Nanoparticle formation via copper (II) acetylacetonate vapor decompositionin the presence of hydrogen and water

Citation
Ag. Nasibulin et al., Nanoparticle formation via copper (II) acetylacetonate vapor decompositionin the presence of hydrogen and water, J PHYS CH B, 105(45), 2001, pp. 11067-11075
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
105
Issue
45
Year of publication
2001
Pages
11067 - 11075
Database
ISI
SICI code
1520-6106(20011115)105:45<11067:NFVC
Abstract
Copper (II) acetylacetonate (Cu(acac)(2)) vapor decomposition and subsequen t copper and copper (I) oxide particle formation were studied in a vertical laminar flow reactor in the presence of hydrogen and water vapor in a nitr ogen atmosphere. The presence of hydrogen does not significantly affect on the decomposition rate. The most reactive conditions for the precursor deco mposition appear when water vapor is introduced into the system. A mechanis m for Cu(acac)2 decomposition in the presence of water has been proposed. T he reaction pathway can be divided into three steps: formation of gaseous h ydrate complex; a proton transition from the coordinated water to a ligand and further liberation in the form of gaseous acetylacetone; the partial de struction (oxidation) of the resulting ligands and reduction reaction Of Cu 2+ to Cu-0. The formation of copper particles leads to a surface catalytic reaction of the organic decomposition products. As a result of this reactio n, low volatile long chain compounds containing ketone, alcohol, ester, and ether groups are formed. The crystallinity of the particles depends on the experimental conditions and changes from copper to copper (1) oxide when t he precursor vapor pressure is decreased from P-Cu(acac)2 = 6 to 0.13 Pa at t(furn) = 432 degreesC and the temperarture is increased to t(furn) = 705 degreesC at P-cu(acac)2 6 Pa. A qualitative thermodynamic explanation of th e change of crystalline phases is proposed. Primary particle size distribut ions were measured at t(furn) = 432 degreesC. The size of the particles is dependent on P-Cu(acac)2; the geometric mean diameter of D-p, = 27.3 nm (wi th geometric standard deviation of sigma (g) = 1.34) at P-Cu(acac)2 = 6 Pa, D-p = 15.6 mn (sigma (g) = 1.35) at P-Cu(acac)2 = 1.9 Pa, D-p = 5.2 mn (si gma (g) = 1.33) frond TEM images and D-p = 6.1 nm (sigma (g) = 1.35) from D MA measurements at P-Cu(acac)2 = 0.13 Pa, and D-p = 4.2 nm (sigma (g) = 1. 19) from DMA measurements at P-Cu(acac)2 = 0.07 Pa.