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Showing papers in "New Journal of Chemistry in 2019"


Journal ArticleDOI
TL;DR: In this article, a carbon paste electrode modified with CuO nanoparticles and n-hexyl-3methylimidazolium hexafluorophosphate (CPE/CuO-NPs/HMIPF6) was used for the analysis of epinine for the first time.
Abstract: This study suggests a carbon paste electrode modified with CuO nanoparticles and n-hexyl-3-methylimidazolium hexafluorophosphate (CPE/CuO-NPs/HMIPF6) as a powerful tool for the analysis of epinine for the first time. It has been confirmed that CPE/CuO-NPs/HMIPF6 can improve the sensitivity of epinine electro-oxidation and reduce the overvoltage of this drug compared to an unmodified electrode. The CuO nanoparticles are characterized by XRD and TEM methods. The CPE/CuO-NPs/HMIPF6 exhibited a detection limit of 0.2 μM and a dynamic range of 0.7–900 μM for analysis of epinine by the square wave voltammetric method. Epinine determination was performed successfully by CPE/CuO-NPs/HMIPF6 in serum and urine samples.

208 citations


Journal ArticleDOI
TL;DR: In this article, the NBBSH/GCE sensor exhibited enhanced sensing performances such as sensitivity, limit of detection (LOD), linear dynamic range (LDR), and long-term stability towards selective arsenic ions.
Abstract: (E)-N′-(2-Nitrobenzylidene)-benzenesulfonohydrazide (NBBSH) was prepared from 2-nitrobenzaldehyde and benzenesulfonylhydrazine by using a simple condensation process with medium yield. It was then crystallized in methanol and characterized using various spectroscopic techniques such as Fourier transform infra-red spectroscopy (FTIR), ultra-violet visible spectroscopy (UV-vis), proton nuclear magnetic resonance (1H-NMR), X-ray photoelectron spectroscopy (XPS), and carbon-13 nuclear magnetic resonance (13C-NMR). The structure of the NBBSH molecule was confirmed using the single crystal X-ray diffraction technique (SCXRDT). A thin layer of NBBSH slurry was deposited onto a cleaned and dried flat round surface of GCE with a binding agent (Nafion) to fabricate a sensitive and selective heavy metal ion (HMI) sensor. The fabricated NBBSH/GCE sensor exhibited enhanced sensing performances such as sensitivity, limit of detection (LOD), linear dynamic range (LDR), and long-term stability towards selective arsenic ions. The calibration curve (CC) was found to be linear over a broad range of As3+ conc. (0.1 nM–0.1 M) and the calculated sensitivity and LOD (based on 3N/S) were found to be ∼190.0 pA μM−1 cm−2 and 50.0 pM, respectively. This novel approach can be used as an efficient path for the development of HMI sensors regarding monitoring of hazardous materials in biological and environmental sciences.

145 citations


Journal ArticleDOI
TL;DR: Using one-step wet-chemically synthesized ternary ZnO/CuO/Co3O4 nanoparticles (NPs), a sensitive chemical sensor was developed to detect melamine selectively using an electrochemical approach in a phosphate buffer solution.
Abstract: Using one-step wet-chemically synthesized ternary ZnO/CuO/Co3O4 nanoparticles (NPs), a sensitive chemical sensor was developed to detect melamine selectively using an electrochemical approach in a phosphate buffer solution. The calcined ZnO/CuO/Co3O4 NPs were investigated using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), ultraviolet visible spectroscopy (UV-vis), and Fourier-transform infrared spectroscopy (FTIR). To fabricate the melamine sensor, a slurry of NPs in ethanol was deposited as a uniform thin layer on a glassy carbon electrode (GCE). The calibration curve of the proposed melamine sensor in the form of current versus concentration (in logarithmic scale) plot is found to be linear over a melamine concentration range of 0.05 nM–0.05 mM. The sensitivity of the sensor is very good (36.98 μA μM−1 cm−2) and the detection limit is very low (9.7 ± 0.5 pM). The melamine sensor with active ZnO/CuO/Co3O4 NPs shows good reliability, precise reproducibility and a short response time in sensing performances. The developed ternary metal oxide nanoparticle based sensor is a new introduction in sensor technology for determining melamine in environmental samples reliably.

140 citations


Journal ArticleDOI
TL;DR: In this paper, a uric acid (UA) sensor was fabricated using a wet-chemical (co-precipitation) method to prepare doped ZnO/Ag2O/Co3O4 nanoparticles and load them onto a glassy carbon electrode (GCE) by an electrochemical approach.
Abstract: A highly sensitive uric acid (UA) sensor was fabricated using a wet-chemical (co-precipitation) method to prepare doped ZnO/Ag2O/Co3O4 nanoparticles (NPs) and load them onto a glassy carbon electrode (GCE) by an electrochemical approach. The detailed characterization of the NPs was performed by using conventional methods, such as X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-vis.), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Tunneling electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) analysis. Thermal gravimetric analysis (TGA) of the as-prepared ternary NPs was performed in order to study the stability of NPs in different temperature ranges over which the weight loss and thermal effect are significant. During the electrochemical analysis, the proposed UA sensor was found to be linear over a large linear dynamic range (LRD; 0.1 nM–0.01 mM). The analytical performance of the sensor such as sensitivity (82.3323 μA μM−1 cm−2) was estimated from the slope of the calibration curve and the detection limit (89.14 ± 4.46 pM) was calculated at a signal to noise ratio of 3. The proposed UA biosensor showed reliable reproducibility, a short response time (22.0 s), long-term stability, and no interference effects. The ZnO/Ag2O/Co3O4 NPs/GCE sensor was also validated with real biological samples. Thus, this method might be a prospective and reliable method for the future development of enzyme-free biosensors using doped ternary metal oxides in broad scales.

