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Two-dimensional (2D) zinc oxide (ZnO) has attracted much attention for its potential applications in electronics, optoelectronics, ultraviolet photodetectors, and resistive sensors. However, little attention has been focused on the growth mechanism, which is highly desired for practical applications. In this paper, the growth mechanism of 2D ZnO by surfactant-assisted ion-layer epitaxy (SA-ILE) is explored by controlling the amounts of surfactant, temperature, precursor concentration, and growth time. It is found that the location and the number of nucleation sites at the initial stages are restricted by the surfactant, which absorbs Zn2+ ions via electrostatic attraction at the water-air interface. Then, the growth of 2D ZnO is administered by the temperature, precursors, and growth time. In other words, the temperature is connected with the diffusion of solute ions and the number of nucleation sites. The concentration of precursors determines the solute ions in solution, which plays a dominant role in the growth rate of 2D ZnO, while growth time affects the nucleation, growth, and dissolution processes of ZnO. However, if the above criteria are exceeded, the nucleation sites significantly increase, resulting in multiple 2D ZnO with tiny size and multilayers. By optimizing the above parameters, 2D ZnO nanosheets with a size as large as 20 μm are achieved with 10 × 10−5 of the ratio of sodium oleyl sulfate to Zn2+, 70 °C, 50 mM of precursor concentration, and 50 min of growth time. 2D ZnO sheets, are confirmed by scanning electron microscope (SEM), energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectrum. Our work might guide the development of SA-ILE and pave the platform for practical applications of 2D ZnO on photodetectors, sensors, and resistive switching devices.

We implemented a simple and inexpensive aqueous sol-gel process to synthesize ZnAl2O4 nanoparticles to study its potential application as a gas sensor. Compared to traditional ceramic methods, the synthesis was conducted at lower temperatures and reaction times (5 h from 200 °C). The crystalline evolution of the oxide was investigated. The effect of the calcination temperature (200–1000 °C) on the crystallites’ size (16–29 nm) and the ZnAl2O4 powder’s surface morphology was also analyzed. Measurements confirmed the formation of bar-shaped granules (~0.35 μm) made up of nanoparticles (~23 nm). The surface area of the powders was 60 m2/g. Pellets were made from the powders and tested in sensing carbon monoxide and propane gases, showing a high sensitivity to such gases. The sensor’s response increased with increasing temperature (25–300 °C) and gas concentration (0–300 ppm). The oxide showed a higher response in propane than in carbon monoxide. We concluded that the ZnAl2O4 is a good candidate for gas sensing applications.

Controlling the morphology and magnetic properties of CoFe2O4 nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe2O4 nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe2O4 nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe2O4 nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe2O4 nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe2O4 nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe2O4 nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe2O4 nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe2O4 magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.

This review provides a comprehensive overview of the recent advances in the various typical spinel ferrite-based thin films with controlled synthesis, their performances, applications in multifunctional material fields, fundamental scientific challenges, and beyond. Firstly, the crystal structures of spinel ferrite-based thin films are introduced. Secondly, recent progress in traditional synthesizing and novel methods for preparation of spinel ferrite-based films are highlighted. Thirdly, their magnetism, electricity, optics performances, and applications in advanced information technology, energy storage and conversion, and environmental conservation fields are also summarized and discussed in-depth. Some effective strategies for optimizing performances and further applications are summarized. Finally, the present review work ends with a short discussion concerning the challenges, opportunities, and future prospects of spinel ferrite-based thin films.

Controlling the morphology and magnetic properties of CoFe2O4 nanoparticles is crucial for the synthesis of compatible materials for different applications. CoFe2O4 nanoparticles were synthesized by a solvothermal method using cobalt nitrate, iron nitrate as precursors, and oleic acid as a surfactant. The formation of CoFe2O4 nanoparticles was systematically observed by adjusting synthesis process conditions including reaction temperature, reaction time, and oleic acid concentration. Nearly spherical, monodispersed CoFe2O4 nanoparticles were formed by changing the reaction time and reaction temperature. The oleic acid-coated CoFe2O4 nanoparticles inhibited the growth of particle size after 1 h and, therefore, the particle size of CoFe2O4 nanoparticles did not change significantly as the reaction time increased. Both without and with low oleic acid concentration, the large-sized cubic CoFe2O4 nanoparticles showing ferromagnetic behavior were synthesized, while the small-sized CoFe2O4 nanoparticles with superparamagnetic properties were obtained for the oleic acid concentration higher than 0.1 M. This study will become a basis for further research in the future to prepare the high-functional CoFe2O4 magnetic nanoparticles by a solvothermal process, which can be applied to bio-separation, biosensors, drug delivery, magnetic hyperthermia, etc.

