Papers by Keyword: Solvothermal

Abstract: This research aims to synthesize and characterize Ni(II)-terephthalate-pyrazine complex and to determine the thermal stability and porosity profile of the synthesized compound. The Ni(II)-terephthalate-pyrazine was made by solvothermal reaction using dimethylformamide at 130 and 150 °C and in Ni(II):terephthalic-acid:pyrazine mol ratios of 1:1:2 and 1:1:4. The precipitated products were characterized by infrared spectroscopy, SEM, and powder-XRD in order to confirm the presence of both ligand in the synthesized compound. Meanwhile, the thermal stability and porosity profile of the synthesized compound were determined by DTA-TGA and surface area analysers, respectively. Experimental data shows that green pale powder was obtained from all reactions in considerably good yield, which is different from the dark green crystalline solid of Ni(II)-terephthalate. SEM image reveals that the product has a smooth-wavy surface morphology. Infrared spectra of the synthesized compound show peaks of functional groups of C=O, C–O, C=N, and C–N groups, which confirm the presence of both ligands. Powder XRD analysis suggests that the crystal system of the synthesized compound is different from that of the Ni(II)-terephthalate. Based on these analyses, the targeted Ni(II)-terephthalate-pyrazine is successfully obtained. Moreover, the synthesized compound has lower thermal stability than that of Ni(II)-terephthalate, while the BET calculation suggest that the synthesized compound has pore volume of 0.10-0.14 cm³/g, pore diameter of 8.1-10.65 nm and surface area of 24-30 (m²/g). This porosity profile suggest that the synthesized compound is open for further application, such as adsorption or photocatalysis.

Abstract: Single crystal of [Ni(4-AP)₄(NCS)₂] complex compound has been obtained using solvothermal method at 70 °C for 15 hours (yield = 41%). Crystal structure of [Ni(4-AP)₄(NCS)₂] has a distorted octahedral structure with orthorhombic crystal system, Pccn space group, Z = 4, and a, b, and c values of 17.1091(5) Å, 9.6686 (3) Å, 16.1998 (5) Å. Hirshfeld Surface analysis shows that intermolecular hydrogen bonds in the complex compound comes from N–H∙∙∙∙N and N–H∙∙∙∙S. The intermolecular interactions are dominated by H---H, C---H/H---C, and H---S/S---H by 39.0%, 29.6%, and 24.7%, respectively. The relatively less contributions are N---H/H---N, S---C/C---S, and S---N/N---S at 6.3%, 0.2%, and 0.1%, respectively. The [Ni(4-AP)₄(NCS)₂] complex has antibacterial activity against Escherichia coli and Staphylococcus aureus.

Abstract: In this study, pristine graphene/silver/molybdenum disulphide (G/Ag/MoS₂) and reduced graphene oxide/silver/molybdenum disulphide (rGO/Ag/MoS₂) composites materials were prepared via green solvothermal synthesis method and evaluated as supercapacitor electrodes. The morphology and structure of composites were examined by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy. SEM and TEM indicate successful reduction of silver nitrate (AgNO₃) to spherical Ag nanoparticles (NPs) by sodium citrate. The Ag NPs were observed to be evenly deposited on sheets of rGO and MoS₂. From the XPS analysis, the spherical Ag NPs exist in zero-valent state, reflecting successful reduction. Based on cyclic voltammetry (CV) performed under 50 mV/s scan rate, G/Ag/MoS₂ ternary composite exhibits the highest specific capacitance of 56.38 F/g which is 31 % and 29 % enhancement in specific capacitance of rGO/Ag/MoS₂ ternary composite and Ag/MoS₂ binary composite, respectively. It is believed that the presence of graphene may provide conductive pathway and a larger surface area for the distribution of Ag NPs.

Abstract: Single-layer graphene-ZnO hollow sphere (SLG-ZnO(HS)) composites were successfully prepared through facile one-step solvothermal synthesis route. The morphological structures of the samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Hollow spheres consisting of ZnO nanoparticles with a diameter of approximately 30 nm are decorated to both sides of the SLG sheets. The electrochemical performances were tested by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance (EIS). The SLG-ZnO(HS) composite electrode synthesized at a concentration of 0.25 mM Zn precursor exhibited an enhanced specific capacitance of 34.7 F/g at a scan rate of 1 mV/s with energy and power densities of 5.39 W h/kg and 1.73 kW/kg, respectively.

Abstract: The W18O49 nanoparticles were synthesized by solvothermal method with tungsten chloride as raw material and n-propanol as solvent. Polyethylene glycol 400 (PEG-400) was modified for W18O49 nanoparticles (W18O49@PEG). The structure and morphology of W18O49 and W18O49@PEG were characterized by XRD and SEM. Methylene blue aqueous solution was used as wastewater adsorption model. And the comparative experiments with other absorbent materials, such as artificial zeolite and activated carbon were also conducted. The results revealed that after modifying by PEG-400, W18O49 has a better adsorption performance than other materials due to its large specific surface area and high surface energy. Finally adsorption circulation experiment was performed，the results indicate that the W18O49@PEG nanoparticles show great potential in the treatment of colored wastewater.

