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Title: Giant onsite electronic entropy enhances the performance of ceria for water splitting

Authors:
; ORCiD logo; ORCiD logo; ORCiD logo; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1400078
Report Number(s):
LLNL-JRNL-728880
Journal ID: ISSN 2041-1723
DOE Contract Number:
AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Communications; Journal Volume: 8; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY

Citation Formats

Naghavi, S. Shahab, Emery, Antoine A., Hansen, Heine A., Zhou, Fei, Ozolins, Vidvuds, and Wolverton, Chris. Giant onsite electronic entropy enhances the performance of ceria for water splitting. United States: N. p., 2017. Web. doi:10.1038/s41467-017-00381-2.
Naghavi, S. Shahab, Emery, Antoine A., Hansen, Heine A., Zhou, Fei, Ozolins, Vidvuds, & Wolverton, Chris. Giant onsite electronic entropy enhances the performance of ceria for water splitting. United States. doi:10.1038/s41467-017-00381-2.
Naghavi, S. Shahab, Emery, Antoine A., Hansen, Heine A., Zhou, Fei, Ozolins, Vidvuds, and Wolverton, Chris. Fri . "Giant onsite electronic entropy enhances the performance of ceria for water splitting". United States. doi:10.1038/s41467-017-00381-2. https://www.osti.gov/servlets/purl/1400078.
@article{osti_1400078,
title = {Giant onsite electronic entropy enhances the performance of ceria for water splitting},
author = {Naghavi, S. Shahab and Emery, Antoine A. and Hansen, Heine A. and Zhou, Fei and Ozolins, Vidvuds and Wolverton, Chris},
abstractNote = {},
doi = {10.1038/s41467-017-00381-2},
journal = {Nature Communications},
number = 1,
volume = 8,
place = {United States},
year = {Fri Aug 18 00:00:00 EDT 2017},
month = {Fri Aug 18 00:00:00 EDT 2017}
}
  • Previous studies have shown that a large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical water splitting cycles. In this context, the configurational entropy arising from oxygen off-stoichiometry in the oxide, has been the focus of most previous work. Here we report a different source of entropy, the onsite electronic configurational entropy, arising from coupling between orbital and spin angular momenta in lanthanide f orbitals. We find that onsite electronic configurational entropy is sizable in all lanthanides, and reaches a maximum value of ≈4.7 k B per oxygen vacancy for Cemore » 4+/Ce 3+ reduction. This unique and large positive entropy source in ceria explains its excellent performance for high-temperature catalytic redox reactions such as water splitting. Our calculations also show that terbium dioxide has a high electronic entropy and thus could also be a potential candidate for solar thermochemical reactions.« less
  • One key factor that limits the predictive power of molecular dynamics simulations is the accuracy and transferability of the input force field. Force fields are challenged by heterogeneous environments, where electronic responses give rise to biologically important forces such as many-body polarisation and dispersion. The importance of polarisation in the condensed phase was recognised early on, as described by Cochran in 1959 [Philosophical Magazine 4 (1959) 1082–1086] [32]. Currently in molecular simulation, dispersion forces are treated at the two-body level and in the dipole limit, although the importance of three-body terms in the condensed phase was demonstrated by Barker inmore » the 1980s [Phys. Rev. Lett. 57 (1986) 230–233] [72]. One approach for treating both polarisation and dispersion on an equal basis is to coarse grain the electrons surrounding a molecular moiety to a single quantum harmonic oscillator (cf. Hirschfelder, Curtiss and Bird 1954 [The Molecular Theory of Gases and Liquids (1954)] [37]). The approach, when solved in strong coupling beyond the dipole limit, gives a description of long-range forces that includes two- and many-body terms to all orders. In the last decade, the tools necessary to implement the strong coupling limit have been developed, culminating in a transferable model of water with excellent predictive power across the phase diagram. Transferability arises since the environment automatically identifies the important long range interactions, rather than the modeler through a limited set of expressions. Here, we discuss the role of electronic coarse-graining in predictive multiscale materials modelling and describe the first implementation of the method in a general purpose molecular dynamics software: QDO-MD. - Highlights: • Electronic coarse graining unites many-body dispersion and polarisation beyond the dipole limit. • It consists of replacing the electrons of a molecule using a quantum harmonic oscillator, called a Quantum Drude Oscillator. • We present the first general implementation of Quantum Drude Oscillators in the molecular dynamics package QDO-MD. • We highlight the successful construction of a new, transferable molecular model of water: QDO-water. - Graphical abstract:.« less
  • Cited by 10
  • Cr-doped SrTi{sub 1-} {sub x} Cr {sub x} O{sub 3} (x=0.00, 0.02, 0.05, 0.10) powders, prepared by solvothermal method, were further characterized by ultraviolet-visible (UV-vis) absorption spectroscopy. The UV-vis spectra indicate that the SrTi{sub 1-} {sub x} Cr {sub x} O{sub 3} powders can absorb not only UV light like pure SrTiO{sub 3} powder but also the visible-light spectrum ({lambda}>420 nm). The results of density functional theory (DFT) calculation illuminate that the visible-light absorption bands in the SrTi{sub 1-} {sub x} Cr {sub x} O{sub 3} catalyst are attributed to the band transition from the Cr 3d to the Crmore » 3d+Ti 3d hybrid orbital. The photocatalytic activities of chromium-doped SrTiO{sub 3} both under UV and visible light are increased with the increase in the amounts of chromium. -- Graphical abstract: SrTi{sub 1-} {sub x} Cr {sub x} O{sub 3} powders, prepared by solvothermal method, can absorb not only UV light like pure SrTiO{sub 3} powder but also the visible-light spectrum ({lambda}>420 nm). The results of DFT calculation illuminate that the visible-light absorption bands in the SrTi{sub 1-} {sub x} Cr {sub x} O{sub 3} catalyst are attributed to the band transition from the Cr 3d to the Cr 3d+Ti 3d hybrid orbital.« less