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Facile microwave-assisted synthesis of Klockmannite CuSe nanosheets and their exceptional electrical properties.

Liu YQ, Wang FX, Xiao Y, Peng HD, Zhong HJ, Liu ZH, Pan GB - Sci Rep (2014)

Bottom Line: This is ascribed to the quantum size effect of NS and the presence of Schottky barrier.In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored.The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

View Article: PubMed Central - PubMed

Affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou, P. R. China.

ABSTRACT
Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200-500 nm × 400-800 nm and the thickness is 55 ± 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

No MeSH data available.


(a) Schematic illustration of the growth of CuSe nanosheets. (b) TEM image of single CuSe nanosheet. (c) Schematic diagram of the hexagonal crystal with the indexed facets.
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f5: (a) Schematic illustration of the growth of CuSe nanosheets. (b) TEM image of single CuSe nanosheet. (c) Schematic diagram of the hexagonal crystal with the indexed facets.

Mentions: Specifically, OM can act as not only an effective stabilizing ligand to protect the crystal from aggregating, but also a strong binding agent to template-guide the preferential growth of CuSe NSs (Fig. 5a). The introduction of octylamine enhances the templating effect and improves the yield of CuSe NSs (Fig. S7). Such a template-guided effect is also observed in the direct growth of ultrathin CuS nanosheets36, ultrathin ZnSe nanosheets37 and CdSe nanosheets38. On the other hand, the final shape of nanocrystals is determined by the ratio of the growth rates of different crystallographic planes. As for the hexagonal nanocrystals (Fig. 5b and 5c), it is mainly determined by the growth rates (R) along the [110], [010] and [100] directions. The classic BFDH model assumes the growth velocity (Rhkl) of a face on a growing polygon is approximately inversely proportional to the inter-planar spacing (dhkl)39. For CuSe NSs, d001 (17.25 Å) > d100 (3.41 Å) = d010 (3.41 Å) > d110 (1.97 Å), i.e., the growth rate sequence of R110 > R100 = R010 > R001. In addition, the crystal growth along the z axis proceeds slowly due to the weak van der Waals character between the layers. This leads to the formation of anisotropic 2D nanostructures oriented along the [001] direction. Thus, besides the templating effect of OM (and octylamine), the intrinsic crystal nature of klockmannite CuSe and different growth rates of exposed crystal planes are accounted for the evolution from small particles to hexagonal NSs.


Facile microwave-assisted synthesis of Klockmannite CuSe nanosheets and their exceptional electrical properties.

Liu YQ, Wang FX, Xiao Y, Peng HD, Zhong HJ, Liu ZH, Pan GB - Sci Rep (2014)

(a) Schematic illustration of the growth of CuSe nanosheets. (b) TEM image of single CuSe nanosheet. (c) Schematic diagram of the hexagonal crystal with the indexed facets.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126004&req=5

f5: (a) Schematic illustration of the growth of CuSe nanosheets. (b) TEM image of single CuSe nanosheet. (c) Schematic diagram of the hexagonal crystal with the indexed facets.
Mentions: Specifically, OM can act as not only an effective stabilizing ligand to protect the crystal from aggregating, but also a strong binding agent to template-guide the preferential growth of CuSe NSs (Fig. 5a). The introduction of octylamine enhances the templating effect and improves the yield of CuSe NSs (Fig. S7). Such a template-guided effect is also observed in the direct growth of ultrathin CuS nanosheets36, ultrathin ZnSe nanosheets37 and CdSe nanosheets38. On the other hand, the final shape of nanocrystals is determined by the ratio of the growth rates of different crystallographic planes. As for the hexagonal nanocrystals (Fig. 5b and 5c), it is mainly determined by the growth rates (R) along the [110], [010] and [100] directions. The classic BFDH model assumes the growth velocity (Rhkl) of a face on a growing polygon is approximately inversely proportional to the inter-planar spacing (dhkl)39. For CuSe NSs, d001 (17.25 Å) > d100 (3.41 Å) = d010 (3.41 Å) > d110 (1.97 Å), i.e., the growth rate sequence of R110 > R100 = R010 > R001. In addition, the crystal growth along the z axis proceeds slowly due to the weak van der Waals character between the layers. This leads to the formation of anisotropic 2D nanostructures oriented along the [001] direction. Thus, besides the templating effect of OM (and octylamine), the intrinsic crystal nature of klockmannite CuSe and different growth rates of exposed crystal planes are accounted for the evolution from small particles to hexagonal NSs.

Bottom Line: This is ascribed to the quantum size effect of NS and the presence of Schottky barrier.In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored.The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

View Article: PubMed Central - PubMed

Affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou, P. R. China.

ABSTRACT
Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200-500 nm × 400-800 nm and the thickness is 55 ± 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

No MeSH data available.