Showing papers on "Fourier transform infrared spectroscopy published in 2014"
TL;DR: In this paper, the g-C3N4/Ag3VO4 hybrid photocatalysts were prepared by Ag3VO 4 anchoring on the surface of g-c3n4/c3v4.
Abstract: The g-C3N4/Ag3VO4 hybrid photocatalysts were prepared by Ag3VO4 anchoring on the surface of g-C3N4. The transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photo-electron spectroscopy analyses demonstrated that Ag3VO4 nanoparticles well distributed on the surface of g-C3N4 and the g-C3N4/Ag3VO4 hetero-junctions were formed. Compared with pure g-C3N4 and Ag3VO4, the g-C3N4/Ag3VO4 hybrid materials displayed much higher photocatalytic activity for basic fuchsin degradation (20 mg/L, 50 mL) under visible-light irradiation. The 40 wt% g-C3N4/Ag3VO4 photocatalyst exhibited optimal removal rate constant of 0.92 h−1, which was 11.5 and 6.6 times higher than that of pure g-C3N4 and Ag3VO4, respectively. Density functional theory calculations indicated that complementary conduction and valence band-edge hybridization between g-C3N4 and Ag3VO4 could apparently increase separation efficiency of electron-hole pairs of g-C3N4/Ag3VO4 composites, which was confirmed by photoluminescence spectra. In addition, it was found that h+ and •O2−1generated in the photocatalytic process played a key role in basic fuchsin degradation.
530 citations
TL;DR: An innovative and green strategy to synthesize carbon dots (CDs) with a quantum yield (QY) of nearly 19.8% has been successfully established for the first time and the CDs obtained here exhibited various advantages including high fluorescent QY, excellent photostability, non-toxicity and satisfactory stability.
355 citations
TL;DR: A facile bottom-up hydrothermal route for the synthesis of photoluminescent MoS2 quantum dots (QDs) by using sodium molybdate and cysteine as precursors is presented and the high sensitivity for 2,4,6-trinitrophenol (TNP) very likely originated from a combination of the PL resonance energy transfer, electronic energy transfer and electrostatic interactions.
Abstract: Transition metal chalcogenides, especially molybdenum disulfide (MoS2), have recently attracted wide attention from researchers as graphene-analogous materials. However, until now, little literature has reported the synthesis of photoluminescent MoS2 materials and their applications in analytical chemistry. We herein presented a facile bottom-up hydrothermal route for the synthesis of photoluminescent MoS2 quantum dots (QDs) by using sodium molybdate and cysteine as precursors. The prepared MoS2 QDs were characterized by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and UV–vis spectroscopy. The MoS2 QDs were then used as photoluminescent probes to construct a photoluminescence (PL) quenching sensor for detection of 2,4,6-trinitrophenol (TNP). The TNP sensor presented a wide linear range from 0.099 to 36.5 μM with a high detection limit of 95 nM. Furthermore, the sensor displayed a high s...
339 citations
TL;DR: Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopic suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interfacial electron transfer between TiO2 and g-C3N4 of the g-N4/TiO2 composite film.
336 citations
30 Jan 2014
TL;DR: In this paper, the photocatalytic properties of the functional TiO2 and carbon nanocomposite were tested via the decomposition of an organic pollutant, and the catalytic activity of the covalently functionalized nanocomposition was found to be significantly enhanced in comparison to unfunctionalized composite and pristineTiO2 due to the synergistic effect of nanostructured TiO 2 and amorphous carbon bound via covalent bonds.
Abstract: TiO2 nanofibers (30–50 nm diameter), fabricated by the electro-spinning process, were modified with organo-silane agents via a coupling reaction and were grafted with carbohydrate molecules. The mixture was carbonized to produce a uniform coating of amorphous carbon on the surface of the TiO2 nanofibers. The TiO2@C nanofibers were characterized by high resolution electron microscopy (HRTEM), x-ray diffraction (XRD), x-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy. The photocatalytic property of the functional TiO2 and carbon nanocomposite was tested via the decomposition of an organic pollutant. The catalytic activity of the covalently functionalized nanocomposite was found to be significantly enhanced in comparison to unfunctionalized composite and pristine TiO2 due to the synergistic effect of nanostructured TiO2 and amorphous carbon bound via covalent bonds. The improvement in performance is due to bandgap modification in the 1D co-axial nanostructure where the anatase phase is bound by nano-carbon, providing a large surface to volume ratio within a confined space. The superior photocatalytic performance and recyclability of 1D TiO2@C nanofiber composites for water purification were established through dye degradation experiments.