136 citations


Journal ArticleDOI
TL;DR: In this article, a 3-methoxyaniline (3-MA) sensor based on Ag2O@La2O3 nanosheets/Nafion/GCE was presented.
Abstract: Herein, a facile wet chemical method was used to synthesize doped semiconductor Ag2O@La2O3 nanosheets (NSs) in an alkaline medium. Characterization tools such as ultraviolet/visible spectroscopy (UV/vis), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) in addition to field emission scanning electron microscopy (FESEM) equipped with X-ray energy-dispersive spectroscopy (EDS) were used for the optical, elemental, morphological, and structural characterizations of Ag2O@La2O3 NSs. A glassy carbon electrode (GCE) was modified by the fabrication of a thin layer of Ag2O@La2O3 NSs with 5% ethanolic Nafion as a conducting binder onto its flat surface for the development of a selective as well as ultra-sensitive 3-methoxyaniline (3-MA) electrochemical sensor. A simple electrochemical technique was used for the first time to detect 3-MA via an electrochemical approach using newly designed Ag2O@La2O3 NSs/Nafion/GCE as a selective 3-MA electrochemical sensor in an aqueous system. Thus, electrochemical responses along with higher sensitivity, a large dynamic range and long-term stability towards 3-MA were observed by this electrochemical approach. The calibration curve was found to be linear over a wide linear dynamic range (LDR) of 3-MA concentrations (0.1 nM to 0.1 mM). The limit of detection (LOD) at a signal-to-noise ratio of 3 (S/N = 3), limit of quantification (LOQ) and sensitivity were found to be 0.085 ± 0.002 nM, 0.28 ± 0.02 nM and 0.0110 μA μM−1 cm−2, respectively, from the gradient of the calibration plot. Hence, this is a new and well-organized way for the development of a 3-MA electrochemical sensor based on Ag2O@La2O3 NS-modified GCE, and it can be applied in real sample analysis for the safety of the natural environment. To the best of our knowledge, this report is the first study on the development of a highly sensitive 3-MA sensor based on Ag2O@La2O3 NSs/Nafion/GCE using a reliable electrochemical technique.

128 citations


Journal ArticleDOI
TL;DR: One homo-trinuclear 3D and five novel windmill-type hetero-pentanuclear 3d-4f complexes were synthesized by the reactions of a new bis(Salamo)-based tetraoxime ligand (H4L) with Zn(OAc)2·2H2O and Ln(NO3)3·6H 2O (Ln = Sm, Eu, Gd, Tb and Dy), respectively as discussed by the authors.
Abstract: One homo-trinuclear 3d and five novel windmill-type hetero-pentanuclear 3d-4f complexes [Zn3(L)(OAc)2(H2O)]·CH2Cl2 (1), [Zn4(L)2Sm(NO3)2(EtOH)2]NO3·H2O·2CHCl3 (2), [Zn4(L)2Eu(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (3), [Zn4(L)2Gd(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (4), [Zn4(L)2Tb(NO3)2(EtOH)2]NO3·C2H5OH (5) and [Zn4(L)2Dy(NO3)2(EtOH)2]NO3·C2H5OH·2CHCl3 (6) were synthesized by the reactions of a new bis(Salamo)-based tetraoxime ligand (H4L) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O (Ln = Sm, Eu, Gd, Tb and Dy), respectively. The structures of complexes 1–6 were characterized via elemental analyses, FT-IR spectroscopy, UV-Vis spectroscopy and single crystal X-ray crystallography, and their fluorescence properties, catalytic activities and Hirshfeld surface analyses were studied.

105 citations


Journal ArticleDOI
Xiao-Yu Guo1, Zhen-Peng Dong1, Fei Zhao1, Zhiliang Liu1, Yan-Qin Wang1 
TL;DR: A 2D zinc-II metal-organic framework (Zn-MOF-1) formulated as [Zn2(L)2(TPA)]·2H2O, (L = 4-(tetrazol-5-yl)phenyl-4,2′:6′,4′′-terpyridine, TPA = terephthalic acid) was successfully obtained under solvothermal conditions as mentioned in this paper.
Abstract: A 2D zinc(II) metal–organic framework (Zn-MOF-1) formulated as [Zn2(L)2(TPA)]·2H2O, (L = 4-(tetrazol-5-yl)phenyl-4,2′:6′,4′′-terpyridine, TPA = terephthalic acid) was successfully obtained under solvothermal conditions. Zn-MOF-1 shows a new 2D double-layered honeycomb structure containing Zn2+ ions, ligand L and TPA, with uncoordinated nitrogen atoms (from pyridine rings and tetrazol rings) of L and uncoordinated carboxylate oxygen atoms of TPA, which easily form hydrogen bonds with analytes. Fluorescence analysis reveals that Zn-MOF-1 generates strong blue luminescence, which can be assigned to ligand-centered emission. More importantly, it is the first reported recyclable multi-responsive Zn-MOF fluorescence sensor for pesticide 2,6-dichloro-4-nitroaniline, Fe(III) and Cr(VI) (CrO42−/Cr2O72− ions) detection with high sensitivity, selectivity and low detection limit in methanol or water via fluorescence quenching. Furthermore, selective sensing by Zn-MOF-1 of 2,6-dichloro-4-nitroaniline, Fe3+ ions, and CrO42− or Cr2O72− ions can mainly be attributed to the absorption by the analytes of the excitation and/or emission light of Zn-MOF-1 and the electronic interactions between Zn-MOF-1 and the analytes.