Since the very recent discovery of ferroic ordering under two dimensional limit, novel devices based on 2D ferroelectricity or ferromagnetism has attracted a lot of interests and are promising for next generation electronic and optoelectronic applications. We find that, below the transition temperature Tc ~320 K, ultrathin CuInP2S6 (CIPS) nanoflakes down to bilayer are still pyroelectric. Changing the temperature will lead to charge modification at the surface of CIPS. 2D pyroelectric nanogenerator is fabricated which can efficiently convert the pyroelectric charges into electrical current. This work will facilitate novel applications of pyroelectric and ferroelectric materials, including pyroelectric devices, thermal sensors, ultrathin nanogenerators and various van der Waals (vdW) heterostructure at room temperature. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This work was supported by the National Research Foundation Singapore under NRF award number NRF-RF2013-08, Tier 2 MOE2017-T2-2-136, Tier 2 MOE2016-T2-2-153, MOE2015-T2-2-007, Tier 1 RG7/18, Tier 1 RG4/17. X.F.L thanks the support from the Ministry of Science and Technology (2017YFA0205004 and 2016YFA0200700), National Natural Science Foundation of China (21673054 and 11874130), Natural Science Foundation of Beijing Municipality (4182076 and 4184109).

Immobilized enzymes are a significant technological approach to retain enzyme activity and reduce enzyme catalytic cost. In this work, trypsin-incorporated Zn3(PO4)2 hybrid nanoflowers were prepared via mild precipitation and coordination reactions. The controllable preparation of hybrid nanoflowers was achieved by systematically investigating the effects of the raw-material ratio, material concentration and reaction temperature on product morphology and physicochemical properties. The enzyme content of hybrid nanoflowers was about 6.5%, and the maximum specific surface area reached 68.35 m2/g. The hybrid nanoflowers exhibit excellent catalytic activity and environmental tolerance compared to free trypsin, which was attributed to the orderly accumulation of nanosheets and proper anchoring formation. Further, the enzyme activity retention rate was still higher than 80% after 12 repeated uses. Therefore, trypsin/Zn3(PO4)2 hybrid nanoflowers—which combine functionalities of excellent heat resistance, storage stability and reusability—exhibit potential industrial application prospects.

In this paper, we propose for the first time the synthesis of α-MoO3 nanorods in a one-step procedure at mild temperatures. By changing the growth parameters, the microstructure and controllable morphology of the resulting products can be customized. The average diameter of the as-prepared nanorods is about 200 nm. The electrochromic and capacitance properties of the synthesized products were studied. The results show that the electrochromic properties of α-MoO3 nanorods at 550 nm have 67% high transmission contrast, good cycle stability and fast response time. The MoO3 nanorods also exhibit a stable supercapacitor performance with 98.5% capacitance retention after 10,000 cycles. Although current density varies sequentially, the nanostructure always exhibits a stable capacitor to maintain 100%. These results indicate the as-prepared MoO3 nanorods may be good candidates for applications in electrochromic devices and supercapacitors.

Herein, α-Al2O3 supported Ag particles with controllable size distribution are prepared successfully by tuning of the calcination conditions through an impregnation method. The size of Ag particles could be adjusted by changing the calcination time and temperature. The catalyst samples were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and other characterization methods under different calcination conditions, and the performance differences of their catalytic reduction of p-nitrophenol (4-NP) were investigated by UV-Vis spectroscopy. The results show that the Ag particles with increased particle size can be obtained on the surface of α-Al2O3 support by increasing the calcination time or calcination temperature. The catalytic performance of the samples obtained by increasing the calcination time decreased, while the catalytic performance of the samples obtained by increasing the calcination temperature increased. This may be due to the interaction between Ag particles and the support, which changes the valence state of Ag species. Also the particle size effect acts on the catalyst and affects its catalytic performance together with the change of valence.