321 citations
TL;DR: In this article, the structure and properties of poly (lactic-co-glycolic acid) copolymers synthesized by ring-opening polymerization of DL-lactide and glicolide were characterized using 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared spectrograph and differential scanning calorimetry.
Abstract: Poly (lactic-co-glycolic acid) (PLGA) is one of the most effective biodegradable polymeric nanoparticles (NPs). It has been approved by the US FDA to use in drug delivery systems due to controlled and sustained- release properties, low toxicity, and biocompatibility with tissue and cells. In the present review, the structure and properties of PLGA copolymers synthesized by ring-opening polymerization of DL-lactide and glicolide were characterized using 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared spectroscopy and differential scanning calorimetry. Methods of preparation and characterization, various surface modifications, encapsulation of diverse anticancer drugs, active or passive tumor targeting and different release mechanisms of PLGA nanoparticles are discussed. Increasing experience in the application of PLGA nanoparticles has provided a promising future for use of these nanoparticles in cancer treatment, with high efficacy and few side effects.
310 citations
TL;DR: In this paper, reduced graphene oxide (rGO) reinforced hydroxyapatite nano-tube (nHA) composites were synthesized in situ using a simple hydrothermal method in a mixed solvent system of ethylene glycol (EG), N, N-dimethylformamide (DMF) and water, without using any of the typical reducing agents.
286 citations
TL;DR: In this paper, a solvothermal method was employed to prepare a novel magnetic composite adsorbent composed of graphene, multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles.
284 citations
TL;DR: In this article, a simple and green method for the synthesis of l-tyrosine-stabilized silver and gold nanoparticles in aqueous medium under ambient sunlight irradiation was reported.
Abstract: In this study, we report a simple and green method for the synthesis of l-tyrosine-stabilized silver (AgNPs) and gold nanoparticles (AuNPs) in aqueous medium under ambient sunlight irradiation. The nanoparticles (NPs) are characterized by UV–visible spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and dynamic light scattering (DLS) techniques. The size and shape of the metal NPs could be controlled by changing the concentration of the substrate, metal precursors, and pH of the medium. The synthesized AgNPs are found to be highly sensitive to Hg2+ and Mn2+ ions with the detection limit for both ions as low as 16 nM under optimized conditions. However AuNPs are found to be sensitive to Hg2+ and Pb2+ ions with a detection limit as low as 53 and 16 nM, respectively. The proposed method was found to be useful for colorimetric detection of heavy metal ions in aqueous medium.
282 citations
TL;DR: Through rational variation in the surface moieties it is demonstrated that the photoluminescence of Si-NCs can be effectively tuned across the entire visible spectral region without changing particle size.
Abstract: The syntheses of colloidal silicon nanocrystals (Si-NCs) with dimensions in the 3–4 nm size regime as well as effective methodologies for their functionalization with alkyl, amine, phosphine, and acetal functional groups are reported. Through rational variation in the surface moieties we demonstrate that the photoluminescence of Si-NCs can be effectively tuned across the entire visible spectral region without changing particle size. The surface-state dependent emission exhibited short-lived excited-states and higher relative photoluminescence quantum yields compared to Si-NCs of equivalent size exhibiting emission originating from the band gap transition. The Si-NCs were exhaustively characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transformed infrared spectroscopy (FTIR), and their optical properties were thoroughly investigated using fluorescence spectroscopy, excited-state lifetime measurements, photobleaching experiments, and solvatochromi...
275 citations
TL;DR: In this article, a series of batch adsorption experiments were conducted to study the effect of pH, dose of adsorbent, metal concentration and temperature on Hg(II) uptake by the functionalized MWCNTs.
TL;DR: In this article, a facile vapor diffusion method in combination with calcination at 550 °C was used to synthesize novel CoFe2O4 hollow sphere/graphene composites.