103 citations


Journal ArticleDOI
TL;DR: In this article, a functional nanoarchitecture has been designed allowing us to generate a layered tablet with a chitosan/halloysite nanocomposite film sandwiched between two alginate layers.
Abstract: We have prepared new biohybrid materials based on halloysite nanotubes and natural polymers (alginate and chitosan) for the controlled and sustained release of bioactive species. A functional nanoarchitecture has been designed allowing us to generate a layered tablet with a chitosan/halloysite nanocomposite film sandwiched between two alginate layers. The assembly of the raw components and the final structure of the hybrid tablet have been highlighted by the morphological and wettability properties of the prepared materials. Since the biohybrid has been designed as a smart carrier, halloysite nanotubes have been first loaded with a model drug (sodium diclofenac). The effect of the tablet thickness on the drug release kinetics has been investigated, confirming that the delivery capacity can be controlled by modifying the alginate amounts of the external layers. A simulation of the typical pH conditions along the human gastro-intestinal path has been carried out. Strong acidic conditions (pH = 3, typical in the stomach) prevent the drug release. In contrast, the drug was released at pH = 5.7 and 7.8, which simulate the duodenum/ileum and colon paths, respectively. These results demonstrate that the proposed nanoarchitecture is suitable as a functional material with tunable delivery capacity.

102 citations


Journal ArticleDOI
TL;DR: In this article, porous graphitic carbon nitrides (g-C3N4) were synthesized via a one-step pyrolysis process using different low-cost, environmentally benign, nitrogen-rich organic precursors, namely, urea, thiourea, and melamine.
Abstract: Herein, porous graphitic carbon nitrides (g-C3N4) were synthesized via a one-step pyrolysis process using different low-cost, environmentally benign, nitrogen-rich organic precursors, namely, urea, thiourea, and melamine. The physicochemical and photophysical properties of the obtained g-C3N4 samples were characterized by X-ray diffraction (XRD), solid-state MAS NMR, X-ray photoelectron microscopy (XPS), transmission electron microscopy (TEM), N2 adsorption/desorption, thermogravimetric analysis (TGA), UV-Vis diffuse reflectance absorption spectra (DRS), photoluminescence and electrochemical measurements. This study shows that the photocatalytic hydrogen evolution under visible light is around five times higher if urea is used as the g-C3N4 precursor instead of thiourea or melamine. This finding is confirmed by the lower degree of polymerization of the g-C3N4 sample formed from urea, leading to an altered porous structure, higher pore volume, and enhanced surface area. Moreover, the resulting structural imperfections lead to slightly more active sites as indicated by the most negative conduction band potential in urea-based g-C3N4.

97 citations


Journal ArticleDOI
TL;DR: In this paper, diethylenetriamine functionalized graphene oxide (DETA-GO) has been synthesized and its corrosion inhibition performance was evaluated in 1 M HCl for mild steel.
Abstract: In the present work diethylenetriamine functionalized graphene oxide (DETA-GO) has been synthesized and its corrosion inhibition performance was evaluated in 1 M HCl for mild steel. The chemical structure of the synthesized DETA-GO was analyzed by FTIR and the morphology was studied using SEM, TEM, and FTIR. The corrosion inhibition behavior was studied using weight loss studies, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. DETA-GO behaved as an efficient corrosion inhibitor as evident from the results of the electrochemical analysis. Electrochemical studies showed that the inhibition efficiency of DETA-GO increased with the concentration and reached 92.67% at a concentration of 25 mg L−1. The inhibitor exhibits a mixed type nature with cathodic predominance. The protective film of the inhibitor over the mild steel surface was examined by SEM and FTIR-ATR studies. A computational study using DFT further supports the promising corrosion inhibition behavior of DETA-GO.

87 citations


Journal ArticleDOI
TL;DR: In this article, N and P co-doped red emissive carbon dots (R-CDs) were firstly prepared with o-phenylenediamine and phosphoric acid as the raw materials using a facile hydrothermal method.
Abstract: Red emissive carbon dots (CDs) have attracted more and more attention in biological fields, due to less interference from autofluorescence of the biological matrix and lower photodamage to biological tissues. Herein, N and P co-doped red emissive carbon dots (R-CDs) were firstly prepared with o-phenylenediamine and phosphoric acid as the raw materials using a facile hydrothermal method. The R-CDs exhibited excitation-independent emission peaks at 622 nm with an absolute fluorescence quantum yield (QY) of 15% in water. At the same time, N-doped yellow emissive carbon dots (Y-CDs) were also synthesized with o-phenylenediamine using a similar procedure to that used for the R-CDs. Both CDs were successfully applied to in vitro cell imaging. By comparing the optical properties and surface states of the Y-CDs and R-CDs, we concluded that the photoluminescence (PL) of the CDs is related to the surface states of both CDs, and the surface functional group CO plays the main role in the yellow emission, while the new surface state introduced by doping phosphorus atoms into the R-CDs is responsible for the red emission. More importantly, the R-CDs had an excellent capability for killing cancer cells and inhibited the growth of a tumor under 532 nm laser irradiation. This work provides a novel strategy for preparing red emissive CDs and expands the application of CDs in biological fields.

