nanosheet

{{as of|2017}}, silicon nanosheets were being used to prototype future generations of small (5 nm) transistors.[http://uk.pcmag.com/news/89652/ibm-figures-out-how-to-make-5nm-chips IBM Figures Out How to Make 5nm Chips. June 2017]

Carbon nanosheets (from hemp) may be an alternative to graphene as electrodes in supercapacitors.

File:Palladium nanosheet on silicon wafer.jpg

The most commonly used nanosheet synthesis methods use a bottom-up approach, e.g., pre-organization and polymerization at interfaces like Langmuir–Blodgett films,{{cite journal | last1 = Payamyar | first1 = P. | last2 = Kaja | first2 = K. | last3 = Ruiz-Vargas | first3 = C. | last4 = Stemmer | first4 = A. | last5 = Murray | first5 = D. J | last6 = Johnson | first6 = C. J | last7 = King | first7 = B. T. | last8 = Schiffmann | first8 = F. | last9 = VandeVondele | first9 = J. | last10 = Renn | first10 = A. | last11 = Götzinger | first11 = S. | last12 = Ceroni | first12 = P. | last13 = Schütz | first13 = A. | last14 = Lee | first14 = L.-T. | last15 = Zheng | first15 = Z. | last16 = Sakamoto | first16 = J. | last17 = Schlüter | first17 = A. D. | year = 2014 | title = Synthesis of a Covalent Monolayer Sheet by Photochemical Anthracene Dimerization at the Air/Water Interface and its Mechanical Characterization by AFM Indentation | journal = Adv. Mater. | volume = 26 | issue = 13| pages = 2052–2058 | doi = 10.1002/adma.201304705 | pmid = 24347495 }} solution phase synthesis and chemical vapor deposition (CVD).{{cite journal|title=Excitation of surface electromagnetic waves in a graphene-based Bragg grating |journal=Scientific Reports |year=2012|volume=2|pages=737 |doi =10.1038/srep00737|last2=Zeng|first2=Shuwen|last3=Shang|first3=Jingzhi|last4=Yong|first4=Ken-Tye|last5=Yu|first5=Ting|last1=Sreekanth|first1=Kandammathe Valiyaveedu|pmid=23071901|pmc=3471096|bibcode=2012NatSR...2E.737S}} For example, CdTe (cadmium telluride) nanosheets could be synthesized by precipitating and aging CdTe nanoparticles in deionized water.{{cite journal|title=Self-assembly of CdTe nanocrystals into free-floating sheets |journal=Science |year=2006|volume=314|pages=274–278|doi =10.1126/science.1128045|pmid=17038616 |last2=Zhang|first2=Z.|last3=Wang|first3=Y.|last4=Glotzer|first4=S. C.|last5=Kotov|first5=N. A.|issue=5797|last1=Tang|first1=Z.|bibcode=2006Sci...314..274T}} 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.{{cite journal|title=Ultrathin PbS sheets by two-dimensional oriented attachment |journal=Science |year=2010|volume=329|pages=550–553|doi =10.1126/science.1188035|pmid=20671184 |last2=Juarez|first2=B. H.|last3=Pelletier|first3=M.|last4=Jander|first4=S.|last5=Greshnykh|first5=D.|last6=Nagel|first6=M.|last7=Meyer|first7=A.|last8=Foerster|first8=S.|last9=Kornowski|first9=A.|last10=Klinke |first10=C. |last11=Weller |first11=H. |issue=5991|last1=Schliehe|first1=C.|display-authors=8 |arxiv=1103.2920|bibcode=2010Sci...329..550S}} 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. The size of the PbO nanosheet can be tuned by gold NPs and {{chem|Pb|2+}} 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,{{cite journal|title=Dipole-dipole interactions in nanoparticle superlattices |journal=Nano Letters |year=2007|volume=7|pages=1213–1219|doi =10.1021/nl070058c|pmid=17397231 |last2=Shevchenko|first2=Elena V.|last3=Murray|first3=Christopher B.|last4=Titov|first4=Alexey V.|last5=Král|first5=Petr|issue=5|last1=Talapin|first1=Dmitri V.|bibcode=2007NanoL...7.1213T}}{{cite journal|last1=Tang|first1=Z.|last2=Zhang|first2=Z.|last3=Wang|first3=Y.|last4=Glotzer|first4=S. C.|last5=Kotov|first5=N. A.|date=13 October 2006|title=Self-Assembly of CdTe Nanocrystals into Free-Floating Sheets|journal=Science|volume=314|issue=5797|pages=274–278|doi=10.1126/science.1128045|pmid=17038616|bibcode=2006Sci...314..274T}} and ostwald ripening{{cite journal|title=Ostwald Ripening Growth of Silicon Nitride Nanoplates |journal=Crystal Growth & Design |year=2010|volume=10|pages=29–31|doi =10.1021/cg901148q|last2=Gao|first2=Fengmei|last3=Wei|first3=Guodong|last4=An|first4=Linan|last1=Yang|first1=Weiyou}} are the two main reasons for the formation of the PbO nanosheets. The same process was observed for iron sulfide nanoparticles.{{Cite journal|last=Bai|first=Yongxiao|last2=Yeom|first2=Jihyeon|last3=Yang|first3=Ming|last4=Cha|first4=Sang-Ho|last5=Sun|first5=Kai|last6=Kotov|first6=Nicholas A.|date=2013-02-14|title=Universal Synthesis of Single-Phase Pyrite FeS2 Nanoparticles, Nanowires, and Nanosheets|journal=The Journal of Physical Chemistry C|volume=117|issue=6|pages=2567–2573|doi=10.1021/jp3111106|issn=1932-7447}}