Abstract: Novel CoFe2O4 hollow sphere/graphene composites were synthesized by a facile vapor diffusion method in combination with calcination at 550 °C. The structure and morphology of as-prepared hybrid materials were characterized by electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Uniform CoFe2O4 hollow spheres with a diameter of about 500 nm and a shell thickness of approximately 50 nm were homogeneously distributed on graphene sheets. The electromagnetic parameters were measured using a vector network analyzer. A minimum reflection loss of −18.5 dB was observed at 12.9 GHz for the CoFe2O4 hollow sphere/graphene composites with a thickness of 2 mm, and the effective absorption frequency ranged from 11.3 to 15.0 GHz. The CoFe2O4 hollow sphere/graphene composites exhibited better microwave absorbing performance than the CoFe2O4 hollow spheres. A possible formation mechanism for CoFe2O4 hollow sphere/graphene composites was proposed.
TL;DR: In this paper, cellulose nanofibrils were extracted from isora fiber by steam explosion method and the results showed that the prepared cellulose fiber showed nanofibers showed high crystallinity (90%) and good thermal stability.
TL;DR: The as-prepared RGO/ZnIn2S4 nanocomposites show enhanced photocatalytic activity for hydrogen evolution under visible light irradiations and an optimum photocatallytic activity is observed over 1.0 wt % RGO incorporated ZnIn 2S4nanocomposite.
Abstract: Highly reductive RGO (reduced graphene oxide)/ZnIn2S4 nanocomposites with a sheet-on-sheet morphology have been prepared via a facile one-pot solvothermal method in a mixture of N,N-dimethylformamide (DMF) and ethylene glycol (EG) as solvent. A reduction of GO (graphene oxide) to RGO and the formation of ZnIn2S4 nanosheets on highly reductive RGO has been simultaneously achieved. The effect of the solvents on the morphology of final products has been investigated and the formation mechanism was proposed. The as-prepared RGO/ZnIn2S4 nanoscomposites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N2-adsorption BET surface area, UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM). The photocatalytic activity for hydrogen evolution under visible light irradiations over t...
TL;DR: Graphene/Zinc oxide (ZnO) nanocomposite was prepared by in situ reduction of zinc acetate and graphene oxide (GO) during refluxing as mentioned in this paper.
Abstract: Graphene/zinc oxide (ZnO) nanocomposite was prepared by in situ reduction of zinc acetate ((CH3COO)2Zn·2H2O) and graphene oxide (GO) during refluxing. For the structural, morphological and elemental analysis, the synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). Hydrogen sensing properties of synthesized graphene/ZnO nanocomposite have been reported in this paper. For gas sensing properties, thick films of synthesized nanocomposite powder were fabricated on alumina substrate. Sensing results revealed that sensor based on 1.2 wt% graphene/ZnO composite exhibits best sensing response towards 200 ppm of hydrogen gas at an optimum operable temperature of 150 °C among the prepared samples with varying concentrations. Inclusion of graphene into ZnO significantly reduced the optimum operable temperature and increased the sensing response of graphene/ZnO composite towards hydrogen gas. Reported results are based on the change in electrical conductivity of synthesized nanocomposites due to superior electronic conductivity of graphene and the interaction between p-type graphene and n-type zinc oxide.
TL;DR: In this article, a facile fabrication method for the synthesis of magnetic biochar composite (MBC) by using low-cost pine bark waste and CoFe 2 O 4 was demonstrated.
TL;DR: In this paper, the photocatalytic performance of Ti3+ self-doped TiO2 was investigated using a simple one-step calcination method, by using low-cost NaBH4 as the reductant.
Abstract: Ti3+ self-doped TiO2 are successfully prepared via a simple one-step calcination method, by using low-cost NaBH4 as the reductant. The as-prepared samples are characterized by different techniques such as X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared spectroscopy (FTIR). EPR spectra confirm the presence of Ti3+ in the bulk of the samples rather than on the surface, which is the reason for the high photocatalytic performance of the catalyst under visible light irradiation. It is worth noting that the visible light absorption is enhanced after HCl washing, and the photocatalytic activity of Ti3+ self-doped TiO2 is proportional to the concentration of the doped Ti3+. Interestingly, the photocatalytic activity of the catalyst under UV light also increases after HCl washing treatment, which is caused by the increase of BET surface area.
