Synthesis of Multifunctional Two-Dimensional Structures and Their Applications

Department of Energy EngineeringTwo dimensional (2D) materials with uniformly decorated heteroatoms represent a huge challenge and aroused immense interest beyond graphene due to their exceptional electronic and optoelectronic properties. The most widely studies 2D materials graphene and hexagonal boron nitride (h-BN) are the monoatomic layered materials with similar geometry and pole apart electronic structure and properties. Graphene is metallic due to extremely high carrier mobility and h-BN is wide band gap insulator, which limits their potential application in electronics. Despite recent explorations in materials science, an easy and scalable to produce uniformly doped 2D materials are limited. To overcome these problems, I first designed and synthesized a suitable monomer, hexaaminobenezene (HAB) hydrochloride, for the first time in crystalline form by using an easy procedure. The needle like crystal structure of the HAB hydrochlorides was confirmed by single crystal X-ray diffraction study. HAB was further used to fabricate a new layered 2D network structure with uniformly distributed holes and nitrogen atoms and the overall stoichiometry is thought to be C2N. The 2D structure can be efficiently prepared by simple wet-chemical reaction from the logically designed monomers. The structure of the C2N was confirmed by scanning tunneling microscopy (STM) and the calculated and experimental band-gaps are in the semiconductor region about 1.7 and 2.0 eV, suggesting a clear advantage over conducting graphene and insulating h-BN. I synthesized another 2D structure with C3N stoichiometry with uniformly placed nitrogen atoms in the carbon framework by carbonization of hexaaminobenezene hydrochloride single crystal at 500 °C. The topological and electronic structure of the C3N 2D structure was studied by scanning tunneling microscopy. C3N structure could be a new class of 2D materials with novel properties that can be emerged from the unique structure. C2N structure was used to encapsulate iron particles by in situ reducing and subsequent annealing to give Fe@C2N-h2D. Fe@C2N-h2D material shows interesting oxygen reduction reaction ability both in acid and alkaline solution. C2N structure was also used to encapsulate cobalt oxide by the same way for catalytic hydrogen evolution from the sodium borohydride solution. Co@C2N shows outstanding property of hydrogen evolution compared to the pure metal catalysts. Moreover, I also designed and synthesized organic conjugated triazine polymer demonstrating room temperature ferromagnetism derived from purely organic compounds. The polymer was synthesized through self-polymerization of tetracyanoquinodimethane (TCNQ). Electron spin resonance and magnetic characterization revealed the presence of spin ½ moments, which partially lead to ferromagnetic ordering with a critical temperature that is higher than room temperature.ope

Ruthenium anchored on carbon nanotube electrocatalyst for hydrogen production with enhanced Faradaic efficiency

Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen. For practical applications, an economical and facile method of producing catalysts for the hydrogen evolution reaction (HER) is essential. Here, we report ruthenium (Ru) nanoparticles uniformly deposited on multi-walled carbon nanotubes (MWCNTs) as an efficient HER catalyst. The catalyst exhibits the small overpotentials of 13 and 17 mV at a current density of 10 mA cm(-2) in 0.5M aq. H2SO4 and 1.0M aq. KOH, respectively, surpassing the commercial Pt/C (16 mV and 33 mV). Moreover, the catalyst has excellent stability in both media, showing almost "zeroloss" during cycling. In a real device, the catalyst produces 15.4% more hydrogen per power consumed, and shows a higher Faradaic efficiency (92.28%) than the benchmark Pt/C (85.97%). Density functional theory calculations suggest that Ru-C bonding is the most plausible active site for the HER

3-(3-Fluoro­benz­yl)isochroman-1-one

In the mol­ecule of the title compound, C16H13FO2, the aromatic rings are oriented at a dihedral angle of 74.46 (4)°. The heterocyclic ring adopts a twisted conformation. In the crystal structure, there is a weak C—H⋯π inter­action

Genetic Response of Different Genotypes of Sugarcane at Different Tissue Culture Techniques Combinations

Sugarcane is one of the major sugar crops of the world. Tissue culture study is mainly aimed to produce disease free plants. The study was carried out to find out the best combinations of tissue culture technique used for sugarcane to produce it asexually. It was also aimed to find out the best responsive genotype for tissue culture. From the five genotypes taken for the tissue culture study (HSF-242, CPF-246, CPF-247, S2002US-618, S2002US-718), Callogenesis study revealed significant differences for different genotypes and treatments. The genotype HSf-242 showed maximum callus formation at 3mg/l of 2, 4-D level but not best performance for organogenesis. For callus least performing genotype was S2002US-718. For organogenesis CPF-247 performed well at all treatments

Vertical two-dimensional layered fused aromatic ladder structure

Planar two-dimensional (2D) layered materials such as graphene, metal-organic frameworks, and covalent-organic frameworks are attracting enormous interest in the scientific community because of their unique properties and potential applications. One common feature of these materials is that their building blocks (monomers) are flat and lie in planar 2D structures, with interlayer -pi stacking, parallel to the stacking direction. Due to layer-to-layer confinement, their segmental motion is very restricted, which affects their sorption/desorption kinetics when used as sorbent materials. Here, to minimize this confinement, a vertical 2D layered material was designed and synthesized, with a robust fused aromatic ladder (FAL) structure. Because of its unique structural nature, the vertical 2D layered FAL structure has excellent gas uptake performance under both low and high pressures, and also a high iodine (I-2) uptake capacity with unusually fast kinetics, the fastest among reported porous organic materials to date. Stacking of planar layers composed of flat building blocks in two dimensional materials results in restriction of segmental motion which affects their typical properties, such as sorption or desorption. Here, the authors minimize this confinement using a vertically-stacked fused aromatic ladder structure and demonstrate excellent gas uptake under low and high pressure

Beyond survival: unraveling the adaptive mechanisms of cucurbit weeds to salt and heavy metal stress through biochemical and physiological analyses

Abstract Salt stress and heavy metal are instigating hazard to crops, menace to agricultural practices. Single and combined stresses affecting adversely to the growth and metabolism of plants. To explore salt and heavy metal resistant plant lines as phytoremediants is a need of time. Physiological responses are main adaptive responses of the plants towards stresses. This response varies with species and ecotype as well as type and level of stress. Two cucurbit weeds from two ecotypes were selected to evaluate their physiological adaptations against independent and combined stresses of various levels of salt (NaCl) and heavy metal (NiCl2). Various physiological parameters like water potential, osmotic potential, pressure potential, CO2 assimilation rate, stomatal conductance, chlorophyll a and b, carotenoids, and production of adaptive chemicals like SOD, CAT, proteins, sugars and proline were studied. Citrullus colocynthis showed more adaptive response than Cucumis melo agrestis and desert ecotype was more successful than agricultural ecotype against stresses

Porous two-dimentional crystalline graphene comprising nitrogen and method for preparing the same

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Method of synt hesizing Hexaaminobenzene

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