Controlled synthesis of hollow polymeric nanocapsules has attracted significant attention in a wide range of applications. This paper reports a facile method for the synthesis of hybrid starch nanocapsules decorated with silver nanoparticles using the inverse miniemulsion polyaddition technique. Silver nanoparticles are formed and embedded in the shell of the nanocapsules during the polyaddition process without using any additional reducing agents. We found that silver also acts as a lipophobe that builds up osmotic pressure in the droplets facilitating the formation of stable round shaped nanocapsules. The nanocapsules' shell thickness could be tuned from 13 to 29 nm by varying the amount of cross-linker. We investigated the minimum inhibitory concentration (MIC) of the nanocapsules against Staphylococcus epidermidis ATCC 35984 and Escherichia coli ATCC 25922 which are two bacteria of medical relevance. The silver nanoparticle decorated nanocapsules showed antibacterial properties against both bacteria at the MIC of 2.315 mu g mL(-1) while control nanocapsules without silver had no antibacterial activity. Refereed/Peer-reviewed

Zinc oxide (ZnO) nanoparticles have gained widespread interest due to their unique properties, making them suitable for a range of applications. Several methods for their production are available, and of these, controlled synthesis techniques are particularly favourable. Large-scale culturing of Chlorella vulgaris produces secretory carbohydrates as a waste product, which have been shown to play an important role in directing the particle size and morphology of nanoparticles. In this investigation, ZnO nanorods were produced through a controlled synthesis approach using secretory carbohydrates from C. vulgaris, which presents a cost-effective and sustainable alternative to the existing techniques. Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), and UV-Vis spectroscopy were used to characterise the nanorods. The prepared nanorods exhibited a broad range of UV absorption, which suggests that the particles are a promising broadband sun blocker and are likely to be effective for the fabrication of sunscreens with protection against both UVB (290&ndash, 320 nm) and UVA (320&ndash, 400 nm) radiations. The antimicrobial activity of the prepared nanorods against Gram-positive and Gram-negative bacteria was also assessed. The nanostructures had a crystalline structure and rod-like appearance, with an average length and width of 150 nm and 21 nm, respectively. The nanorods also demonstrated notable antibacterial activity, and 250 &mu, g/mL was determined to be the most effective concentration. The antibacterial properties of the ZnO nanorods suggest its suitability for a range of antimicrobial uses, such as in the food industry and for various biomedical applications.

An AgI dimer capped with labile organometallic diphosphorus ligands [Cp2Mo2(CO)4(η2‐P2)] (Cp=C5H5) acts as a highly pre‐organized molecular precursor to direct the construction of 1D or 2D, and 3D organometallic–organic hybrid coordination polymers upon reaction with ditopic pyridine‐based linkers. The formation of the supramolecular aggregates can be controlled by the stoichiometry of the organic molecules, and the mechanism is supported by DFT calculations.

Listeria monocytogenes (L. monocytogenes) has been recognized as one of the extremely hazardous and potentially life-threatening food-borne pathogens, its real-time monitoring is of great importance to human health. Herein, a simple and effective method based on platinum sensitized tin dioxide semiconductor gas sensors has been proposed for selective and rapid detection of L. monocytogenes. Pt doped SnO2 nanospheres with particular mesoporous hollow structure have been synthesized successfully through a robust and template-free approach and used for the detection of 3-hydroxy-2-butanone biomarker of L. monocytogenes. The steady crystal structure, unique micromorphology, good monodispersit, and large specific surface area of the obtained materials have been confirmed by X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and Photoluminescence spectra (PL). Pt doped SnO2 mesoporous hollow nanosphere sensors reach the maximum response of 3-hydroxy-2-butanone at 250°C. Remarkably, sensors based on SnO2 mesoporous hollow nanospheres with 0.16 wt% Pt dopant exhibit excellent sensitivity (Rair/Rgas = 48.69) and short response/recovery time (11/20 s, respectively) to 10 ppm 3-hydroxy-2-butanone at the optimum working temperature. Moreover, 0.16 wt% Pt doped SnO2 gas sensors also present particularly low limit of detection (LOD = 0.5 ppm), superb long-term stability and prominent selectivity to 3-hydroxy-2-butanone. Such a gas sensor with high sensing performance foresees its tremendous application prospects for accurate and efficient detection of foodborne pathogens for the food security and public health.

