Carbon dots (CDs) with tunable fluorescence emissions have been developed from a wide range of small organic molecules with various bottom-up syntheses. However, most of them were prepared under high temperatures and high pressures with long reaction times and tedious purification processes. In addition, previously reported carbon dots frequently displayed excitation-dependent emissions, which restrict their further applications. Herein, we present a simple and rapid microwaveassisted solvothermal synthesis of multicolour carbon dots with excitation-independent emissions. In ethylene glycol, the green (G)-CDs emitting at 537 nm with a quantum efficiency (QY) of 15% were obtained by using a single precursor of phloroglucinol, and blue (B)- and yellow (Y)-CDs emitting at 436 nm and 557 nm with QYs of 55% and 28% were derived with additives of o- and m-phenylenediamine, respectively. Analyses of their chemical structures and optical processes suggest that highly polymeric carbon dots were uniformly formed from the small molecules and their fluorescences were predominantly originated from rapid direct recombination. Furthermore, emissions at different wavelengths were mainly attributed to different degrees of oxidation (13.9%, 15.2% and 16.4% oxygen in B-, G- and Y-CDs, respectively) and different proportions of pyrrolic nitrogen (10.4% and 1.40% in B- and Y-CDs, respectively). To demonstrate the application feasibility, the obtained carbon dots were utilized for ion detection and anti-counterfeiting. Based on static quenching of the carbon dots’ fluorescence, micro amounts of ferric ion in water samples were detected selectively and reproducibly. Moreover, the anti-counterfeiting pattern constructed by the carbon dots emitted fluorescence under ultraviolet illumination, but concealed perfectly under daylight. This achievement is of great potential for developing multicolour carbon dots of high qualities.

Pentachlorophenol (PCP), as one of the common pesticide and preservatives, is easily accumulated in living organisms. Considering the high toxicity of PCP, the development of an effective and sensitive inspection method to determine the residual trace amounts of PCP continues to be a significant challenge. Herein, a convenient and sensitive electrochemical sensor is constructed by modifying glassy carbon electrode with cerium dioxide ( CeO2) nanoparticles anchored graphene ( CeO2-GR) to detect trace PCP. Benefiting from the two-dimensional lamellar structural advantages, the extraordinary electron-transfer properties, as well as the intensive coupling effect between CeO2 nanoparticles and graphene, the afforded CeO2- GR electrode nanomaterial possesses excellent electrocatalytic activity for the oxidation of PCP. Under the optimum synthetic conditions, the PCP oxidation peak currents of developed CeO2– GR sample exhibit a wide linear range of 5–150 μM. Moreover, the corresponding detection limit of PCP on the CeO2– GR electrode is as low as 0.5 μM. Apart from providing a promising electrochemical sensor, this work, most importantly, promotes an efficient route for the construction of highly active sensing electrode materials.

Necessity of novel energy storage devices extensively increased due to consumption of high power in various devices. To address the issues, in this report, we are addressing with a composite Iron Sulfide/reduced Graphene Oxide ( Fe3S4/rGO) synthesized using the standard solvothermal method. X-ray diffraction and Field Emission Scanning Electron Microscope analysis results confirmed that Face-Centered cubic crystal structure of Fe3S4 and rGO’s surface is decorated with a mean diameter of < 50 nm Fe3S4 respectively. Transmission Electron Microscopy images show further evidence that dispersed Fe3S4 on the rGO surface. Fe3S4/ rGO exhibits specific capacitance of 560 F/g than its individual counterparts ( Fe3S4 = 200 F/g and rGO = 145 F/g) at 1 A/g of current density and maximum cyclic stability of 91% capacitance retention after 2000 cycles that may be the influence of synergy between the composite materials.

CeO2 nanoparticles, employed in a lot of fields due to their excellent oxidation and reduction properties, are synthesized through a solvothermal process, and a high specific surface area is shown by controlling, among various process parameters in the solvothermal process, the type of solvent. The synthesized CeO2 nanoparticles are about 11~13 nm in the crystallite size and their specific surface area is about 65.38~84.65 m2/g, depending on the amount of ethanol contained in the solvent for the solvothermal process; all synthesized CeO2 nanoparticles shows a fluorite structure. The dispersibility and microstructure of the synthesized CeO2 nanoparticles are investigated according to the species of dispersant and the pH value of the solution; an improvement in dispersibility is shown with the addition of dispersants and control of the pH. Various dispersing properties appear according to the dispersant species and pH in the solution with the synthesized CeO2 nanoparticles, indicating that improved dispersing properties in the synthesized CeO2 nanoparticles can be secured by applying dispersant and pH control simultaneously.

