Reduction of Nano-Cu2O: Crystallite Size Dependent and the Effect of Nano-Ceria Support

Junhua Song, Philip P. Rodenbough, Wenqian Xu, Sanjaya D. Senanayake, Siu Wai Chan

Research output: Contribution to journalArticle

Abstract

Copper(I) oxide (Cu2O) is an effective catalyst in the CO oxidation reaction. While high surface to volume ratio in nanoparticles will increase their catalytic efficiency, it posts a stability problem. Here we study the stability of nano-cuprite against reduction as a function of its crystallite size and upon interaction with a nano-ceria support. A systematic analysis of isothermal reduction of a series size of monodispersed Cu2O nanocrystals (±7%) with time-resolved X-ray diffraction (TR-XRD) provides the time-resolved phase fraction of Cu2O and the time when reduction product of Cu (fcc) first appears. The initial phase fraction of nano-Cu2O is less than one with the balance attributed to an amorphous CuO shell. Since no peaks of crystalline CuO (monoclinic) were observed, a core-shell structure with an amorphous CuO shell is proposed. From the analysis, Cu2+ content in corresponding to shell increases from 0 to 33% as Cu2O decreases to 8 nm from the bulk. Based on the reduction profiles, a time size reduction (TSR) diagram is constructed for the observed Cu2O phase behavior during reduction. The incorporation onto a nano-CeO2 support (7 nm) significantly stabilizes our nano-Cu2O in a reducing atmosphere. The oxygen supply propensity in terms of oxygen nonstoichiometry of CeO2-y is shown to be lower when a larger crystallite size CeO2 (20 nm) support is used. The larger oxygen capacity in smaller nano-CeO2 support is analyzed and explained by the "Madelung model" with size-dependent bulk modulus of nano-ceria.

Original languageEnglish (US)
Pages (from-to)17667-17672
Number of pages6
JournalJournal of Physical Chemistry C
Volume119
Issue number31
DOIs
StatePublished - Aug 6 2015

Fingerprint

Cerium compounds
Crystallite size
oxygen
Oxygen
Oxygen supply
Copper oxides
Phase behavior
Carbon Monoxide
bulk modulus
Nanocrystals
nanocrystals
Elastic moduli
diagrams
Nanoparticles
Crystalline materials
catalysts
atmospheres
X ray diffraction
copper
Oxidation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Reduction of Nano-Cu2O : Crystallite Size Dependent and the Effect of Nano-Ceria Support. / Song, Junhua; Rodenbough, Philip P.; Xu, Wenqian; Senanayake, Sanjaya D.; Chan, Siu Wai.

In: Journal of Physical Chemistry C, Vol. 119, No. 31, 06.08.2015, p. 17667-17672.

Research output: Contribution to journalArticle

Song, Junhua ; Rodenbough, Philip P. ; Xu, Wenqian ; Senanayake, Sanjaya D. ; Chan, Siu Wai. / Reduction of Nano-Cu2O : Crystallite Size Dependent and the Effect of Nano-Ceria Support. In: Journal of Physical Chemistry C. 2015 ; Vol. 119, No. 31. pp. 17667-17672.
@article{37213e1a5c31450cb906e2596151943f,
title = "Reduction of Nano-Cu2O: Crystallite Size Dependent and the Effect of Nano-Ceria Support",
abstract = "Copper(I) oxide (Cu2O) is an effective catalyst in the CO oxidation reaction. While high surface to volume ratio in nanoparticles will increase their catalytic efficiency, it posts a stability problem. Here we study the stability of nano-cuprite against reduction as a function of its crystallite size and upon interaction with a nano-ceria support. A systematic analysis of isothermal reduction of a series size of monodispersed Cu2O nanocrystals (±7{\%}) with time-resolved X-ray diffraction (TR-XRD) provides the time-resolved phase fraction of Cu2O and the time when reduction product of Cu (fcc) first appears. The initial phase fraction of nano-Cu2O is less than one with the balance attributed to an amorphous CuO shell. Since no peaks of crystalline CuO (monoclinic) were observed, a core-shell structure with an amorphous CuO shell is proposed. From the analysis, Cu2+ content in corresponding to shell increases from 0 to 33{\%} as Cu2O decreases to 8 nm from the bulk. Based on the reduction profiles, a time size reduction (TSR) diagram is constructed for the observed Cu2O phase behavior during reduction. The incorporation onto a nano-CeO2 support (7 nm) significantly stabilizes our nano-Cu2O in a reducing atmosphere. The oxygen supply propensity in terms of oxygen nonstoichiometry of CeO2-y is shown to be lower when a larger crystallite size CeO2 (20 nm) support is used. The larger oxygen capacity in smaller nano-CeO2 support is analyzed and explained by the {"}Madelung model{"} with size-dependent bulk modulus of nano-ceria.",
author = "Junhua Song and Rodenbough, {Philip P.} and Wenqian Xu and Senanayake, {Sanjaya D.} and Chan, {Siu Wai}",
year = "2015",
month = "8",
day = "6",
doi = "10.1021/acs.jpcc.5b04121",
language = "English (US)",
volume = "119",
pages = "17667--17672",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "31",