Journal ArticleDOI
TL;DR: In this article, a piezoelectric nanogenerator (PNG) was used to harvest biomechanical energy from pulsing mechanical energy by fixing it to fingers on the human palm.
Abstract: Here we demonstrate the mechanical energy harvesting performance of a poly(vinylidene-fluoride) (PVDF) device which is loaded with reduced graphene oxide–silver nanoparticles (rGO–Ag). The current results show that the addition of rGO–Ag enhances the polar beta and gamma piezoelectric phases in PVDF, which is capable of generating a greater piezoelectric output, thereby eliminating the requirement of any external poling process. X-ray diffraction (XRD) and Fourier transform infra-red spectroscopy (FT-IR) characterizations were employed for the identification and quantification of the piezoelectric polar phases of the nanocomposite films. Raman spectroscopy confirmed the interactions between rGO–Ag and PVDF. Polarization vs. electric field (P–E) loop testing was performed and it was found that on the application of an external electric field of 148 kV cm−1 the nanocomposite showed an energy density value of ∼0.26 J cm−1, which indicates its potential for energy storage applications. The fabricated energy harvesting device, a piezoelectric nanogenerator (PNG), could charge up capacitors and light up to 20 commercial blue light-emitting diodes. The PNG was tested to harvest biomechanical energy from pulsing mechanical energy by fixing it to fingers on the human palm. The PNG was also fixed to flip-flops in order to demonstrate its footwear connected energy harvesting application. The PNG showed a peak output open circuit voltage of ∼18 V and a short circuit current of ∼1.05 μA, with a peak power density of 28 W m−3 across a 1 MΩ resistor. The PNG shows a moderate efficiency of 0.65%.

Journal ArticleDOI
TL;DR: The overlap that had been induced between the fluorescence emission spectrum of Hb and the absorption spectrum of drugs is demonstrated, which has proved that there is a high probability to the occurrence of energy transfer from HB and LMF in the absence and presence of NRF.
Abstract: The interaction of hemoglobin (Hb) with lomefloxacin (LMF), in the absence and presence of norfloxacin (NRF) functioning as a binary and ternary system, has been analyzed through the utilization of different spectroscopic and molecular dynamics (MD) simulation techniques. The thermodynamic parameters have been calculated from the fluorescence data that were measured at three different temperatures. Considering the negative values of ΔH0 and ΔS0, it is indicated that the functionalities of van der Waals forces and hydrogen bonds are essential throughout the binding of LMF and NRF to Hb. The fluorescence spectra study of Hb, with regards to the binary and ternary systems, indicated that the fluorescence intensity decreased as a result of the drug enhancement, which proves that the interaction has occurred. The existing distance I between the donor and acceptor was gained using the Forster energy, which was in accordance with the fluorescence resonance energy transfer (FRET) and found to be 2.33 and 2.39 nm for the Hb–LMF and (Hb–NRF) LMF complexes, respectively. These numbers are indicative of the induced complex formation between Hb and the drugs in both systems. The properties of the Tyr and Trp residues were obtained through synchronous fluorescence results, the complex structure of Hb–LMF was observed to be altered in the absence and presence of NRF. The outcomes of circular dichroism (CD) represented the conformational changes of Hb that had occurred upon binding to LMF and NRF as the binary and ternary systems. Moreover, molecular modeling confirmed the experimental results which were obtained with regards to the binding of the Hb–LMF and (Hb–NRF) LMF complexes. The crucial functionality of the polar residues in the stability of the complexes was indicated by the interaction studies of LMF in the binary and ternary systems.

Journal ArticleDOI
TL;DR: In this article, the synthesis of bare TiO2 and various molar concentrations of ruthenium (Ru)-doped nanoparticles by the precipitation method was reported. And the results from the UV-vis spectroscopy clearly indicated a red-shift of the optical response toward the visible region owing to the reduced band gap energy, thus showing an enhancement of the visible spectrum.
Abstract: This paper reports the synthesis of bare TiO2 and various molar concentrations of ruthenium (Ru)-doped TiO2 nanoparticles by the precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), N2 adsorption/desorption techniques, X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), Raman spectroscopy, photoluminescence spectroscopy (PL), and electrochemical measurements. The results from the UV-vis spectroscopy clearly indicated a red-shift of the optical response toward the visible region owing to the reduced band gap energy, thus showing an enhancement of the absorption in the visible spectrum. The XRD study showed that the samples were crystallized with the photoactive anatase phase of TiO2. The microstructural study using Raman spectroscopy indicated that the Ru dopant occupied the substitutional sites in the TiO2 lattice. According to the Mott–Schottky analysis, the flat band potential of the Ru-doped TiO2 was shifted to the negative potential. The photocurrent, electrochemical impedance spectroscopy, and photoluminescence revealed a higher photogenerated charge-carriers separation efficiency of the doped sample. The photocatalytic activities of the bare TiO2 and (0.05–0.2 mol%) Ru-doped TiO2 nanoparticles were examined by studying the hydrogen production from water using methanol as a sacrificial reagent and Pt nanoparticles as a cocatalyst under light of λ ≥ 320. The optimal iron content was determined to be 0.1 mol% and the corresponding hydrogen production rate was 3400 μmol h−1 in aqueous methanol, which is enhanced by more than 2 times compared to bare TiO2 (1500 μmol h−1) under the same reaction conditions. The higher activity for the doped materials was attributed to the presence of the Ru dopant to facilitate the visible-light-driven activity by introducing the electron donor/acceptor level of ruthenium and the mid-band energy level of defects between the conduction band minimum and valence band maximum of TiO2.