The therapeutic effect of existing antibacterial agents is weakening as bacterial resistance increases. Therefore, researchers should focus on exploring and developing new antibacterial materials. In this work, Ag nanowires (AgNWs) were synthesized using a hydrothermal method, and the optimal synthesis conditions were determined. The fabricated AgNWs were characterized, and their antibacterial effect was studied. The optimal AgNW synthesis conditions were as follows: reaction temperature of 130 °C, reaction time of 60 min, silver nitrate:trisodium citrate ratio of 1:7.5, and sodium dodecylsulfonate concentration of 1 mM. Under these conditions, the diameter and length of the synthesized AgNWs were approximately 40 ± 5 nm and approximately 10 ± 1.5 μm, respectively. The prepared AgNWs presented good dispersion and a face-centered cubic crystal structure, and nanocrystals preferentially grew along the (1 1 1) crystal plane direction. In addition, AgNWs exhibited a good antibacterial effect against Gram-positive (G+) bacteria, namely Staphylococcus aureus and Enterococcus faecalis, and Gram-negative (G-) bacteria, namely Escherichia coli and Klebsiella pneumoniae. The minimum inhibitory concentrations of AgNWs for the aforementioned bacteria strains were 9.38, 18.75, 4.69, and 1.17 μg/mL, respectively. Therefore, AgNWs were more sensitive against G- bacteria than against G+ bacteria. This work provides a good foundation for the use of AgNW as nanomaterial antibacterial agents.

Monodisperse TiO2 nanospheres with tunable,uniform structures have been synthesized using tetrabutyl titanate as the precursor via a hydrothermal method at 130 ℃.The diameter of TiO2 microspheres can be precisely controlled from tens to 1000 nm by adjusting the synthetic parameters,such as reaction time and pH value of the reaction solution..The samples were characterized by scanning electron microscopy (SEM),transmission electron microscopy (TEM),and X-ray diffraction (XRD).The results showed that the sample was amorphous structure.The crystallinity of TiO2 could be improved by further hydrothermal crystallization.The monodisperse TiO2 nanospheres are expected to be applied in the photocatalytic reaction,solar cell,photonic crystals and so on.

Organolead halide perovskites (e.g., CH3NH3PbI3) have caught tremendous attention for their excellent optoelectronic properties and applications, especially as the active material for solar cells. Perovskite crystal quality and dimension is crucial for the fabrication of high-performance optoelectronic and photovoltaic devices. Herein the controlled synthesis of organolead halide perovskite CH3NH3PbI3 nanoplatelets on SiO2/Si substrates is investigated via a convenient two-step vapor transport deposition technique. The thickness and size of the perovskite can be well-controlled from few-layers to hundred nanometers by altering the synthesis time and temperature. Raman characterizations reveal that the evolutions of Raman peaks are sensitive to the thickness. Furthermore, from the time-resolved photoluminescence measurements, the best optoelectronic performance of the perovskite platelet is attributed with thickness of ≈30 nm to its dominant longest lifetime (≈4.5 ns) of perovskite excitons, which means lower surface traps or defects. This work supplies an alternative to the synthesis of high-quality organic perovskite and their possible optoelectronic applications with the most suitable materials. Accepted version

In this work, the most discriminating synthesis-related impurities found in samples from seizures and controlled synthesis of the synthetic cannabinoid MDMB-CHMICA (methyl (S)-2-(1-(cyclohexylmethyl)-1H-indole-3-carboxamido)-3,3-dimethylbutanoate) were characterized. Based on 61 available powder samples of MDMB-CHMICA, 15 key-impurities were assessed, isolated in larger quantities via flash chromatography and structurally elucidated and characterized via high resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Apart from verifying the relation of the impurities to the major component, the interpretation of their chemical structures with distinct structural elements provided first insights into the manufacturing process and the precursor compounds used. Following liquid chromatography mass spectrometry analysis of the 15 key-impurities, the 61 seized samples of MDMB-CHMICA were evaluated and classified via multivariate data analysis based on the corresponding relative peak areas. In a second part of this work, stability tests and multiple controlled syntheses of MDMB-CHMICA were carried out to better understand variations in impurity signatures and to assess the significance of variations in the impurity patterns of seized samples. The last coupling step of the amino acid with 1-(cyclohexylmethyl)-1H-indole-3-carboxylic acid was performed using the coupling agents oxalyl chloride, thionyl chloride, and HATU. Furthermore, the impact of reaction time and temperature on the impurity profile were investigated. Overall, eight new impurities were found in the controlled syntheses and two degradation products of MDMB-CHIMCA were found in the course of the stability tests. Replicates of a synthesis conducted on the same day showed similar impurity signatures; on different days they showed discriminable signatures. The use of different coupling reagents or conditions gave clearly distinguishable impurity signatures.

