Hydrogen production from water utilizing solar heat at high temperatures

Nakamura, Takuya

doi:10.1016/0038-092x(77)90102-5

Cited by 453 publications

(230 citation statements)

References 5 publications

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“…Because Ce is tetravalent in CeO 2 the presence of divalent Sr results in the under reduction of the O anions. This is demonstrated by Kroger-Vink notation shown in eqn (8) and explicitly shown in the PDOS of Fig. 3b.…”

Section: Non-performance Improving Materialsmentioning

confidence: 61%

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂

Muhich

Steinfeld

2017

J. Mater. Chem. A

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Ceria-based metal oxides are promising redox materials for solar H 2 O/CO 2 -splitting thermochemical cycles. Density functional theory (DFT) computations are applied to elucidate the underlying mechanism of the role of dopants in facilitating ceria based redox cycles; specifically, we explain why some dopants increase performance, while others do not. Firstly, we find that Zr and Hf dopants increase the oxygen exchange capacity of ceria because they store energy in tensilely strained Zr-or Hf-O bonds which is released upon O-vacancy formation. This finding corrects a long held assumption that Zr and Hf decrease the O-vacancy formation energy by compensating for ceria expansion upon reduction.Although the released strain energy decreases the O-vacancy formation energy, O-vacancy formation remains sufficiently endothermic to split H 2 O and CO 2 . Secondly, we show that two electrons must be promoted into the high energy Ce f-band during reduction if the O-vacancies are to store sufficient energy to drive the oxidative gas splitting step. This means that di-and trivalent dopants are not suitable for this process. Lastly, we show that dopants which break O bonds due to their small size or strongly covalent character, such as Ti and the pentavalent dopants, substantially decrease the O-vacancy formation energy because only three O bonds must break during reduction. These vacancies, therefore, are too low in energy to drive gas splitting. Based on these findings, we develop guidelines for new ceria doping strategies to facilitate solar thermochemical gas splitting cycles.

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Section: Non-performance Improving Materialsmentioning

confidence: 61%

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂

Muhich

Steinfeld

2017

J. Mater. Chem. A

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“…The ZnO/Zn as well as the Fe 3 O 4 /FeO redox pair have already been analyzed and tested in solar reactors [65,66,69,[71][72][73][74]. Both systems require the quenching of the reduction products in order to prevent re-oxidation.…”

Section: Thermochemical Cycles Under Considerationmentioning

confidence: 99%

Functioning devices for solar to fuel conversion

Mul¹,

Schacht²,

Swaaij³

et al. 2012

Chemical Engineering and Processing: Process Intensification

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a b s t r a c tThis paper provides a perspective on the technologies capable of converting solar energy, CO 2 and H 2 O into an easy to use fuel. The paper addresses bio-based approaches, but mainly focuses on (i) the combination of photovoltaic (PV) devices and electrocatalysis, (ii) single unit operation by photocatalytic conversion, and (iii) solar thermal conversion. Each option is described in a general manner, including a brief evaluation of the advantages and disadvantages. Also suggestions for future research endeavours are given. Based on the used literature data, for electrocatalytic and photocatalytic technologies, dramatic improvements should be made in material optimization, as well as reactor design and operation. Large efficiency gains are necessary to enable use of these technologies in practice. Solar thermal conversion is more mature, and requires specific optimization in processing, as will be discussed.

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“…Other spinel structures are also of interest, such as the ''hercynite cycle" (Muhich et al, 2013 (Haussener et al, 2010c). Gokon et al, 2008a;Han et al, 2007;Miller et al, 2008;Nakamura, 1977;Perkins and Weimer, 2004;Scheffe et al, 2010;Stamatiou et al, 2010;Steinfeld et al, 1999). The metal oxide active materials in solar thermal water splitting operate via either a stoichiometric reduction pathway or via nonstoichiometric oxygen vacancy mechanisms (Muhich et al, 2016b).…”

Section: Reaction Kineticsmentioning

confidence: 99%

Modelling of solar thermochemical reaction systems

et al. 2017

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a b s t r a c tThis article reviews the progress, challenges and opportunities in numerical modelling of thermal transport, thermochemical reactions and thermomechanics in high-temperature solar thermochemical systems. Continuum-scale models are presented in mathematical detail while highlighting the literature that uses them. The discussion is enhanced by selected examples of numerical studies of solar thermochemical systems for solar fuels and commodity material production. Property predictions necessary for the modelling of solar thermochemical reaction systems are covered.

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Hydrogen production from water utilizing solar heat at high temperatures

Cited by 453 publications

References 5 publications

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂

Functioning devices for solar to fuel conversion

Modelling of solar thermochemical reaction systems

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Hydrogen production from water utilizing solar heat at high temperatures

Cited by 453 publications

References 5 publications

Principles of doping ceria for the solar thermochemical redox splitting of H2O and CO2

Principles of doping ceria for the solar thermochemical redox splitting of H2O and CO2

Functioning devices for solar to fuel conversion

Modelling of solar thermochemical reaction systems

Contact Info

Product

Resources

About

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂

Principles of doping ceria for the solar thermochemical redox splitting of H₂O and CO₂