Activated interiors of clay nanotubes for agglomeration-tolerant automotive exhaust remediation

Naturally occurring clay nanotubes, halloysite (Al sub(2)Si sub(2)O sub(5)(OH) sub(4).2H sub(2)O), with exterior and interior surfaces, respectively, composed of SiO sub(x) and AlO sub(x) layers, act as an agglomeration-tolerant exhaust catalyst when copper-nickel alloy nanoparticles (Cu-Ni NPs, 2-3...

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Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2015-01, Vol.3 (12), p.6614-6619
Main Authors: Sanchez-Ballester, Noelia M, Ramesh, Gubbala V, Tanabe, Toyokazu, Koudelkova, Eva, Liu, Jia, Shrestha, Lok Kumar, Lvov, Yuri, Hill, Jonathan P, Ariga, Katsuhiko, Abe, Hideki
Format: Article
Language:English
Subjects:
Agglomeration
Catalysts
Clay (material)
Copper
Exhaust
Exteriors
Nanostructure
Nanotubes
Silicon dioxide
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Summary:Naturally occurring clay nanotubes, halloysite (Al sub(2)Si sub(2)O sub(5)(OH) sub(4).2H sub(2)O), with exterior and interior surfaces, respectively, composed of SiO sub(x) and AlO sub(x) layers, act as an agglomeration-tolerant exhaust catalyst when copper-nickel alloy nanoparticles (Cu-Ni NPs, 2-3 nm) are immobilized at the AlO sub(x) interior. Co-reduction of Cu super(2+) and Ni super(2+) (respectively derived from CuCl sub(2) and NiCl sub(2)) in the presence of sodium citrate (Na sub(3)C sub(6)H sub(5) O sub(7).2H sub(2)O) and halloysite yielded the required nanocomposite, Cu-Ni[at]halloysite. Cu-Ni[at]halloysite efficiently catalyzes the purification of simulated motor vehicle exhaust comprising nitrogen monoxide (NO) and carbon monoxide (CO) near the activation temperature of Pt-based exhaust catalysts, less than or equal to 400 degree C, showing its potential as an alternative to Pt-based catalysts. In contrast, a different halloysite nanocomposite with the SiO sub(x) exterior decorated with Cu-Ni NPs, Cu-Ni/halloysite, is poorly active even at >400 degree C because of particle agglomeration. The enhanced exhaust-purification activity of Cu-Ni[at]halloysite can ultimately be attributed to the topology of the material, where the alloy NPs are immobilized at the tubular AlO sub(x) interior and protected from particle agglomeration by the tubular form and SiO sub(x) exterior.
ISSN:2050-7488
2050-7496
DOI:10.1039/c4ta06966h