Journal ArticleDOI
TL;DR: Iminyl radicals have emerged as versatile synthons for N-heterocycle constructions and ring-opening reactions as mentioned in this paper, and are a special class of N-centered radicals that display unique reactivity, enable H-abstraction to generate more stable carbon radicals, and serve as radical-type electrophiles.
Abstract: Iminyl radicals have emerged as versatile synthons for N-heterocycle constructions and ring-opening reactions. Iminyl radicals are a special class of N-centered radicals that display unique reactivity, enable H-abstraction to generate more stable carbon radicals, and serve as radical-type electrophiles, thus providing opportunities to explore novel transformations.

Journal ArticleDOI
TL;DR: In this article, the degradation efficiency of organic pollutants on a perovskite-type LaFeO3-coupled graphitic carbon nitride (g-C3N4) photocatalyst under visible light irradiation was evaluated.
Abstract: The objective of this paper was to prepare, characterize and evaluate the degradation efficiency of organic pollutants on a perovskite-type LaFeO3-coupled graphitic carbon nitride (g-C3N4) photocatalyst under visible light irradiation. The photocatalyst was synthesized by a simple calcination method. The physical and photophysical properties of the LaFeO3/g-C3N4 composite photocatalyst with various weight ratios of LaFeO3 were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherm measurement, UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and electrochemical measurements. According to the flat band potential estimated by the Mott–Schottky plot and the optical band gap measurements, both semiconductors (LaFeO3 and g-C3N4) can absorb visible light and have band edge positions that allow the transfer of photoelectrons from g-C3N4 to LaFeO3. As compared to g-C3N4, the C 1s and N 1s peaks of the LaFeO3/g-C3N4 composite showed an obvious shift to lower binding energy, implying the existence of a synergistic effect between g-C3N4 and LaFeO3. Furthermore, photocurrent measurement and electrochemical impedance spectroscopy revealed the higher photo-induced charge carrier separation efficiency of the LaFeO3/g-C3N4 composite. The results show that the visible light activity of the composite photocatalyst LaFeO3/g-C3N4 for the degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) is higher than that of pure LaFeO3 and g-C3N4, respectively. However, the main reason for the enhanced activity was attributed to the interfacial transfer of photogenerated electrons and holes between LaFeO3 and g-C3N4, leading to the effective charge separation in the composite, inhibited recombination of electron–hole pairs and, finally, enhanced photocatalytic performance of the composite. It was found that the holes, hydroxyl radicals (•OH) and superoxide radical ions (O2−) are the main reactive species in the degradation reaction of RhB and 4-CP over the LaFeO3/g-C3N4 composite photocatalyst. More importantly, on the basis of the estimated conduction band (CB) from the Mott–Schottky plots, LaFeO3 and the composite show no activity toward hydrogen production under visible light. This work can be applied for the production of other visible-light-responsive photocatalysts based on g-C3N4 that have potential in environmental purification applications.

Journal ArticleDOI
TL;DR: In this article, the authors reported a simple synthesis process for the construction of CuO@ZnO p-n heterojunctions via the in situ deposition of p-type CuO nanoparticles on the surface of three dimensional ZnO.
Abstract: In this work, we report a simple synthesis process for the construction of CuO@ZnO p–n heterojunctions via the in situ deposition of p-type CuO nanoparticles on the surface of three dimensional ZnO. In this study, a CuO@ZnO heterojunction material is obtained via an effective hydrothermal method. At the interface of the CuO@ZnO p–n heterojunctions, due to a difference in Fermi levels and suitable band position, the transfer of electrons and holes across the p–n heterojunction interface can be easily achieved, leading to improved photogenerated charge carrier dynamics. The photocatalyst exhibited high photocatalytic activity and long-term stability towards photochemical hydrogen production and the reduction of a pollutant, methylene blue (MB) dye, in solution. XRD showed the existence of CuO in the sample with the peak at 38.7° corresponding to the (111) plane. XPS analysis also confirmed the presence of a Cu2+ state and the non-existence of metallic Cu and Cu+ states. The photocatalytic activity was evaluated with respect to the liquid-phase degradation of MB at pH values of 3, 7 and 10 under UV-visible light irradiation. The rate of H2 production was high for 20 mg of ZnO and CuO@ZnO under solar irradiation: 2353 and 4604 μmol h−1 g−1, respectively, with the sacrificial reagent Na2S–Na2SO3. This result is competitive with the values obtained with previously reported copper based ZnO photocatalysts for photocatalytic hydrogen production and indicates that further performance improvements could be achieved with an ordered nanostructure morphology. The high photocatalytic H2 production activity is attributed predominantly to the presence of CuO species and the small size of the heterojunction between CuO and ZnO, facilitating interfacial charge carrier transfer from the ZnO nanoparticles. This work reveals the potential of the CuO@ZnO photocatalyst for efficient hydrogen evolution from water splitting and for environmental applications.

