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High-purity Cu nanocrystal synthesis by a dynamic decomposition method.

Jian X, Cao Y, Chen G, Wang C, Tang H, Yin L, Luan C, Liang Y, Jiang J, Wu S, Zeng Q, Wang F, Zhang C - Nanoscale Res Lett (2014)

Bottom Line: The growth was found to be influenced by the factors of reaction temperature, protective gas, and time.High crystalline Cu nanocrystals without floccules were obtained from thermal decomposition of cupric tartrate at 271°C for 8 h under Ar.This general approach paves a way to controllable synthesis of Cu nanocrystals with high purity.

View Article: PubMed Central - PubMed

Affiliation: Clean Energy Materials and Engineering Center, School of Energy Science and Engineering, University of Electronic Science and Technology of China, No. 2006, Xiyuan Avenue, West Hi-Tech Zone, Chengdu, 611731, China, jianxian@uestc.edu.cn.

ABSTRACT
Cu nanocrystals are applied extensively in several fields, particularly in the microelectron, sensor, and catalysis. The catalytic behavior of Cu nanocrystals depends mainly on the structure and particle size. In this work, formation of high-purity Cu nanocrystals is studied using a common chemical vapor deposition precursor of cupric tartrate. This process is investigated through a combined experimental and computational approach. The decomposition kinetics is researched via differential scanning calorimetry and thermogravimetric analysis using Flynn-Wall-Ozawa, Kissinger, and Starink methods. The growth was found to be influenced by the factors of reaction temperature, protective gas, and time. And microstructural and thermal characterizations were performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Decomposition of cupric tartrate at different temperatures was simulated by density functional theory calculations under the generalized gradient approximation. High crystalline Cu nanocrystals without floccules were obtained from thermal decomposition of cupric tartrate at 271°C for 8 h under Ar. This general approach paves a way to controllable synthesis of Cu nanocrystals with high purity.

No MeSH data available.


The images of optimization conformation of cupric tartrate (CuC4H4O6). After molecular dynamic course at the initial temperature from 273 ~ 673 K. (a) 273 K, (b) 373 K, (c) 473 K, (d) 573 K, (e) 623 K, and (f) 673 K.
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Fig8: The images of optimization conformation of cupric tartrate (CuC4H4O6). After molecular dynamic course at the initial temperature from 273 ~ 673 K. (a) 273 K, (b) 373 K, (c) 473 K, (d) 573 K, (e) 623 K, and (f) 673 K.

Mentions: In order to reveal the impetus of copper formation, it is necessary to investigate reaction mechanism of cupric tartrate, in particular to the decomposition kinetics, which is directly related to the formation of copper nanocrystals. However, the decomposition process of metallorganics can hardly be measured. We studied the molecular dynamic of cupric tartrate (CuC4H4O6) by density functional theory (DFT) calculations [32] with the generalized gradient approximation (GGA) of PBE [33], as implemented in the Dmol3 package [34]. The basis sets used in this work were double-numerical quality basis sets with polarization functions (DNP), which is comparable to the Gaussian 6–31 G** basis set in size and quality [35]. The global orbital cutoff scheme was used, and a 4.4 Å was assigned as global orbital cutoff. We optimized all possible isomers and calculated the binding energies. For nonperiodic systems of copper tartrate, only the NVE and NVT ensembles are available. In order to reasonably study the decomposition kinetics, NVT ensembles were used to control the reaction temperature, which fits well with the related experiments. To the energy-favored stable structure of cupric tartrate, molecular dynamic (MD) simulations were performed using the NVT ensemble (i.e., constant number of atoms, constant volume, and constant energy) which allows both the temperature and stress of the system to change during the decomposition. The molecular dynamic simulation was performed at the initial temperature range of 273 ~ 673 K using NVT ensemble, with a time step of 0.1 fs and simulation time of 0.2 ps. The two Cu-O bonds both increase with the temperature increasing from 273 ~ 673 K as shown in Figure 8. Compared with the original Cu-O bond length of 1.868 and 1.848 Å, the elongated bond length has the maximum value of 2.035 and 2.239 Å at 623 K, respectively, which demonstrates the formation of Cu atom. Besides, the length of a C-C bond elongates from 1.727 to 4.107 Å as the temperature increases up to 673 K. And then, molecular of cupric tartrate decomposes into a Cu atom, HCOOH, and C3O4H2 fragment. It can be speculated that Cu atoms generate from the cupric tartrate prior to the full decomposition of fragments which is in agreement with the fact that Cu nanocrystal and fragments coexist at relatively low temperatures.Figure 8


High-purity Cu nanocrystal synthesis by a dynamic decomposition method.