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.{{cite web|title=Could hemp nanosheets topple graphene for making the ideal supercapacitor?|url=http://www.acs.org/content/acs/en/pressroom/newsreleases/2014/august/could-hemp-nanosheets-topple-graphene-for-making-the-ideal-supercapacitor.html |website=acs.org|publisher=American Chemistry Society |access-date=14 August 2014}}

Metal nanosheets have also been synthesized from solution-based method by reducing metal precursors, including palladium,{{cite journal|last1=Yin|first1=Xi|last2=Liu|first2=Xinhong|last3=Pan|first3=Yung-Tin|last4=Walsh|first4=Kathleen|last5=Yang|first5=Hong|title=Hanoi Tower-like Multilayered Ultrathin Palladium Nanosheets|journal=Nano Letters|date=November 4, 2014|doi=10.1021/nl503879a|pmid=25369350|volume=14|issue=12|pages=7188–94|bibcode=2014NanoL..14.7188Y}} rhodium,{{cite journal | doi = 10.1038/ncomms4093 | volume=5 | title=Ultrathin rhodium nanosheets | journal=Nature Communications | pmid=24435210 | year=2014 | pages=3093 | last1 = Duan | first1 = H | last2 = Yan | first2 = N | last3 = Yu | first3 = R | last4 = Chang | first4 = CR | last5 = Zhou | first5 = G | last6 = Hu | first6 = HS | last7 = Rong | first7 = H | last8 = Niu | first8 = Z | last9 = Mao | first9 = J | last10 = Asakura | first10 = H | last11 = Tanaka | first11 = T | last12 = Dyson | first12 = PJ | last13 = Li | first13 = J | last14 = Li | first14 = Y| bibcode = 2014NatCo...5.3093D | doi-access = free }} and gold.{{cite journal | doi=10.1021/jp0520998 | pmid=16852818 | volume=109 | issue=30 | title=Synthesis of Single-Crystal Gold Nanosheets of Large Size in Ionic Liquids | journal=The Journal of Physical Chemistry B | pages=14445–14448| year=2005 | last1=Li | first1=Zhonghao | last2=Liu | first2=Zhimin | last3=Zhang | first3=Jianling | last4=Han | first4=Buxing | last5=Du | first5=Jimin | last6=Gao | first6=Yanan | last7=Jiang | first7=Tao }}

{{Portal|Science|Technology}}

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• Graphene
• Two-dimensional polymer
• Colloidal gold
• Nanocrystal solar cell
• Nanoparticle
• Quantum dot
• Langmuir–Blodgett film

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