Journal ArticleDOI
TL;DR: In this article, the effect of the ZrO2 content on the rate of visible light photocatalytic hydrogen evolution was investigated using platinum as a co-catalyst in methanol containing aqueous solution.
Abstract: Herein, commercially available zirconium dioxide (ZrO2) and lab synthesized graphitic carbon nitride (g-C3N4) composite photocatalysts were prepared by a simple calcination method. The prepared composite photocatalysts with varying wt% of ZrO2 were tested for hydrogen production under visible light. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron microscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, photoluminescence spectroscopy (PL) and electrochemical measurements. The effect of the ZrO2 content on the rate of visible light photocatalytic hydrogen evolution was investigated using platinum as a co-catalyst in methanol containing aqueous solution. The above results show that the synergistic effect existing between ZrO2 and C3N4 leads to efficient photogenerated charge carrier separation and consequently improves visible light hydrogen production of the composites. The optimal ZrO2 content is determined to be 5% displaying 10 times higher activity than pure ZrO2. The higher activity of the composite materials was attributed to the efficient charge separation through well-developed interfacial connection between ZrO2 and g-C3N4. The efficient charge transfer and separation, as well as the suppressed recombination of photogenerated electron–hole pairs, were verified by photoluminescence (PL) emission spectroscopy, transient photocurrent measurements and electrochemical impedance spectroscopy (EIS). On the basis of the measured conduction band (CB) from Mott–Schottky plots and optical band gaps, the valence band (VB) was estimated for the composite semiconductors and the photocatalytic mechanism was also discussed.

Journal ArticleDOI
TL;DR: An amine-functionalized glucose namely hexamethylene-1,6-bis(N-D-glucopyranosylamine) (HGA) was synthesized and characterized as discussed by the authors.
Abstract: An amine-functionalized glucose namely hexamethylene-1,6-bis(N-D-glucopyranosylamine) (HGA) was synthesized and characterized. The corrosion inhibition behavior of HGA on API X60 steel in 3.5 wt% NaCl saturated with CO2 was evaluated by electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), linear polarization resistance (LPR), potentiodynamic polarization (PDP) and scanning electron microscopy (SEM). The adsorption of HGA on the API X60 mild steel surface obeyed the Langmuir isotherm. The results of potentiodynamic polarization indicated that the HGA molecule behaved as a mixed type inhibitor by reducing both the anodic and the cathodic electrochemical reactions. The maximum corrosion inhibition efficiency obtained was 91.82% at a concentration of 2.27 × 10−4 M (100 ppm). HGA reduced the extent of localized pitting corrosion on the steel surface. The inhibitor is protonated in the system and assumes a parallel orientation during adsorption on the steel. The oxygen and nitrogen atoms serve as reactive centers for adsorption, based on quantum chemical calculations and Monte Carlo simulations in the protonated form.

Journal ArticleDOI
TL;DR: In recent years, metal–organic frameworks have been extensively used as drug carriers due to their benefits and are still being used for this purpose.
Abstract: In recent years, metal–organic frameworks have been extensively used as drug carriers due to their benefits. In the present study, nanoporous UiO-66 metal–organic framework nanoparticles were prepared using the solvothermal method, and samples of these nanoparticles were loaded with the antibiotic drug ciprofloxacin (CIP). The amount of drug loading on the UiO-66 nanoporous metal–organic frameworks was calculated to be 84%. In addition, the drug delivery behavior for CIP was studied, and showed 80% and 87% release within 3 days in phosphate-buffered saline (PBS, pH 7.4) and acetate buffer (AB, pH 5.0) solutions, respectively. Furthermore, the antibiotic activities of ciprofloxacin trapped in the nanopores of the prepared UiO-66 were evaluated using the disk diffusion method on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. In addition, all of the products including UiO-66 and CIP-UiO-66 were completely characterized via Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV/vis) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis and transmission electron microscopy (TEM).

Journal ArticleDOI
Jiong Xu1, Jin Liu1, Zhen Li1, Xianbiao Wang1, Xu Yongfei1, Saisai Chen1, Wang Zhuo1 
TL;DR: In this paper, trimesic acid (BTC), a highly electron-deficient and polar molecule, was used as an organic ligand in order to produce efficient adsorbents for hydrogen gas.
Abstract: Nanostructured Zr(IV) metal organic frameworks (MOFs-808) with high stability are synthesized by using trimesic acid (BTC), a highly electron-deficient and polar molecule, as an organic ligand in order to produce efficient adsorbents for hydrogen gas. The MOFs-808 are characterized by XRD, FT-IR, SEM, TEM, specific surface area measurements and thermogravimetric analysis, and the conditions (e.g., the reactant molar ratio, the amount of solvent, the reaction temperature and the reaction time) for synthesis of MOFs-808 are optimized. The MOF-808 obtained under optimized preparation conditions has higher crystallinity, a larger specific surface area, and relatively high stability both in acidic solution and at temperatures up to 300 °C. The hydrogen storage capacity of the optimized MOF-808 under 4 MPa reaches 7.31 wt% at 77 K, which is close to the ultimate target defined for hydrogen storage. Our results indicate that the presence of the electron-deficient ligand on MOFs-808 favors the adsorption of hydrogen gas.

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TL;DR: Water-soluble carbon quantum dots (CQDs) are synthesized via an acid assisted ultrasonic route using the biomass carbon precursor of potato starch as the raw material.
Abstract: Water-soluble carbon quantum dots (CQDs) are synthesized via an acid assisted ultrasonic route using the biomass carbon precursor of potato starch as the raw material. Results from various characterization methods including TEM, XRD, XPS, Raman spectroscopy and FTIR spectroscopy indicate that monodispersed CQDs with a mean diameter of about 3–5 nm and abundant oxygen-containing groups have been prepared. The photoluminescence performance of the CQDs has been investigated and the results demonstrate that the CQDs exhibit strongly green luminescence, with excitation wavelength-independent, pH-sensitive and ionic strength-dependent luminescence properties. In addition, it has been demonstrated that the CQDs can serve as a very effective fluorescent probe for the selective and sensitive detection of zinc ions in aqueous solution. Hopefully, the synthesized CQDs can find potential applications in pH sensors, bio-imaging, and photocatalysis related areas.