Pt nanoparticles (Pt NPs) supported on carbon have been widely employed as electrocatalysts toward oxygen reduction reaction. The development of more efficient electrocatalysts that enable one to reduce or even not require the use of Pt is a central challenge. In addition to the control over the physical and chemical features of Pt NPs, metal support interactions can be employed to enhance activities via the generation and exposure of surface-active sites. In this context, we report herein the development of electrocatalysts composed of Pt NPs supported on TiO2 microspheres, that were subsequently impregnated onto carbon. We have found that, by optimizing the loading of Pt at the TiO2 surface, the electrocatalytic activity toward the ORR could be improved compared to that of the commercial Pt/C (E-TEK) material, even at lower Pt loadings. The enhancement in activities could be assigned to the balance between Pt loading and generation of reactive surface sites, such as adsorbed oxygenated species. Moreover, the utilization of TiO2 as support enabled improved stabilities relative to Pt/C (E-TEK). We believe that the results described herein may inspire the development of electrocatalysts for the ORR with improved activities and stabilities.

The present review focuses on the proteins and peptides at the interfaces of nanostructured metals and semiconductors as a result of their use in synthesis in-situ and functionalization of nanostructures. We start the review with an introduction about the peculiar properties of nanostructured materials and their applications. In the following, the chemical and structural properties of peptides and proteins that allow their use as reducing, stabilizing, and functionalization agents are discussed. P roteins and peptides have not only the chemical groups for the metal ion reducing but also provide templates for directing the crystalline growing of nanostructures to the desired shapes and sizes. Proteins and peptides are also used mainly for the stabilization and functionalization of a diversity of nanostructured materials providing properties such as biocompatibility, plasmon-enhanced catalysis, sensing, micro/nanomotors, spin filters, and others. Nanostructured materials of metal oxides have mainly been functionalized with proteins and peptides to gain specific properties such as light harvesting and spin filters. Herein, we described the synthesis and functionalization of some types of nanostructured materials by using peptides and proteins. In the last part of the review, it is discussed the perspectives and challenges for the use of proteins and peptides in Nanotechnology.

Most methods controlling size and shape of metal nanoparticles are chemical methods, and little work has been done using only plasma methods. Size- and shape-controlled synthesis of silver nanoparticles (Ag NPs) is proposed based on adjusting the gas bubble formation produced between two silver electrodes. The application of a voltage waveform with three different pulse widths during a plasma process in water can generate different gas bubble formations. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of Ag NPs synthesized using three different bubble formations reveal that spherical Ag NPs are synthesized when very tiny bubbles are generated between two electrodes or when only the grounded electrode is enveloped with large gas bubbles, but Ag nanoplates are synthesized when both electrodes are completely enveloped with large gas bubbles.

Magnetic nanoparticles provide a unique nanosystem for various smart therapy applications because of their biocompatibility, their nanostructures which can be prepared controllably to match with the interest of study and, specifically, their responses to an external magnetic field. Interests in utilizing magnetic nanoparticles for biomedical treatments originate from their external controllability of transportation and movement inside biological objects and magnetic heat generation which provide tremendous advantages for targeted drug delivery and controlled drug release as well as magnetic hyperthermia. Recent progress in synthesis and functionalization has led to the formation of various functional magnetic nanoparticles with controlled magnetic properties based on controlling their particle size, shape and composition. In this review, we focus on the synthesis, protection and functionalization of iron oxide-based magnetic nanoparticles in order to control magnetic properties of nanostructured systems. We also highlight the recent advances in the development of multifunctional therapeutic nanosystems combining magnetic nanoparticles and drugs as well as their superior efficacy in biomedical treatments with smart performance by including therapy and modulated drug delivery and release through magnetic heating.