TL;DR: A green approach to biosynthesize selenium nanoparticles (Se-np) using dried Vitis vinifera (raisin) extracts is reported, as inferred from the FTIR spectrum, the presence of highly stable lignin biopolymer on the surface of selenia nanoballs suggests a possible role as capping agent.
Abstract: Biomolecule-mediated nanoparticle synthesis has recently the gained attention of researchers due to its ecofriendly and non-toxic nature. Metabolites from plant extracts represent a better alternative to chemical methods to fulfill the growing demand for non-hazardous nanoparticle synthesis routes. Selenium and its nanoparticles have an extensive range of applications. Thus, biofabrication of selenium nanoparticles can be potentially useful in various fields. This study reports a green approach to biosynthesize selenium nanoparticles (Se-np) using dried Vitis vinifera (raisin) extracts. The biosynthesized selenium nanoparticles were characterized using transmission electron microscope (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopic images revealed the spherical shape of biosynthesized selenium nanoparticles and a size range of 3-18 nm. Dynamic light scattering also confirmed the average particle size of 8.12 ± 2.5 nm with 0.212 PDI. The crystalline nature of selenium nanoparticles was confirmed by the X-ray diffraction study. Moreover, as inferred from the FTIR spectrum, the presence of highly stable lignin biopolymer on the surface of selenium nanoballs suggests a possible role as capping agent.
TL;DR: Results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap in the degradation of methyl orange under UV irradiation.
TL;DR: PAS-GO had a priority tendency to adsorb Pb, Cu and Fe from a mixed solution of metal ions, especially from a practical industrial effluent, especially in removing Pb(II) ions from water.
TL;DR: In this paper, the photocatalytic activity of graphitic carbon nitride (g-C3N4) is limited by structure defects generated during the calcination process.
Abstract: Graphitic carbon nitride (g-C3N4) is a promising visible-light-responsive photocatalyst for hydrogen generation from water. As we show here, the photocatalytic activity of g-C3N4 is limited by structure defects generated during the calcination process. Specifically we find that the photocatalytic hydrogen production rate from aqueous methanol is inversely related to the calcination temperature (520–640 °C). The highest activity of 0.301 mmol h−1 g−1 is observed for the sample prepared at the lowest processing temperature. Surface photovoltage (SPV) spectroscopy shows that the maximum photovoltage is reduced (from 1.29 V to 0.62 V) as the processing temperature is increased, in accordance with higher defect concentrations and faster electron–hole recombination. The defects also produce additional optical absorption in the visible spectra and cause a red shifted, weakened photoluminescence (PL). Based on the sub-gap signal in the SPV and PL spectra, defect energy levels are +0.97 V and −0.38 V (vs. NHE) in the band gap of the material. According to Fourier transform infrared (FTIR) spectra, the defects are due to amino/imino groups in the g-C3N4 lattice.
TL;DR: In this article, Nanocrystalline hematite iron oxide (α-Fe2O3) and graphitic carbon nitride (g-C3N4) were used as precursors to synthesize composite photocatalysts by a wet impregnation method.
Abstract: Nanocrystalline hematite iron oxide (α-Fe2O3) and graphitic carbon nitride (g-C3N4) were prepared and used as precursors to synthesise α-Fe2O3–g-C3N4 composite photocatalysts of various compositions by a wet impregnation method. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and photoluminescence spectroscopy (PL). The efficiency of the photocatalysts was evaluated by photoelectrochemical measurements and photodegradation of direct red 81 (DR81) as a target textile pollutant under visible light irradiation. The α-Fe2O3–g-C3N4 composites exhibited remarkably improved visible-light induced photocatalytic activity. The composite photocatalysts with optimal α-Fe2O3 content with the highest photocatalytic activity was found to be 2%-α-Fe2O3–g-C3N4. The synergistic enhancement in the photocatalytic degradation of composite photocatalysts might be due to an increase in the visible-light absorption efficiency and rapid photoinduced charge separation. A possible photocatalytic mechanism has been proposed for the photocatalytic activity of α-Fe2O3–g-C3N4 composite photocatalysts.