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TL;DR: In this article, a plasmonic silver nanoparticle incorporated reduced graphene oxide and its photocatalytic performance for the selective oxidation of various benzylamines to the corresponding imines using molecular oxygen as an oxidant under ambient temperature conditions.
Abstract: Visible light assisted photocatalytic transformations have been considered as an efficient and sustainable approach for the production of high-value chemicals. The present paper describes the synthesis of plasmonic silver nanoparticle incorporated reduced graphene oxide and its photocatalytic performance for the selective oxidation of various benzylamines to the corresponding imines using molecular oxygen as an oxidant under ambient temperature conditions. The developed photocatalyst was found to be highly stable and exhibited excellent photoactivity with a consistent recycling ability for several runs without a loss in activity. Moreover, to the best of our knowledge, the developed photocatalyst represents the first example of a graphene-based photocatalyst for the oxidative coupling of amines.

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TL;DR: In this article, the performance of three pyrido[1,2-a]benzimidazoles for steel corrosion in hydrochloric acid solution were investigated through a weight loss test, electrochemical techniques, surface morphology (SEM, XPS), and theoretical methods.
Abstract: The inhibition performance of three pyrido[1,2-a]benzimidazoles, namely, benzo[4,5]imidazo[1,2-a]pyridine (BIP), 2-methylbenzo[4,5]imidazo[1,2-a]pyridine (MBIP), and 2-(trifluoromethyl)benzo[4,5]imidazo[1,2-a]pyridine (TBIP), for steel corrosion in hydrochloric acid solution were researched through a weight loss test, electrochemical techniques, surface morphology (SEM, XPS) studies, and theoretical methods. The experimental results revealed that TBIP, BIP, and MBIP had excellent inhibition performance, and their maximum inhibition efficiencies at 0.25 mmol L−1 were 95.48%, 97.65%, and 98.96%, respectively. The properties of these inhibitors are considered to be mixed-type, and their adsorption mode belongs to the Langmuir isothermal type. The formation and properties of an adsorbed film on a steel surface were investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Quantum chemical calculations provided insightful quantitative information to conclude the correlation between the molecular structures and inhibition performance. Molecular dynamics (MD) simulations were carried out to explore the configurationally adsorption behavior of these pyrido[1,2-a]benzimidazoles on Fe(110) surface, and the binding energy of these three inhibitors followed the order MBIP > BIP > TBIP, which is consistent with the experimental evaluation results.

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TL;DR: In this paper, the authors provide an in-depth overview of some of the recent advances in the development of functional nanomaterials used for the environmental remediation of a variety of pollutants.
Abstract: Accessibility to sufficient clean and fresh water for human consumption is one of the most important issues worldwide, and thus extensive research has been conducted to address this issue. Nowadays, nanotechnology has become a fast-growing technology due to the features of engineered nanomaterials (NMs). Recent advances in nanotechnology provide leapfrogging approaches for contaminant removal by overcoming the shortcomings of existing treatment technologies and offering cost-effective treatment methods with high capacity. The goal of this review is to provide an in-depth overview of some of the recent advances in the development of functional NMs used for the environmental remediation of a variety of pollutants. In this critical review, a new and different categorization of NMs including carbonaceous nanostructures, nanoparticles and nanocomposites is provided. The properties, removal mechanism of pollutants by different NMs, advantages and disadvantages of each group of NMs and their recent development in water, wastewater and groundwater treatment are reviewed and scrutinized. Results revealed that among the different NMs, graphene and its derivatives (e.g. graphene oxide, reduced graphene oxide, graphene-based metals and metal oxide) with excellent environmental compatibility and selectivity, large surface area and high purity, exhibit great absorption capacity because they trap electrons, preventing their recombination. Due to the abundance, unique electronic structure, high porosity, stability, efficient light absorption and suitable charge transfer properties of metal oxides, they are mainly used as catalysts in photocatalytic reactions. The discovery of oxy-acids is another important finding in recent years. In some cases, oxy-acids exhibit higher photoactivity and surface areas and cost less than metal oxides. Thus, to benefit from the advantages of different NMs, binary or ternary composites of metal, metal oxides, oxy-acids and others have been developed. This strategy has led to an increase in surface area and a decrease in band gap, which can enhance environmental contaminant cleanup. Moreover, numerous recent studies have extensively highlighted their results and key findings. Finally, this review will present new horizons for the purposeful application of NMs in remediation by considering the associated challenges, including risk, toxicity and their fate in the environment.

