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Efficient Electron Transfer in Functional Assemblies of Pyridine-Modified NQDs on SWNTs
Jeong, Sohee,Shim, Hyung Cheoul,Kim, Soohyun,Han, Chang-Soo American Chemical Society 2010 ACS NANO Vol.4 No.1
<P>Nanocrystal quantum dot (NQD)/single-walled carbon nanotube (SWNT) hybrid nanomaterials were synthesized, assembled into field effect transistors (FETs) <I>via</I> dielectrophoresis (DEP), and characterized optically and electronically. The pyridine moiety functioned as a short, noncovalent linker between the NQDs and SWNTs and allowed more efficient carrier transfer through the assemblies without deleteriously altering electronic structures. Photoluminescence studies of the resulting assemblies support an efficient carrier transfer process in CdSe-<I>py</I>-SWNTs unlike that of CdSe/ZnS-<I>py</I>-SWNTs. The use of DEP as a means of controlling the assembly process allowed the creation of a SWNT array containing densely packed CdSe NQDs across a 2 μm gap between electrodes. Observations and characterization of the photocurrent, resistivity, gate dependence, and optical properties of these systems suggest efficient electron transfer from photoexcited NQDs to SWNTs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-1/nn9009938/production/images/medium/nn-2009-009938_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn9009938'>ACS Electronic Supporting Info</A></P>
Transformative Two-Dimensional Layered Nanocrystals
Jeong, Sohee,Han, Jae Hyo,Jang, Jung-tak,Seo, Jung-wook,Kim, Jin-Gyu,Cheon, Jinwoo American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.37
<P>Regioselective chemical reactions and structural transformations of two-dimensional (2D) layered transition-metal chalcogenide (TMC) nanocrystals are described. Upon exposure of 2D TiS<SUB>2</SUB> nanodiscs to a chemical stimulus, such as Cu ion, selective chemical reaction begins to occur at the peripheral edges. This edge reaction is followed by ion diffusion, which is facilitated by interlayer nanochannels and leads to the formation of a heteroepitaxial TiS<SUB>2</SUB>–Cu<SUB>2</SUB>S intermediate. These processes eventually result in the generation of a single-crystalline, double-convex toroidal Cu<SUB>2</SUB>S nanostructure. Such 2D regioselective chemical reactions also take place when other ionic reactants are used. The observations made and chemical principles uncovered in this effort indicate that a general approach exists for building various toroidal nanocrystals of substances such as Ag<SUB>2</SUB>S, MnS, and CdS.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-37/ja2049594/production/images/medium/ja-2011-049594_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2049594'>ACS Electronic Supporting Info</A></P>
Sohee Cheon,Won Woo Lee,Won Il Park,Joo-Yun Jung,Jun-hyuk Choi,Dae-geun Choi,Sohee Jeon,Jun-ho Jeong,Jihye Lee 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-
Vertically aligned ZnO nanorods have been widely investigated for use in piezoelectric generators,photovoltaic devices, nanotemplates, photoelectrochemical applications, etc. In addition to verticalalignment, intentional arrangement of ZnO nanorods according to a careful design can enhance thedevice performance. In this work, we used metal nanotransfer printing to fabricate arrangement-controlled and vertically grown ZnO nanorods on both hard andflexible substrates. Highly verticalgrowth and periodical arrangement of the ZnO nanorods were confirmed by microscope images. Theircrystallinity and photoluminescence characteristics were also investigated. Transmission spectra of thesubstrates show the enhancement of optical transmission after the nanorod growth. We believe that thisfabrication technique lends itself to simple fabrication of arrangement-controlled and vertically grownone-dimensional nanostructures on both hard andflexible substrates for application in solar cells, watersplitting, metamaterials, etc.
Jeong, Sohee,Yoo, Dongwon,Jang, Jung-tak,Kim, Minkyoung,Cheon, Jinwoo American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.44
<P>While interesting and unprecedented material characteristics of two dimensionality (2-D) layered nanomaterials are emerging, their reliable synthetic methodologies are not well developed. In this study we demonstrate general applicability of synthetic protocols to a wide range of colloidal 2-D layered transition-metal chalcogenide (TMC) nanocrystals. As distinctly different from other nanocrystals, we discovered that 2-D layered TMC nanocrystals are unstable in the presence of reactive radicals from elemental chalcogen during the crystal formation. We first introduce the synthesis of titanium sulfide and selenide where well-defined single crystallinity and lateral size controllability are verified, and then such synthetic protocols are extended to all of group IV and V transition-metal sulfide (TiS<SUB>2</SUB>, ZrS<SUB>2</SUB>, HfS<SUB>2</SUB>, VS<SUB>2</SUB>, NbS<SUB>2</SUB>, and TaS<SUB>2</SUB>) and selenide (TiSe<SUB>2</SUB>, ZrSe<SUB>3</SUB>, HfSe<SUB>3</SUB>, VSe<SUB>2</SUB>, NbSe<SUB>2</SUB>, and TaSe<SUB>2</SUB>) nanocrystals. The use of appropriate chalcogen source is found to be critical for the successful synthesis of 2-D layered TMC nanocrystals. CS<SUB>2</SUB> is an efficient chalcogen precursor for metal sulfide nanocrystals, whereas elemental Se is appropriate for metal selenide nanocrystals. We briefly discuss the effects of reactive radical characteristics of elemental S and Se on the formation of 2-D layered TMC nanocrystals.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-44/ja3089845/production/images/medium/ja-2012-089845_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3089845'>ACS Electronic Supporting Info</A></P>
Jeong, Sohee,Rhee Paeng, Insook The Scientific World JOURNAL 2012 The Scientific World Journal Vol.2012 No.-
<P>A competitive enzyme-linked aptamer assay (ELAA) to detect tetracycline in milk was performed by using two different aptamers individually; one is 76 mer-DNA aptamer and the other is 57 mer-RNA aptamer. The best optimum condition was obtained without monovalent ion, Na<SUP>+</SUP> and also by adding no Mg<SUP>2+</SUP> ion in the assay buffer, along with RT incubation. The optimized ELAA showed a good sensitivity (LOD of 2.10 × 10<SUP>−8</SUP> M) with a wide dynamic range (3.16 × 10<SUP>−8</SUP> M ~ 3.16 × 10<SUP>−4</SUP> M). In addition, the average R.S.D. across all data points of the curve was less than 2.5% with good recoveries (~101.8%) from the milk media. Thus, this method provides a good tool to monitor tetracycline in milk from MRLs' point of view. However, this ELAA method was not superior to the ELISA method in terms of specificity. This paper describes that it does not always give better sensitivity and specificity in assays even though aptamers have several advantages over antibodies and have been known to be good binders for binding assays.</P>