TL;DR: In this paper, a simple reflux treatment of ZnFe2O4 nanoparticles (NPs) with graphitic C3N4 sheets in methanol at 90 °C was successfully synthesized through a simple refining treatment of NPs.
Abstract: Magnetic ZnFe2O4–C3N4 hybrids were successfully synthesized through a simple reflux treatment of ZnFe2O4 nanoparticles (NPs) (ca. 19.1 nm) with graphitic C3N4 sheets in methanol at 90 °C, and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. Also, the catalytic activities of heterogeneous ZnFe2O4–C3N4 catalysts were evaluated in photo-Fenton discoloration toward Orange II using H2O2 as an oxidant under visible light (λ > 420 nm) irradiation. The reaction kinetics, degradation mechanism, and catalyst stability, as well as the roles of ZnFe2O4 and C3N4 in photoreaction, were comprehensively studied. It was found that the ZnFe2O4–C3N4 photocatalysts presented remarkable catalytic ability at neutral conditions, which is a great advantage over the traditional Fenton system (Fe2+/H2O2). The ZnFe2O4–C3N4 hy...
TL;DR: In this paper, four activated carbon (AC) samples prepared from rice husk under different activation temperatures have been characterized by N 2 adsorption-desorption isotherms, thermogravimetric analysis (TGA-DTA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).
TL;DR: In this paper, a simple and low-cost electrochemical codeposition method has been introduced to fabricate poly-pyrrole/graphene oxide (PPy/GO) nanocomposites and the areal capacitance of conducting polymer/GO composites is reported for the first time.
TL;DR: In this article, a positively charged composite nanofiltration membranes were facilely prepared by polydopamine (PDA) deposition followed by poly(ethylene imine) (PEI) grafting on polyethersulfone (PES) substrates.
TL;DR: It was found that when cellulose is dissolved in DMAc/LiCl cosolvent system, the hydroxyl protons of cellulose form strong hydrogen bonds with the Cl(-), during which the intermolecular hydrogen bonding networks of cellulOSE is broken with simultaneous splitting of the Li(+)-Cl(-) ion pairs.
Abstract: Understanding the interactions between solvent molecules and cellulose at a molecular level is still not fully achieved in cellulose/N,N-dimethylacetamide (DMAc)/LiCl system. In this paper, cellobiose was used as the model compound of cellulose to investigate the interactions in cellulose/DMAc/LiCl solution by using Fourier transform infrared spectroscopy (FTIR), 13C, 35Cl, and 7Li nuclear magnetic resonance (NMR) spectroscopy and conductivity measurements. It was found that when cellulose is dissolved in DMAc/LiCl cosolvent system, the hydroxyl protons of cellulose form strong hydrogen bonds with the Cl–, during which the intermolecular hydrogen bonding networks of cellulose is broken with simultaneous splitting of the Li+–Cl– ion pairs. Simultaneously, the Li+ cations are further solvated by free DMAc molecules, which accompany the hydrogen-bonded Cl– to meet electric balance. Thereafter, the cellulose chains are dispersed in molecular level in the solvent system to form homogeneous solution. This work ...
TL;DR: Iron-based nanoparticles synthesized using oolong tea extracts demonstrated that kinetics fitted well to the pseudo first-order reaction by removing 75.5% of MG, indicating that OT-FeNP has the potential to serve as a green nanomaterial for environmental remediation.
TL;DR: The cytotoxicity study revealed that the C-dots did not cause any toxicity to cells at a concentration as high as 20 mg/mL, which suggested that theC-d dots present in commercial coffee may have more potential biological applications.
TL;DR: This work fabricated a facile and environmentally friendly composite via direct assembly of surface passivated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (LDH).
Abstract: It would be of significance to design a green composite for efficient removal of contaminants. Herein, we fabricated a facile and environmentally friendly composite via direct assembly of surface passivated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (LDH). The resulting LDH–carbon dot composites were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and N2 adsorption–desorption technique. The adsorption performances of the resulting LDH–carbon dot composites were evaluated for the removal of anionic methyl blue dye. Taking advantage of the combined benefits of LDH and carbon dots, the as-prepared composites exhibited high uptake capability of methyl blue (185 mg/g). The adsorption behavior of this new adsorbent fitted well with Langmuir isotherm and the pseudo-second-order kinetic model. ...