalized B12(OR)12 clusters (R = aryl or alkyl). While the spin density of radical cationic clusters is delocalized in the core region, the oxidation brings about notable gains of positive partial charges on the supporting groups whose electronics can readily tune the redox potential of the 0/•+ couple. The underlying changes of frontier orbitals were elucidated, and the resulting [B12(OR)12]•+ species manifest a general diagnostic absorption as a consequence of mixed local/charge-transfer excitations.
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Affiliation(s)
- Bo Li
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Xinglong Zhang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Julia M Stauber
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Thomas F Miller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Alexander M Spokoyny
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
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9
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Schwab T, Aicher K, Razouq H, Zickler GA, Diwald O. Segregation Engineering in MgO Nanoparticle-Derived Ceramics: The Impact of Calcium and Barium Admixtures on the Microstructure and Light Emission Properties. ACS APPLIED MATERIALS & INTERFACES 2021; 13:25493-25502. [PMID: 34009927 PMCID: PMC8176451 DOI: 10.1021/acsami.1c02931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Nanostructured segregates of alkaline earth oxides exhibit bright photoluminescence emission and great potential as components of earth-abundant inorganic phosphors. We evaluated segregation engineering of Ca2+- and Ba2+-admixtures in sintered MgO nanocube-derived compacts. Compaction and sintering transform the nanoparticle agglomerates into ceramics with residual porosities of Φ = 24-28%. Size mismatch drives admixture segregation into the intergranular region, where they form thin metal oxide films and inclusions decorating grain boundaries and pores. An important trend in the median grain size evolution of the sintered bodies with dCa(10 at. %) = 90 nm < dBa(1 at. %) = 160 nm < dMgO = 250 nm ∼ dCa(1 at. %) = 280 nm < dBa(10 at. %) = 870 nm is rationalized by segregation and interface energies, barriers for ion diffusion, admixture concentration, and the increasing surface basicity of the grains during processing. We outline the potential of admixtures on interface engineering in MgO nanocrystal-derived ceramics and demonstrate that in the sintered compacts, the photoluminescence emission originating from the grain surfaces is retained. Interior parts of the ceramic, which are accessible to molecules from the gas phase, contribute with oxygen partial pressure-dependent intensities to light emission.
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10
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Precipitator concentration-dependent opto-structural properties of MgO nanoparticles fabricated using natural brine. SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-2645-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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11
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Aziz BK, Karim MAH. Efficient catalytic photodegradation of methylene blue from medical lab wastewater using MgO nanoparticles synthesized by direct precipitation method. REACTION KINETICS MECHANISMS AND CATALYSIS 2019. [DOI: 10.1007/s11144-019-01677-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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12
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Lemeski ET, Javan MB, Soltani A, Azmoodeh Z. Optical and Electronic Properties of Al-Doped Mg12O12 Nanocluster: A Theoretical Study. RUSS J INORG CHEM+ 2019. [DOI: 10.1134/s003602361906010x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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14
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Abstract
Knowing the possible structures of individual clusters in nanostructured materials is an important first step in their design. With previous structure prediction data for BaO nanoclusters as a basis, data mining techniques were used to investigate candidate structures for magnesium oxide, calcium oxide and strontium oxide clusters. The lowest-energy structures and analysis of some of their structural properties are presented here. Clusters that are predicted to be ideal targets for synthesis, based on being both the only thermally accessible minimum for their size, and a size that is thermally accessible with respect to neighbouring sizes, include global minima for: sizes
n
=
9
,
15
,
16
,
18
and 24 for (MgO)
n
; sizes
n
=
8
,
9
,
12
,
16
,
18
and 24 for (CaO)
n
; the greatest number of sizes of (SrO)
n
clusters (
n
=
8
,
9
,
10
,
12
,
13
,
15
,
16
,
18
and 24); and for (BaO)
n
sizes of
n
=
8
,
10
and 16.
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15
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Escher SG, Lazauskas T, Zwijnenburg MA, Woodley SM. Structure prediction of (BaO) n nanoclusters forn⩽24using an evolutionary algorithm. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Lamiel-Garcia O, Cuko A, Calatayud M, Illas F, Bromley ST. Predicting size-dependent emergence of crystallinity in nanomaterials: titania nanoclusters versus nanocrystals. NANOSCALE 2017; 9:1049-1058. [PMID: 27809322 DOI: 10.1039/c6nr05788h] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Bottom-up and top-down derived nanoparticle structures refined by accurate ab initio calculations are used to investigate the size dependent emergence of crystallinity in titania from the monomer upwards. Global optimisation and data mining are used to provide a series of (TiO2)N global minima candidates in the range N = 1-38, where our approach provides many new low energy structures for N > 10. A range of nanocrystal cuts from the anatase crystal structure are also considered up to a size of over 250 atoms. All nanocrystals considered are predicted to be metastable with respect to non-crystalline nanoclusters, which has implications with respect to the limitations of the cluster approach to modelling large titania nanosystems. Extrapolating both data sets using a generalised expansion of a top-down derived energy expression for nanoparticles, we obtain an estimate of the non-crystalline to crystalline crossover size for titania. Our results compare well with the available experimental results and imply that anatase-like crystallinity emerges in titania nanoparticles of approximately 2-3 nm diameter.