Made available in DSpace on 2018-12-11T16:50:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The use of extensive, time-consuming synthesis and the cost of an additional element in synthesis makes difficult the synthesis of photocatalyst active under a broad wavelength range. We propose a synthesis method to obtain ZnO nanoparticles in distinctive morphologies, which lie to several photocatalytic activation conditions. The Zn precursor concentration, solvent, temperature and reaction time altered the ZnO particles morphologies. Although all synthesis parameters modification interferes in ZnO particle morphology, the most pronounced was Zn salt precursor concentration. The synthesis parameter did not interfere in the crystalline wurtzite ZnO phase and the optical characterization, indicating possibilities of ionic defects formations in ZnO lattice. The “3-D flower like” ZnO structure reaches 98% of discoloration under UV illumination and 42% under visible illumination of initial rhodamine-B concentration. The good UV and visible photocatalytic active confirms that with only the modification of synthesis method without any dopant element, ZnO structure is active in large wavelength range. IQ UNESP − São Paulo State University (Unesp) IBILCE UNESP − São Paulo State University (Unesp) EMBRAPA INSTRUMENTAÇÃO DQ UFSCar − Universidade Federal de São Carlos IQ UNESP − São Paulo State University (Unesp) IBILCE UNESP − São Paulo State University (Unesp) FAPESP: 2014/17343-0 FAPESP: 2015/04511-5 FAPESP: 2017/01267-1 CNPq: 444926/2014-3

University of Technology Sydney. Faculty of Science. With relatively large surface areas and tunable composition and morphology, nanoparticles possess unexpected properties comparing with their bulk counterparts. Controlled synthesis and fine-tuning of their composition, morphology, and surface properties are the fundamental cornerstones in nanoscience and nanotechnology towards optimized overall performance of a variety of nanoparticles discovered today. Lanthanide-doped upconversion nanoparticles (UCNPs) are a new family of luminescent nanomaterials attracting a large amount of research interests, because these materials are capable of converting two or more low-energy photons into one high-energy photon. The controlled synthesis of lanthanide-doped UCNPs with fine-tuning the size, shape and composition becomes the next grand challenge aiming to push their real applications. Also, heterogeneous structured UCNPs have the potential to integrate many different functionalities and positively enhance each property within one nanoscale platform. Direct size/shape/composition-control in the conventional synthesis process, however does remain a challenge via the one-pot wet chemical synthesis route. This thesis thus aims to establish new methods for the fabrication of UCNPs with fine-tuning the size, shape and composition. Then, I use these well-controlled nanocrystals to study the optical property at single nanocrystal level. Further, this knowledge is leveraged to develop a robust engineering protocol for fabrication of monodisperse multifunctional luminescent nanocrystals. The outcomes of this thesis not only include a series of knowledge discovered for controlled growth of lanthanide-doped nanomaterials, but also lead to a range of new applications demonstrated, such as super-resolution nanoscopy imaging, single-particle tracking, and multimodal bioimaging. This thesis begins with a comprehensive review of the size-/shape-dependent properties and the controlled wet-chemical synthesis of nanomaterials, especially for the recently developed UCNPs, forming the introduction Chapter 1. In Chapter 2, I provide the full details of materials and methods employed for seed-mediated growth in this thesis. And the following four chapters summarize the core results from 666 synthesis experiments to produce a range of homogeneous nanocrystals (Chapter 3), heterogeneous core@shell@shell nanocrystals (Chapter 5) and single directional grown barcoded nanorods at arbitrary sizes (Chapter 6), as well as a comprehensive characterization and investigation of crystal growth mechanisms (Chapter 4) that underpins these synthesis techniques. In Chapter 7, I summarize the key achievements presented in this thesis and discusses the potentials of using this developed approach for the fabrication of high-quality on-demand hybrid nanocrystals. Also, I discuss their potential application in new nanotechnologies, such as super-resolution imaging, multimodal bioimaging, optogenetics, nanothermometry, photovoltaics, and laser refrigeration.

This review describes some principles of the controlled synthesis of metal nanoparticles, focusing on how the fundamental understanding of their synthesis in the solution-phase can be put to tailor size, shape, composition, and architecture. The maneuvering over these parameters not only enable the tuning of properties, but also the maximization and optimization of performances for various applications. Herein, we start with a brief description of metallic nanoparticles, highlighting the motivation for achieving physicochemical control in their synthesis. After that, we turn our attention to some important definitions and classifications as well as their unique properties such as surface and quantum effects. Moreover, we discuss the strategies for the controlled synthesis of metal nanomaterials based on the top-down and bottom-up approaches, focusing our discussion on their formation mechanisms in liquid-phase in terms of both thermodynamic and kinetic control. Finally, we point out the promising applications of controlled nanomaterials in the field of nanocatalysis and plasmon-enhanced catalysis, describing some of the current challenges in these fields.

