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Jikang Yuan

Bio: Jikang Yuan is an academic researcher from Hong Kong Polytechnic University. The author has contributed to research in topics: Molecular sieve & Capacitance. The author has an hindex of 22, co-authored 35 publications receiving 2989 citations. Previous affiliations of Jikang Yuan include Massachusetts Institute of Technology & University of Connecticut.

Papers
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Journal ArticleDOI
TL;DR: This work presents a self-assembly method for constructing thermally stable, free-standing nanowire membranes that exhibit controlled wetting behaviour ranging from superhydrophilic tosuperhydrophobic, and suggests an innovative material that should find practical applications in the removal of organics, particularly in the field of oil spill cleanup.
Abstract: The construction of nanoporous membranes is of great technological importance for various applications, including catalyst supports, filters for biomolecule purification, environmental remediation and seawater desalination. A major challenge is the scalable fabrication of membranes with the desirable combination of good thermal stability, high selectivity and excellent recyclability. Here we present a self-assembly method for constructing thermally stable, free-standing nanowire membranes that exhibit controlled wetting behaviour ranging from superhydrophilic to superhydrophobic. These membranes can selectively absorb oils up to 20 times the material's weight in preference to water, through a combination of superhydrophobicity and capillary action. Moreover, the nanowires that form the membrane structure can be re-suspended in solutions and subsequently re-form the original paper-like morphology over many cycles. Our results suggest an innovative material that should find practical applications in the removal of organics, particularly in the field of oil spill cleanup.

1,012 citations

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TL;DR: A new class of upconversion nanocrystals adopting an orthorhombic crystallographic structure in which the lanthanide ions are distributed in arrays of tetrad clusters is described, which enables the preservation of excitation energy within the sublattice domain and effectively minimizes the migration ofexcitation energy to defects.
Abstract: Lanthanide-doped nanocrystals can be used to upconvert infrared radiation into visible light, and are thought to be promising for a range of photonic and biological imaging applications. It is now shown that the upconversion efficiency can be improved by appropriately clustering the lanthanide ions on different structural sublattices.

482 citations

Journal ArticleDOI
TL;DR: Cryptomelane-type manganese oxide octahedral molecular (OMS) sieve three-dimensional nanostructures were synthesized via facile temple-free low-temperature hydrothermal reactions via slow oxidation of Mn(2+) by Cr(2)O(7)(-) under hydroThermal conditions is critical for the formation of the hierarchically ordered OMS-2 3D nanostructure.
Abstract: Cryptomelane-type manganese oxide octahedral molecular (OMS) sieve three-dimensional (3D) nanostructures were synthesized via facile temple-free low-temperature hydrothermal reactions. Morphologies of the cryptomelane-type OMS-2 nanoparticles with tunnel dimension of 4.6 x 4.6 A can be tuned by varying reaction temperatures. At low temperature (120 degrees C), OMS-2 dendritic nanoclusters composed of uniform single-crystal nanotetragonal prisms with square cross-sections were formed. At high temperature (180 degrees C), the morphologies of OMS-2 became spherical dandelion-like microspheres composed of uniform single-crystal OMS-2 nanoneedles. Slow oxidation of Mn(2+) by Cr(2)O(7)(-) under hydrothermal conditions is critical for the formation of the hierarchically ordered OMS-2 3D nanostructures.

236 citations

Journal ArticleDOI
TL;DR: In this article, a mechanism for the growth of manganese dioxides with 3D urchin-like architectures is proposed, where the crystal phases, shapes, and tunnel sizes of the manganized dioxide nanostructures can be tailored.
Abstract: Highly uniform single-crystal Na-OMS-2 (OMS: octahedral molecular sieve), pyrolusite, and γ-MnO2 nanostructures with an interesting 3D urchinlike morphology have been successfully prepared using a hydrothermal method based on a mild and direct reaction between sodium dichromate and manganese sulfate. The crystal phases, shapes, and tunnel sizes of the manganese dioxide nanostructures can be tailored. Reaction temperature, concentrations of the reactants, and acidity of the solution play important roles in controlling the synthesis of these manganese dioxides. Field-emission scanning electron microscopy and transmission electron microscopy (TEM) studies show that the nanomaterials obtained are constructed of self-assembled nanorods. X-ray diffraction and TEM results indicate that the constituent manganese dioxide particles are single-crystalline materials. Energy dispersive X-ray analysis and magnetic studies imply that chromium cations may be incorporated into the framework and/or tunnels of the manganese dioxides. A mechanism for the growth of manganese dioxides with urchinlike architectures is proposed.

214 citations

Journal ArticleDOI
TL;DR: The resulting material was mesoporous, crystalline, and of uniform diameter and could have applications as cathodic battery materials, oxidation catalysts, catalyst supports, and adsorbents for pollutants.
Abstract: Manganese oxide hollow nanospheres were prepared using a straightforward, template-free synthesis. The resulting material was mesoporous, crystalline, and of uniform diameter. The nanospheres were characterized by XRD, HR-SEM, and HR-TEM, and pore size distributions were calculated from nitrogen desorption. Unlike previous synthesis methods that use an inorganic template, this procedure requires no separation after synthesis to remove the template. The nanospheres are composed of hexagonal γ-manganese oxide flakes and are approximately 400 nm in diameter. γ-MnO2 is composed of a ramsdellite matrix (1 × 2 tunnels) with randomly distributed microdomains of pyrolusite (1 × 1 tunnels). These materials could have applications as cathodic battery materials, oxidation catalysts, catalyst supports, and adsorbents for pollutants.

213 citations


Cited by
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TL;DR: The unique advances on ultrathin 2D nanomaterials are introduced, followed by the description of their composition and crystal structures, and the assortments of their synthetic methods are summarized.
Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

3,628 citations

Journal ArticleDOI
TL;DR: Applications in Theranostics Guanying Chen,*,†,‡ Hailong Qiu,*,‡ and Xiaoyuan Chen.
Abstract: Applications in Theranostics Guanying Chen,*,†,‡ Hailong Qiu,†,‡ Paras N. Prasad,*,‡,§ and Xiaoyuan Chen* †School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China ‡Department of Chemistry and the Institute for Lasers, Photonics, and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York 14260, United States Department of Chemistry, Korea University, Seoul 136-701, Korea Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892-2281, United States

1,994 citations

Journal ArticleDOI
01 Jul 2010-ACS Nano
TL;DR: Graphene-based nanomaterials can effectively inhibit the growth of E. coli bacteria while showing minimal cytotoxicity and it is demonstrated that macroscopic freestanding GO and rGO paper can be conveniently fabricated from their suspension via simple vacuum filtration.
Abstract: Graphene is a monolayer of tightly packed carbon atoms that possesses many interesting properties and has numerous exciting applications. In this work, we report the antibacterial activity of two water-dispersible graphene derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets. Such graphene-based nanomaterials can effectively inhibit the growth of E. coli bacteria while showing minimal cytotoxicity. We have also demonstrated that macroscopic freestanding GO and rGO paper can be conveniently fabricated from their suspension via simple vacuum filtration. Given the superior antibacterial effect of GO and the fact that GO can be mass-produced and easily processed to make freestanding and flexible paper with low cost, we expect this new carbon nanomaterial may find important environmental and clinical applications.

1,741 citations

Journal ArticleDOI
Jing Zhou1, Qian Liu1, Wei Feng1, Yun Sun1, Fuyou Li1 

1,679 citations