Nickel powders were prepared under solvothermal condition by precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at in a temperature range of 190-250 oC for 6h. The morphology and size of nickel powders were studied as a function of reaction temperature. The synthesis of nickel crystalline particles is possible under a solvothermal conditions in ethylene glycol solution. Characterization of the synthesized nickel powders were studied by XRD, SEM(FE-SEM) and TG/DSC. X-ray diffraction analysis of the synthesized powders indicated the formation of nickel structure after reaction. The average crystalline sizes of the synthesized nickel powders were in the range of 200-1000 nm; and the distribution of the powders was broad. The shape of the synthesized nickel particles was almost spherical. The morphology of synthesized nickel powders changed with reaction condition. It was possible to synthesize nickel powders directly in ethylene glycol without reducing agent.

본 연구에서는 용매열합성법(solvothermal method)을 이용해 나노기공 HKUST-1 분리막을 제조하였다. In-situ 용매열합성법을 이용하는 경우, 매크로 기공의 알루미나 지지체 위에 균일하고 균열이 없는 HKUST-1 층을 형성하기 어렵다. 본 연구에서는 용매열합성 전에 알루미나 지지체의 표면을 가열한 상태에서 용매열합성의 전구체 용액을 분무하므로 연속적이고 균열이 없는 HKUST-1 분리막을 제조할 수 있었다. 합성된 HKUST-1 분리막은 XRD, FE-SEM 및 단일 기체투과 실험 등을 통해 분석하였다.

Nickel oxide was doped with a wide range of concentrations (mol%) of Aluminum (Al) by solvothermal synthesis;single-phased nano powder of nickel oxide was generated after calcination at 900oC. When the concentration of Al dopant wasincreased, the reduced intensity was confirmed through XRD analysis. Lattice parameters of the synthesized NiO powder weredecreased after treatment of the dopant; parameters were increased when the concentration of Al was over the doping limit(5mol% Al). The binding energy of Ni2+ was chemically shifted to Ni3+ by doping Al3+ ion, as confirmed by the XPS analysis.The tilted structure of the synthesized NiO with 5mol% Al dopant and the polycrystalline structure of the Ni0.75Al0.25O wereobserved by HR-TEM analysis. The electrical conductivity of the newly synthesized NiO was highly improved by Al dopingin the conductivity test. The electrical conductivity values of the commercial NiO and the synthesized NiO with 5mol% Aldopant (Ni0.95Al0.05O) were 1,400s/cm and 2,230s/cm at 750oC, respectively. However, the electrical conductivity of thesynthesized NiO with 10mol% Al dopant (Ni0.9Al0.1O) decreased due to the scattering of free-electrons caused by the largenumber of impurity atoms; the electrical conductivity of Ni0.9Al0.1O was 545s/cm at 750oC.

Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently, many studies have focused on controlling the size and morphology of Y2O3 in order to obtain better material performance. Y2O3 powders were prepared under a modified solvothermal condition involving precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at temperatures at 250˚C after a 6h process. The properties of the Y2O3 powders were studied as a function of the solvent ratio. The synthesis of Y2O3 crystalline particles is possible under a modified solvothermal condition in a water/ethylene glycol solution. Solvothermal processing condition parameters including the pH, reaction temperature and solvent ratio, have significant effects on the formation, phase component, morphology and particle size of yttria powders. Ethylene glycol is a versatile, widely used, inexpensive, and safe capping organic molecule for uniform nanoparticles besides as a solvent. The characterization of the synthesized Y2O3 powders were studied by XRD, SEM (FE-SEM) and TG/DSC. An X-ray diffraction analysis of the synthesized powders indicated the formation of the Y2O3 cubic structure upon calcination. The average crystalline sizes and distribution of the synthesized Y2O3 powders was less than 2 um and broad, respectively. The synthesized particles were spherical and hexagonal in shape. The morphology of the synthesized powders changed with the water and ethylene glycol ratio. The average size and shape of the synthesized particles could be controlled by adjusting the solvent ratio.

Multilayer ceramic capacitor (MLCC) miniaturization has increased the demand for superfine powder due to its thin dielectric layer. Hydrothermally synthesized powder a pseudo-cubic phase resulting in poor dielectric properties due to size effect and hydroxyl ion inclusion in the lattice. We attempted a superfine (lower than 100 nm) highly tetragonal powder via a solvothermal method without precipitating agent. The lattice parameters and the relative amounts of tetragonal and cubic phases were determined using Rietveld refinement.