Lack of control on the chirality or diameter of single-wall carbon nanotubes (SWCNTs) during synthesisis a major impediment in the path of their widespread commercialization. We demonstrate that the humble technique of catalytic chemical vapor deposition of methane, without any sophisticated catalyst preparation, can provide significant control on the diameter of the synthesized SWCNTs. The catalyst used is a solid solution of the bimetals Fe-Mo or Co-Mo in MgO. The radial breathing modes (RBMs) in the Raman spectra of SWCNTs were used to find out the diameters. Kataura plot along with RBMs was used to study the chirality of the tubes. High concentration of the catalysts (Co: Mo: MgO = 1:0.5: 15 and Fe: Mo: MgO = 1: 0.5: 30) resulted in high yields. However, most of these carbonaceous materials were impurities. Reducing the concentration not only improved the purity and crystallinity (I-D/I-G ratio similar to 0.1), but most importantly reduced the diameter spread of the SWCNTs. Majority of the SWCNTs grown using the low concentration catalysts (Co: Mo: MgO = 1: 0.5: 300 and Fe: Mo: MgO = 1: 0.5: 200) were estimated to have diameters lying between 1.13 and 1.65 nm. This narrowing of diameter spread happened for both Fe and Co catalyst systems and depended only on the concentration of the catalyst. (C) 2014 Elsevier B.V. All rights reserved.

Controlled synthesis of CuO nanoparticles with various morphologies were achieved by a wet chemical method by the reduction of copper acetate with NaOH. Influence of surfactant, alkaline concentration and solvent medium on the morphology of nanoparticles was investigated. Our studies reveal that these parameters alter the aggregation-growth processes and hence the morphology. Sodium dodecyl sulphate (SDS) as a structure-guiding agent has a strong impact on the morphology of nanostructure. By adjusting the rate of hydrolysis, two dimensional netted structures consisting of bundles of nanorods were obtained, formed by oriented attachment mechanism. Moreover, well defined and dispersed CuO nanoparticles were produced by manipulating the solvent medium. Optical properties were studied using UV-Vis absorption and Raman spectroscopy. Morphology and size of nanoparticles have a profound effect on the nature of multi-phonon band observed in the Raman spectra of CuO nanostructures. � 2014 Elsevier B.V. All rights reserved.

Printable electronics and the increased use of nanoparticle products (e.g. quantum dots) has resulted in the rapid development of nanoparticle inks. Microfl uidic reactors ‐ or microreactors ‐ show promise to provide advanced control over size, size distribution and shape for commercial-scale synthesis of nanoparticles. Compared to batch-wise synthesis techniques primarily in use today, microfl uidic technology can provide better control of the reaction conditions, which is the key to controlling the product characteristics. [ 1 ] Handling small volumes of liquid allows better control of mixing, and hence yields more uniform chemical composition. For thermally activated syntheses, reagents can be heated and cooled rapidly and uniformly, avoiding the large thermal gradients typically found throughout the reaction volume in batch techniques. Several high-temperature microreactors for synthesizing nanoparticles have been described in the literature. [ 2 ] Almost all microreactors described to date have a

Information tagging and processing are vital in information-intensive applications, e.g. telecommunication and high-throughput drug screening. Magnetic suspension arrays technology may offer intrinsic advantages to screening applications by enabling high distinguishability, the ease of code generation and the feasibility of fast code readout, though the practical applicability of magnetic suspension arrays technology remains hampered by the lack of quality administration of encoded microcarriers. Here we realize a logic-controlled microfluidic system enabling controlled synthesis of magnetic suspension arrays in multiphase flow networks. The smart and compact system offers a practical solution for the quality administration and screening of encoded magnetic microcarriers and addresses the universal need of process control for synthesis in microfluidic networks, i.e. on-demand creation of droplet templates for high information capacity. The demonstration of magnetic suspension arrays technology enabled by magnetic in-flow cytometry opens the avenue toward point-of-care multiplexed bead-based assays, clinical diagnostics and drug discovery.

Van der Waals (vdW) solids, as a new type of artificial materials that consist of alternating layers bonded by weak interactions, have shed light on fascinating optoelectronic device concepts. As a result, a large variety of vdW devices have been engineered via layer-by-layer stacking of two-dimensional materials, although shadowed by the difficulties of fabrication. Alternatively, direct growth of vdW solids has proven as a scalable and swift way, highlighted by the successful synthesis of graphene/h-BN and transition metal dichalcogenides (TMDs) vertical heterostructures from controlled vapor deposition. Here, we realize high-quality organic and inorganic vdW solids, using methylammonium lead halide (CH3NH3PbI3) as the organic part (organic perovskite) and 2D inorganic monolayers as counterparts. By stacking on various 2D monolayers, the vdW solids behave dramatically different in light emission. Our studies demonstrate that h-BN monolayer is a great complement to organic perovskite for preserving its original optical properties. As a result, organic/h-BN vdW solid arrays are patterned for red light emitting. This work paves the way for designing unprecedented vdW solids with great potential for a wide spectrum of applications in optoelectronics.

