Synthetic fabrication of nanoscale MoS₂-based transition metal sulfides

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Fluorescent nanoparticles for sensing

Nanoparticle-based fluorescent sensors have emerged as a competitive alternative to small molecule sensors, due to their excellent fluorescence-based sensing capabilities. The tailorability of design, architecture, and photophysical properties has attracted the attention of many research groups, resulting in numerous reports related to novel nanosensors applied in sensing a vast variety of biological analytes. Although semiconducting quantum dots have been the best-known representative of fluorescent nanoparticles for a long time, the increasing popularity of new classes of organic nanoparticle-based sensors, such as carbon dots and polymeric nanoparticles, is due to their biocompatibility, ease of synthesis, and biofunctionalization capabilities. For instance, fluorescent gold and silver nanoclusters have emerged as a less cytotoxic replacement for semiconducting quantum dot sensors. This chapter provides an overview of recent developments in nanoparticle-based sensors for chemical and biological sensing and includes a discussion on unique properties of nanoparticles of different composition, along with their basic mechanism of fluorescence, route of synthesis, and their advantages and limitations

Fluorescent carbon dots from mono- and polysaccharides:synthesis, properties and applications

Fluorescent carbon dots (FCDs) are an emerging class of nanomaterials made from carbon sources that have been hailed as potential non-toxic replacements to traditional semiconductor quantum dots (QDs). Particularly in the areas of live imaging and drug delivery, due to their water solubility, low toxicity and photo- and chemical stability. Carbohydrates are readily available chiral biomolecules in nature which offer an attractive and cheap starting material from which to synthesise FCDs with distinct features and interesting applications. This mini-review article will cover the progress in the development of FCDs prepared from carbohydrate sources with an emphasis on their synthesis, functionalization and technical applications, including discussions on current challenges

Recent Advances in Graphene Based TiO2 Nanocomposites (GTiO2Ns) for Photocatalytic Degradation of Synthetic Dyes

Synthetic dyes are widely used in textile, paper, food, cosmetic, and pharmaceutical industries. During industrial processes, some of these dyes are released into the wastewater and their successive release into rivers and lakes produces serious environmental problems. TiO2 is one of the most widely studied and used photocatalysts for environmental remediation. However, it is mainly active under UV-light irradiation due to its band gap of 3.2 eV, while it shows low efficiency under the visible light spectrum. Regarding the exploration of TiO2 activation in the visible light region of the total solar spectrum, the incorporation of carbon nanomaterials, such as graphene, in order to form carbon-TiO2 composites is a promising area. Graphene, in fact, has a large surface area which makes it a good adsorbent for organic pollutants removal through the combination of electrostatic attraction and π-π interaction. Furthermore, it has a high electron mobility and therefore it reduces the electron-hole pair recombination, improving the photocatalytic activity of the semiconductor. In recent years, there was an increasing interest in the preparation of graphene-based TiO2 photocatalysts. The present short review describes the recent advances in TiO2 photocatalyst coupling with graphene materials with the aim of extending the light absorption of TiO2 from UV wavelengths into the visible region, focusing on recent progress in the design and applications in the photocatalytic degradation of synthetic dyes

DNA-templated nanowires for sensing volatile organic compounds

PhD ThesisThe fabrication of gas sensors with semi-conducting nanowires has attracted considerable interest in recent times because of their potential of selective and fast detection of low quantities of gaseous analyte when incorporated into miniature and low-power consumer electronics. DNA templating is a relatively new process for fabrication of nanowires at room temperature without the requirement for vacuum technology. This thesis describes the synthesis, characterization and gas sensing application of DNA templated metal sulfides and carbon nanotube nanowires. DNA templated CdS, CdZnS2 and ZnS were synthesized in solution to form smooth and continuous nanowires.The reaction involves initial coordination of the metal ion(s) with DNA and subsequent co-precipitation with sulfide ions upon addition of Na2S.The nanowires were deposited on the substrate via molecular combing to form a wellaligned network for electrical characterisation and gas sensing experiments. The structure, chemical composition and morphology of the nanowires were characterised by atomic force microscopy (AFM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, photoluminescence (PL), fluorescence microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. These techniques showed that the metal sulfides interact with the DNA template to form microcrystalline nanowires of typical diameter < 10 nm and controllable Cd:Zn ratio. The current-voltage (I-V) properties as a function of temperature were measured using micro-band electrodes on a probe station, Impedance spectroscopy and current transients were used to estimate contact resistances. The nanowires showed weak conductivity with I-V curves typical of metalsemiconductor-metal systems and described by the space charge limited conduction model. The temperature dependent properties of the nanowires showed simple Arrhenius behaviour. The room temperature sensing properties of the nanowires to volatile organic compounds (VOCs) such as ethanol, acetone, chloroform and hexane were also determined. They demonstrated good and reversible sensing response to the VOCs but with a higher sensitivity towards ethanol. The result also suggests that the room temperature sensing mechanism of the VOCs molecules on CdS/DNA, ZnS/DNA and CdZnS2/DNA nanowire sensor is essentially driven by their direct adsorption on the surface and interaction with charges in the nanowires

Active removal of waste dye pollutants using Ta[sub]3N[sub]5/W[sub]18O[sub]49 nanocomposite fibres

A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta3N5 nanoparticles and WOx≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W18O49. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta3N5 nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W18O49 component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors’ knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale

Ag NPs-based SERS substrates with high stability and sensitivity for practical applications

表面增强拉曼光谱（surfaceenhancedRamanspectroscopy，SERS）因具有单分子水平的高灵敏度，指纹图谱的高能量分辨率，衍射极限的空间分辨率和水环境友好等特点，在表面科学、分析科学和生物医学等方面获得了广泛的应用。随着便携式拉曼光谱仪器的问世，SERS在食品安全、环境监测、国防和公共安全等领域的应用前景也越发为研究者所关注。然而，迄今为止，SERS技术通常仅局限于这些领域的实验室基础研究，对于在实际体系中的应用还存在着许多问题。特别是如何获得高灵敏、高稳定、高重现性和易商品化的SERS基底，已成为SERS领域的热点和重点之一，是SERS面向实际应用的基石和瓶颈。 因...Surface enhanced Raman spectroscopy has a wide application in fields such as surface science, analytical science and biomedicine for its high sensitivity up to single molecule level, high-energy resolution of fingerprint spectra, spatial resolution nearing diffraction limit and little interference from water and so on. With the advent of portable Raman spectrometer, SERS has attracted much attenti...学位：工学硕士院系专业：化学化工学院_应用化学学号：2052012115158

Rare earth based nanostructured materials: Synthesis, functionalization, properties and bioimaging and biosensing applications

Rare earth based nanostructures constitute a type of functional materials widely used and studied in the recent literature. The purpose of this review is to provide a general and comprehensive overview of the current state of the art, with special focus on the commonly employed synthesis methods and functionalization strategies of rare earth based nanoparticles and on their different bioimaging and biosensing applications. The luminescent (including downconversion, upconversion and permanent luminescence) and magnetic properties of rare earth based nanoparticles, as well as their ability to absorb X-rays, will also be explained and connected with their luminescent, magnetic resonance and X-ray computed tomography bioimaging applications, respectively. This review is not only restricted to nanoparticles, and recent advances reported for in other nanostructures containing rare earths, such as metal organic frameworks and lanthanide complexes conjugated with biological structures, will also be commented on.European Union 267226Ministerio de Economía y Competitividad MAT2014-54852-