}

TY - JOUR

T1 - Reduction of Nano-Cu2O

T2 - Crystallite Size Dependent and the Effect of Nano-Ceria Support

AU - Song, Junhua

AU - Rodenbough, Philip P.

AU - Xu, Wenqian

AU - Senanayake, Sanjaya D.

AU - Chan, Siu Wai

PY - 2015/8/6

Y1 - 2015/8/6

N2 - Copper(I) oxide (Cu2O) is an effective catalyst in the CO oxidation reaction. While high surface to volume ratio in nanoparticles will increase their catalytic efficiency, it posts a stability problem. Here we study the stability of nano-cuprite against reduction as a function of its crystallite size and upon interaction with a nano-ceria support. A systematic analysis of isothermal reduction of a series size of monodispersed Cu2O nanocrystals (±7%) with time-resolved X-ray diffraction (TR-XRD) provides the time-resolved phase fraction of Cu2O and the time when reduction product of Cu (fcc) first appears. The initial phase fraction of nano-Cu2O is less than one with the balance attributed to an amorphous CuO shell. Since no peaks of crystalline CuO (monoclinic) were observed, a core-shell structure with an amorphous CuO shell is proposed. From the analysis, Cu2+ content in corresponding to shell increases from 0 to 33% as Cu2O decreases to 8 nm from the bulk. Based on the reduction profiles, a time size reduction (TSR) diagram is constructed for the observed Cu2O phase behavior during reduction. The incorporation onto a nano-CeO2 support (7 nm) significantly stabilizes our nano-Cu2O in a reducing atmosphere. The oxygen supply propensity in terms of oxygen nonstoichiometry of CeO2-y is shown to be lower when a larger crystallite size CeO2 (20 nm) support is used. The larger oxygen capacity in smaller nano-CeO2 support is analyzed and explained by the "Madelung model" with size-dependent bulk modulus of nano-ceria.

AB - Copper(I) oxide (Cu2O) is an effective catalyst in the CO oxidation reaction. While high surface to volume ratio in nanoparticles will increase their catalytic efficiency, it posts a stability problem. Here we study the stability of nano-cuprite against reduction as a function of its crystallite size and upon interaction with a nano-ceria support. A systematic analysis of isothermal reduction of a series size of monodispersed Cu2O nanocrystals (±7%) with time-resolved X-ray diffraction (TR-XRD) provides the time-resolved phase fraction of Cu2O and the time when reduction product of Cu (fcc) first appears. The initial phase fraction of nano-Cu2O is less than one with the balance attributed to an amorphous CuO shell. Since no peaks of crystalline CuO (monoclinic) were observed, a core-shell structure with an amorphous CuO shell is proposed. From the analysis, Cu2+ content in corresponding to shell increases from 0 to 33% as Cu2O decreases to 8 nm from the bulk. Based on the reduction profiles, a time size reduction (TSR) diagram is constructed for the observed Cu2O phase behavior during reduction. The incorporation onto a nano-CeO2 support (7 nm) significantly stabilizes our nano-Cu2O in a reducing atmosphere. The oxygen supply propensity in terms of oxygen nonstoichiometry of CeO2-y is shown to be lower when a larger crystallite size CeO2 (20 nm) support is used. The larger oxygen capacity in smaller nano-CeO2 support is analyzed and explained by the "Madelung model" with size-dependent bulk modulus of nano-ceria.

UR - http://www.scopus.com/inward/record.url?scp=84938723603&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84938723603&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.5b04121

DO - 10.1021/acs.jpcc.5b04121

M3 - Article

AN - SCOPUS:84938723603

VL - 119

SP - 17667

EP - 17672

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 31

ER -