Abstract: In this work, aluminum-doped ZnO (AZO) is synthesized for heat-shielding applications. A family of ethanolamine (EA: monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine TEA)) is used to control the morphology of aluminum-doped ZnO (AZO) synthesized via a simple solvothermal method at the temperature of 120°C for 6 h. The samples were characterized by field-emission scanning electron microscopy (FE-SEM). The formation of primary ZnO nanoparticles (NPs) showed that TEA yielded highly packed-spherical aggregates not found when DEA and MEA were used. X-ray diffraction (XRD) found that all AZO samples have peaks of the ZnO hexagonal wurtzite structure. XRD patterns of aluminum were found for >10 mol%. UV-Vis-NIR spectrophotometer was used to study the optical property and heat-shielding of the near-infrared region (NIR, the wavelength from 700 - 2500 nm). All AZO NPs of 0, 2, 4, and 10 mol% exhibited strong NIR shielding ability up to 80% insulation. From these results, the AZO NPs have potential use as NIR shielding materials of low-cost and simple processes to be coated on an energy-efficient window as smart window coating in buildings and automotive thus reducing energy consumption, especially in air conditioning usage.

Abstract: The objective of this research was to prepare multi–phase bismuth vanadate (BiVO₄) powder using the solvothermal method to be used as a photocatalyst. In the preparation step, bismuth nitrate and ammonium vanadate were used as the precursors with a mole ratio of 1:1. The mixed solution was diluted to 0.025 M with acetic acid and heated at 200 °C for 2 h in a Teflon–lined stainless steel autoclave vessel. Multi–phase BiVO₄ was obtained without calcination step. Multi–phase BiVO₄ was characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR), and energy dispersive spectroscopy (EDS). The efficiency of multi–phase BiVO₄ for photocatalytic degradation of the mixed dye of methylene blue (MB) and rhodamine B (RhB) solution under UV light irradiation was studied. The concentration of the mixed dye solution was measured by UV–Vis spectrophotometry (UV–Vis). The effect of concentration of catalyst and pH of solution was studied. The optimum conditions for photocatalytic degradation of mixed dye solution were obtained at 0.8 g/L for concentration of multi–phase BiVO₄ and 7.78 for initial pH of the mixed dye solution.

Abstract: Cu₂SnS₃ flower-like nanoparticles consisted of nanoflakes were successfully produced using solvothermal technique at 120°C for 12 h. The precursors used in this process were CuCl₂.2H₂O, SnCl₂.2H₂O, and thiourea with dimethyl sulfoxide (DMSO) as a solvent. The results showed that the as-obtained product was triclinic Cu₂SnS₃ with secondary phases CuS and SnS, and after annealing process, a pure triclinic was obtained. The crystal structure of the obtained samples was investigated by X-ray diffraction which assured the obtained data and the average crystallite size of as-prepared and annealed CTS was found to be 18.42 and 31.6 nm, respectively. Scanning electron microscopy (SEM) showed that the surface morphology has the shape of flower like consisted of nanoflakes. The transmission electron microscope (TEM) displayed the formation of sheets. The band gap was measured using UV-Vis absorption spectroscopy and found that the as-prepared sample has 1.97 eV band gap, which obtained for various phases CuS and SnS. However, this band was changed to 1.26 eV upon the heat treatment at 500°C for 10 minutes. This value of E_g is comparable with the value reported by other literatures.

Abstract: We synthesized TiO₂ nanoparticles dispersed hydroxyapatite (TiO₂-modifed HAp) by solvothermal treatment of α-tricalcium phosphate (α-TCP) using water-isopropanol solution including tetraisopropyl orthotitanate (TTIP). Rod-shaped HAp with TiO₂ nanoparticles were formed by solvothermal treatment. HAp formation decreased with increasing the isopropanol fraction in the solution with TTIP. With increasing the treatment period, the rate of HAp formation in sample increased. The aspect ratio of HAp decreased with increasing the isopropanol fraction in the solution. Synthesized TiO₂-modifed HAp samples shows the photocatalytic decoloration of methylene blue under UV irradiation.

Abstract: The materials currently used in proton-exchange membrane fuel cells (PEMFCs) require complex control of operating conditions to make them sufficiently durable to permit commercial deployment. One of the major materials challenges to allow simplification of fuel cell operating strategies is the discovery of catalyst supports that are much more stable to oxidative decomposition than currently used carbon blacks. Here, we report the synthesis and characterization of advanced nanostructure Ti_0.7W_0.3O₂ prepared via a low-temperature solvothermal process without using any surfactants or stabilizers. A promising doped metal oxide is a candidate for such a durable catalyst support. The synthesized nanoparticles were characterized by XRD, TEM measurements. Results show that Ti_0.7W_0.3O₂ exists in a single-phase solid solution with anatase phase of TiO₂. Interestingly, the average particles size approximately 5 nm that could be promised to have a large specific surface area, which is an extremely important factor for promising catalyst support. Moreover, Ti_0.7W_0.3O₂ synthesized at 200 °C for 6 hours obtains the smaller particles size without particles agglomeration compared to previous researches. These results open a new approach for synthesis nanostructure Ti_0.7W_0.3O₂ by a solvothermal process for further application as catalyst support in PEMFCs.