Jian X, Cao Y, Chen G, Wang C, Tang H, Yin L, Luan C, Liang Y, Jiang J, Wu S, Zeng Q, Wang F, Zhang C - Nanoscale Res Lett (2014)

The images of optimization conformation of cupric tartrate (CuC4H4O6). After molecular dynamic course at the initial temperature from 273 ~ 673 K. (a) 273 K, (b) 373 K, (c) 473 K, (d) 573 K, (e) 623 K, and (f) 673 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493849&req=5

Fig8: The images of optimization conformation of cupric tartrate (CuC4H4O6). After molecular dynamic course at the initial temperature from 273 ~ 673 K. (a) 273 K, (b) 373 K, (c) 473 K, (d) 573 K, (e) 623 K, and (f) 673 K.
Mentions: In order to reveal the impetus of copper formation, it is necessary to investigate reaction mechanism of cupric tartrate, in particular to the decomposition kinetics, which is directly related to the formation of copper nanocrystals. However, the decomposition process of metallorganics can hardly be measured. We studied the molecular dynamic of cupric tartrate (CuC4H4O6) by density functional theory (DFT) calculations [32] with the generalized gradient approximation (GGA) of PBE [33], as implemented in the Dmol3 package [34]. The basis sets used in this work were double-numerical quality basis sets with polarization functions (DNP), which is comparable to the Gaussian 6–31 G** basis set in size and quality [35]. The global orbital cutoff scheme was used, and a 4.4 Å was assigned as global orbital cutoff. We optimized all possible isomers and calculated the binding energies. For nonperiodic systems of copper tartrate, only the NVE and NVT ensembles are available. In order to reasonably study the decomposition kinetics, NVT ensembles were used to control the reaction temperature, which fits well with the related experiments. To the energy-favored stable structure of cupric tartrate, molecular dynamic (MD) simulations were performed using the NVT ensemble (i.e., constant number of atoms, constant volume, and constant energy) which allows both the temperature and stress of the system to change during the decomposition. The molecular dynamic simulation was performed at the initial temperature range of 273 ~ 673 K using NVT ensemble, with a time step of 0.1 fs and simulation time of 0.2 ps. The two Cu-O bonds both increase with the temperature increasing from 273 ~ 673 K as shown in Figure 8. Compared with the original Cu-O bond length of 1.868 and 1.848 Å, the elongated bond length has the maximum value of 2.035 and 2.239 Å at 623 K, respectively, which demonstrates the formation of Cu atom. Besides, the length of a C-C bond elongates from 1.727 to 4.107 Å as the temperature increases up to 673 K. And then, molecular of cupric tartrate decomposes into a Cu atom, HCOOH, and C3O4H2 fragment. It can be speculated that Cu atoms generate from the cupric tartrate prior to the full decomposition of fragments which is in agreement with the fact that Cu nanocrystal and fragments coexist at relatively low temperatures.Figure 8

Bottom Line: The growth was found to be influenced by the factors of reaction temperature, protective gas, and time.High crystalline Cu nanocrystals without floccules were obtained from thermal decomposition of cupric tartrate at 271°C for 8 h under Ar.This general approach paves a way to controllable synthesis of Cu nanocrystals with high purity.

View Article: PubMed Central - PubMed

Affiliation: Clean Energy Materials and Engineering Center, School of Energy Science and Engineering, University of Electronic Science and Technology of China, No. 2006, Xiyuan Avenue, West Hi-Tech Zone, Chengdu, 611731, China, jianxian@uestc.edu.cn.

ABSTRACT
Cu nanocrystals are applied extensively in several fields, particularly in the microelectron, sensor, and catalysis. The catalytic behavior of Cu nanocrystals depends mainly on the structure and particle size. In this work, formation of high-purity Cu nanocrystals is studied using a common chemical vapor deposition precursor of cupric tartrate. This process is investigated through a combined experimental and computational approach. The decomposition kinetics is researched via differential scanning calorimetry and thermogravimetric analysis using Flynn-Wall-Ozawa, Kissinger, and Starink methods. The growth was found to be influenced by the factors of reaction temperature, protective gas, and time. And microstructural and thermal characterizations were performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Decomposition of cupric tartrate at different temperatures was simulated by density functional theory calculations under the generalized gradient approximation. High crystalline Cu nanocrystals without floccules were obtained from thermal decomposition of cupric tartrate at 271°C for 8 h under Ar. This general approach paves a way to controllable synthesis of Cu nanocrystals with high purity.

No MeSH data available.