Nanosheet
A nanosheet is a two-dimensional nanostructure with thickness in a scale ranging from 1 to 100 nm.[1][2] A typical example of nanosheet is graphene, the thinnest two-dimensional material (0.34 nm) in the world.[3] It only consists of single layer of carbon atoms with hexagonal lattices.
Synthesis
The most commonly used nanosheet synthesis methods use a bottom-up approach, e.g., pre-organization and polymerization at interfaces like Langmuir–Blodgett films,[6] solution phase synthesis and chemical vapor deposition (CVD).[7] For example, CdTe (cadmium telluride) nanosheets could be synthesized by precipitating and aging CdTe nanoparticles in deionized water.[8] The formation of free-floating CdTe nanosheets was due to directional hydrophobic attraction and anisotropic electrostatic interactions caused by dipole moment and small positive charges. Molecular simulations through a coarse-grained model with parameters from semi-empirical quantum mechanics calculations can be used to prove the experimental process.
Ultrathin single-crystal PbS (lead sulfur) sheets with micro scale in x-, y- dimensions can be obtained using a hot colloidal synthesis method.[9] Compounds with linear chloroalkanes like 1,2-dichloroethane containing chlorine were used during the formation of PbS sheets. PbS ultrathin sheets probably resulted from the oriented attachment of the PbS nanoparticles in a two-dimensional fashion. The highly reactive facets were preferentially consumed in the growth process that led to the sheet-like PbS crystal growth.
Nanosheets can also be prepared at room temperature. For instance, hexagonal PbO (lead oxide)) nanosheets were synthesized using gold nanoparticles as seeds under room temperature.[4] The size of the PbO nanosheet can be tuned by gold NPs and Pb2+
concentration in the growth solution. No organic surfactants were employed in the synthesis process. Oriented attachment, in which the sheets form by aggregation of small nanoparticles that each has a net dipole moment,[10] and ostwald ripening[11] are the two main reasons for the formation of the PbO nanosheets.
Carbon nanosheets have been produced using industrial hemp bast fibres with a technique that involves heating the fibres at over 350F (180C) for 24 hours. The result is then subjected to intense heat causing the fibers to exfoliate into a carbon nanosheet. This has been used to create an electrode for a supercapacitor with electrochemical qualities ‘on a par with’ devices made using graphene.[12]
Metal nanosheets have also been synthesized from solution-based method by reducing metal precursors, including palladium,[13] rhodium,[14] and gold.[15]
See also
- Graphene
- Two-dimensional polymer
- Colloidal gold
- Nanocrystal solar cell
- Nanoparticle
- Quantum dot
- Langmuir–Blodgett film
References
- ↑ Coleman, J. N.; Lotya, M.; O'Neill, A.; Bergin, S. D.; King, P. J.; Khan, U.; Young, K.; Gaucher, A.; et al. (2011). "Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials". Science 331 (6017): 568–571. doi:10.1126/science.1194975. PMID 21292974.
- ↑ Guo, Shaojun; Dong, Shaojun (2011). "Graphene nanosheet: synthesis, molecular engineering, thin film, hybrids, and energy and analytical applications". Chemical Society Reviews 40 (5): 2644–2672. doi:10.1039/C0CS00079E. PMID 21283849.
- ↑ Geim, A. K. (2009). "Graphene: status and prospects". Science 324 (5934): 1530–1534. doi:10.1126/science.1158877. PMID 19541989.
- 1 2 Zeng, Shuwen; Liang, Yennan; Lu, Haifei; Wang, Libo; Dinh, Xuan-Quyen; Yu, Xia; Ho, Ho-Pui; Hu, Xiao; Yong, Ken-Tye (2012). "Synthesis of symmetrical hexagonal-shape PbO nanosheets using gold nanoparticles" (PDF). Materials Letters 67: 74–77. doi:10.1016/j.matlet.2011.09.048.
- ↑ Yin, Xi; Liu, Xinhong; Pan, Yung-Tin; Walsh, Kathleen A.; Yang, Hong (November 4, 2014). "Hanoi Tower-like Multilayered Ultrathin Palladium Nanosheets". Nano Letters. doi:10.1021/nl503879a.
- ↑ Synthesis of a Covalent Monolayer Sheet by Photochemical Anthracene Dimerization at the Air/Water Interface and its Mechanical Characterization by AFM Indentation; P. Payamyar, K. Kaja, C. Ruiz‐Vargas, A. Stemmer, D. J Murray, C. J Johnson, B. T. King, F. Schiffmann, J. VandeVondele, A. Renn, S. Götzinger, P. Ceroni, A. Schütz, L.‐T. Lee, Z. Zheng, J. Sakamoto, A. D. Schlüter, Adv. Mater 2014, 26, 2052–2058. doi:10.1002/adma.201304705
- ↑ Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting (2012). "Excitation of surface electromagnetic waves in a graphene-based Bragg grating". Scientific Reports 2. doi:10.1038/srep00737. PMC 3471096. PMID 23071901.
- ↑ Tang, Z.; Zhang, Z.; Wang, Y.; Glotzer, S. C.; Kotov, N. A. (2006). "Self-assembly of CdTe nanocrystals into free-floating sheets". Science 314 (5797): 274–278. doi:10.1126/science.1128045. PMID 17038616.
- ↑ Schliehe, C.; Juarez, B. H.; Pelletier, M.; Jander, S.; Greshnykh, D.; Nagel, M.; Meyer, A.; Foerster, S.; et al. (2010). "Ultrathin PbS sheets by two-dimensional oriented attachment". Science 329 (5991): 550–553. doi:10.1126/science.1188035. PMID 20671184.
- ↑ Talapin, Dmitri V.; Shevchenko, Elena V.; Murray, Christopher B.; Titov, Alexey V.; Král, Petr (2007). "Dipole-dipole interactions in nanoparticle superlattices". Nano Letters 7 (5): 1213–1219. doi:10.1021/nl070058c. PMID 17397231.
- ↑ Yang, Weiyou; Gao, Fengmei; Wei, Guodong; An, Linan (2010). "Ostwald Ripening Growth of Silicon Nitride Nanoplates". Crystal Growth & Design 10: 29–31. doi:10.1021/cg901148q.
- ↑ "Could hemp nanosheets topple graphene for making the ideal supercapacitor?". http://www.acs.org/. American Chemistry Society. Retrieved 14 August 2014. External link in
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(help) - ↑ Yin, Xi; Liu, Xinhong; Pan, Yung-Tin; Walsh, Kathleen; Yang, Hong (November 4, 2014). "Hanoi Tower-like Multilayered Ultrathin Palladium Nanosheets". Nano Letters. doi:10.1021/nl503879a.
- ↑ http://www.nature.com/ncomms/2014/140117/ncomms4093/full/ncomms4093.html
- ↑ http://pubs.acs.org/doi/abs/10.1021/jp0520998