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Affiliation(s)
- Oriol Lamiel-Garcia
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Andi Cuko
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain and SorbonneUniversités, UPMC Univ Paris 06, CNRS, Laboratoire de Chimie Théorique CC 137, 4, place Jussieu F. 75252, Paris Cedex 05, France
| | - Monica Calatayud
- SorbonneUniversités, UPMC Univ Paris 06, CNRS, Laboratoire de Chimie Théorique CC 137, 4, place Jussieu F. 75252, Paris Cedex 05, France and InstitutUniversitaire de France, France
| | - Francesc Illas
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Stefan T Bromley
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain and Institució Catalana de Recerca i Estudis Avançats (ICREA), E-08010 Barcelona, Spain.
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17
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Xia Y, Li Z. Laser-assisted field evaporation of metal oxides: A time-dependent density functional theory study. J Chem Phys 2016; 145:204704. [PMID: 27908142 DOI: 10.1063/1.4968213] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To understand laser-assisted field evaporation of semiconductors and insulators at the microscopic level, we study the time evolution of the electronic and atomic structure of a MgO cluster in high electrostatic fields subjected to strong laser pulses. We find that the critical laser intensity for evaporation decreases linearly as the electrostatic field strength increases. The optical absorption enhancement in high electrostatic field is confirmed by the redshift of the optical absorption spectra, the reduction of the energy gap, and the increase of the absorption cross section.
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Affiliation(s)
- Yu Xia
- School of Physics, Sun Yat-sen University, No. 135 Xingang Xi Road, Guangzhou 510275, People's Republic of China
| | - Zhibing Li
- School of Physics, Sun Yat-sen University, No. 135 Xingang Xi Road, Guangzhou 510275, People's Republic of China
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18
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Guiglion P, Berardo E, Butchosa C, Wobbe MCC, Zwijnenburg MA. Modelling materials for solar fuel synthesis by artificial photosynthesis; predicting the optical, electronic and redox properties of photocatalysts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:074001. [PMID: 26808228 DOI: 10.1088/0953-8984/28/7/074001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this mini-review, we discuss what insight computational modelling can provide into the working of photocatalysts for solar fuel synthesis and how calculations can be used to screen for new promising materials for photocatalytic water splitting and carbon dioxide reduction. We will extensively discuss the different relevant (material) properties and the computational approaches (DFT, TD-DFT, GW/BSE) available to model them. We illustrate this with examples from the literature, focussing on polymeric and nanoparticle photocatalysts. We finish with a perspective on the outstanding conceptual and computational challenges.
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Affiliation(s)
- Pierre Guiglion
- Department of Chemistry, University College London, 20 Gordon street, London WC1H 0AJ, UK
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19
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Wobbe MCC, Zwijnenburg MA. Chemical trends in the optical properties of rocksalt nanoparticles. Phys Chem Chem Phys 2015; 17:28892-900. [PMID: 26456027 DOI: 10.1039/c5cp04851f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nature and magnitude of the optical gaps of rocksalt alkaline earth (MgO, CaO, SrO, MgS, MgSe) and transition metal chalcogenide (CdO, PbS) nanoparticles are studied using time-dependent density functional theory (TD-DFT) calculations on (MX)32 nanoparticles. We demonstrate, just as we previously showed for MgO, that TD-DFT calculations on rocksalt nanoparticles require the use of hybrid exchange-correlation (XC-)functionals with a high percentage of Hartree-Fock like exchange (e.g. BHLYP) or range-separated XC-functionals to circumvent problems related to the description of charge-transfer excitations. Concentrating on the results obtained with TD-BHLYP we show that the optical gap in rocksalt nanoparticles displays a wide range of behavior; ranging from large optical gaps stemming from a localized excitation involving corner atoms in alkaline earth oxides to a delocalized excitation and small optical gaps in the transition metal chalcogenides. Finally, we rationalize this wide range of behaviour in terms of differences in the degree to which the Coulombic interaction between the excited electron and hole is screened in the different nanoparticles, and relate it to the optical dielectric constants of the bulk materials the nanoparticles are made from.
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Affiliation(s)
- Milena C C Wobbe
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
| | - Martijn A Zwijnenburg
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
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