A stable, Ag55 cluster protected with 4-(tert-butyl)benzyl mercaptan (BBSH) was synthesized which exhibits two prominent absorption bands with maxima at 2.25 and 2.81 eV. A molecular ion peak at m/z 11500 � 20 in matrix assisted laser desorption ionization mass spectrum (MALDI MS), assigned to Ag55(BBS)31 was observed. Electrospray ionization (ESI MS) shows a prominent trication along with higher charged species. An analogous Ag55(PET)31 (PET = 2-phenylethanethiol, in the thiolate form) was also synthesized under optimized conditions which proves the amenability of this cluster and the synthetic methodology to other ligands. � 2014 The Royal Society of Chemistry.

In the present research, large iron oxide microparticles with large sizes in the range of 1–5 μm have been facilely synthesized by a modified polyol method with NaBH4 as a versatile strong reducing agent. We found that the highly homogeneous iron oxide microparticles' novel structure is the best pure crystal phase of α-Fe2O3 in terms of polyhedral morphology and shape in existence. There are no diffraction peaks of other crystal phases from impurities in α-Fe2O3 microparticle products in the crystal growth. Interestingly, a new method of heat treatment or atomic surface deformation allowed for the discovery of a new large α-Fe2O3 structure with controlled specific α-Fe2O3 oxide grains in the crystal structure. The severe surface deformation of sharp, polyhedral, large α-Fe2O3 microparticles under a sintering treatment was found to give un-sharp, polyhedral large α-Fe2O3 microparticles with specific grains and boundaries.

We present our results obtained in the Rh-catalyzed carbene copolymerization of diazomethane and diazoesters as a new approach to functional polymer synthesis. Copolymerization reactions were successful, and high-Mw ethylene-acrylate type copolymers were obtained with a large variation in functional group content, which proved to be tunable by varying the monomer feed ratio and the way of addition. Polymer yields decrease strongly with increasing incorporation of diazomethane due to rapid β-hydride elimination. Sequential insertions of polar monomers were observed to a large extent, giving rise to copolymers with a blocky microstructure, which is a unique feature of this polymerization technique. The copolymer properties are demonstrated to be highly dependent on the functional group content and can therefore easily be varied in the window between the properties of both homopolymers.

Four linear amphiphilic multiblock copolymers based on 2-(dimethylamino) ethyl methacrylate (DMAEMA, hydrophilic) and methyl methacrylate (MMA, hydrophobic), bearing from two to five blocks, were synthesized using reversible addition - fragmentation chain transfer polymerization and stepwise monomer additions. The degree of polymerization of each hydrophilic poly DMAEMA block was ~50, while that of the hydrophobic polyMMA blocks was ca. 20. The stepwise monomer addition procedure secured that each higher multiblock was composed of its immediately lower homologue plus exactly one extra block. The molecular weights (MW) of the synthesized (co)polymers, as measured by gel permeation chromatography (GPC), were close to the theoretically expected. GPC also indicated rather narrow molecular weight distributions which, however, broadened with the number of blocks. The compositions of the copolymers, as determined by proton nuclear magnetic resonance spectroscopy, were also close to the expected values. The cloud points of the copolymers, measured by turbidimetry, were found to increase with the number of blocks. The sizes of the micelles formed by the copolymers in aqueous solution were characterized using dynamic light scattering and small-angle neutron scattering. The determined values of the hydrodynamic radii, the radii of gyration, and the aggregation numbers of the micelles increased slightly with the block number from the triblock to the pentablock copolymer, implying extensive folding of the chains of the tetrablock and the pentablock copolymers in their micelles. The aggregation number of the tetrablock copolymer was approximately one-half that of the diblock copolymer whose unimer MW was onehalf that of the tetrablock, suggesting that the micellar cores of these two types of micelles were composed of the same number of hydrophobic units. © 2010 American Chemical Society. 43 6 2713 2720 Cited By :33