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TL;DR: In this paper, a batch of experiments were conducted to investigate the adsorption isotherm, kinetics and mechanism of Cr(VI) onto MCB20, and the results indicated that the maximum adorption capacity achieved was 25.94 mg g−1.
Abstract: Magnetic modified-corncob biochar with an impregnation ratio of iron at 20% (w/w) was used for removal of Cr(VI) from aqueous solution. Batch adsorption experiments were conducted to investigate the adsorption isotherm, kinetics and mechanism of Cr(VI) onto MCB20. The results indicated that the maximum adsorption capacity achieved was 25.94 mg g−1. The adsorption kinetic data were found to fit best to the pseudo-second order model with a high correlation coefficient (R2 = 0.992). The adsorption mechanisms of Cr(VI) onto MCB20 were electrostatic attraction, anion exchange and adsorption coupled-reduction. The adsorption mechanisms occurring between Cr(VI) anions and MCB20 were due to mainly the contribution of Fe3O4 present in the corncob biochar structure after magnetization by FeCl3. Among the aforementioned mechanisms, adsorption coupled-reduction plays a vital role in removal of Cr(VI) by enhancement of the reduction of Cr(VI) to Cr(III) through generation of electron-donor groups (hydroxyl groups) on the MCB20 surface. Then, Cr(VI) interacted with the electron-donor groups and Cr(VI) is reduced to Cr(III). Besides, Fe2+ ions in the MCB20 structure were simultaneously oxidized to Fe3+ ions and enhanced the transformation of Cr(VI) into Cr(III). The reduced Cr(III) cations, finally, were adsorbed by MCB20 through substitution of Fe3+ with Cr3+ under acidic conditions, complexation with surface functional groups of MCB20 and formation of Cr(OH)3. This study both developed a new way to produce a low cost adsorbent for removal of Cr(VI) from aqueous solution and solved waste by waste.

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TL;DR: In this paper, the authors focus on the recent progress in photoacoustic imaging and photothermal therapy in the NIR-II window and summarize the prospects and challenges of both photothermal and imaging-guided photothermal imaging.
Abstract: The second near-infrared (NIR-II) window, with a broadband absorption ranging from 1000 nm to 1350 nm, has received increasing attention for photoacoustic imaging and imaging-guided NIR-II photothermal therapy. Compared to conventional nanoagents in the first near-infrared (NIR-I) window, with an optical absorption of 700–1000 nm, NIR-II nanoagents offer various merits such as high-performance photothermal treatment outcomes and photoacoustic imaging with both deeper tissue penetration and higher SNR. Thus, this review focuses on the recent progress in photoacoustic imaging and photothermal therapy in the NIR-II window. The merits of the NIR-II window relative to the NIR-I window are systematically compared. This is followed by a summary of nanoagents in the NIR-II window and their biomedical application, including photoacoustic imaging in the NIR-II window and imaging-guided NIR-II photothermal therapy. Finally, the prospects and challenges of both photoacoustic imaging and photothermal therapy in the NIR-II window are summarized.

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TL;DR: Binding study of triamcinolone with BSA through in vitro and in silico approaches, helping in the development of drugs with better therapeutic efficacy.
Abstract: The biomolecular interaction of triamcinolone with bovine serum albumin (BSA) was studied using various multi-spectroscopic techniques in combination with in silico studies. UV-visible absorption, fluorescence spectroscopy and resonance Rayleigh scattering studies confirmed the formation of a BSA–triamcinolone complex. The binding constant was found to be in the order of 103 M−1. Conformational and microenvironmental changes in BSA after addition of triamcinolone were confirmed by circular dichroism and 3D fluorescence spectroscopy, respectively. The negative values of ΔG and ΔH confirmed spontaneous and exothermic binding. The average binding distance between BSA and triamcinolone was also calculated through FRET. Additionally, the effect of metal ions and β-cyclodextrin on the binding of triamcinolone with BSA was also investigated. Molecular docking and site marker displacement experiments unveiled the binding of triamcinolone to BSA at site III located in subdomain IB of BSA. Molecular dynamics simulation showed lower RMSD values and negative total energy, suggesting favourable binding between BSA and triamcinolone.

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TL;DR: In this paper, the NiCo2S4@MoS2 materials have been successfully prepared using zeolitic imidazolate frameworks as templates, including transformation to bimetallic layered double hydroxide, and sequential sulfuration.
Abstract: The development of bifunctional electrochemically-active micro-/nanomaterials with heterostructures for both supercapacitors and hydrogen evolution reaction (HER) enables the possibility to integrate energy storage and conversion into one single system. Herein, heterostructural NiCo2S4@MoS2 materials have been successfully prepared using zeolitic imidazolate frameworks as templates, including transformation to bimetallic layered double hydroxide, and sequential sulfuration. The smart process entails an assembly of MoS2 nanosheets on NiCo2S4 nanobuilding blocks with hollow core–shell nanoarchitectures. Specifically, when tested as an electrode in a supercapacitor, it can deliver an increased specific capacitance of 860 F g−1 at a current density of 1 A g−1, superior rate capability and cyclic stability. Furthermore, the NiCo2S4@MoS2 heterostructure also efficiently electrocatalyzes the HER in an alkaline electrolyte with a low overpotential of 194 mV, a favorable HER kinetics and better long-term stability. Results of both scenarios attest to the enhanced electrochemical performance of the NiCo2S4@MoS2 heterostructure compared to its NiCo2S4 counterpart, which is attributed to the hollow porous core–shell structures, nanointerface engineering and the synergistic effect between NiCo2S4 and MoS2. This work will broaden our horizons in designing and fabricating multifunctional active materials for next generation energy storage and conversion applications.

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TL;DR: In this paper, a novel copper-II phthalocyanine (CuPc)-modified multiwalled carbon nanotube-based electrode was prepared for sensitive electrochemical detection of bisphenol A, by the modification of a pencil graphite electrode via the adsorption method.
Abstract: A novel copper(II) phthalocyanine (CuPc)-modified multiwalled carbon nanotube-based electrode was prepared for the sensitive electrochemical detection of bisphenol A, by the modification of a pencil graphite electrode via the adsorption method. The synthesized novel CuPc was characterized by spectroscopic methods and the electrodes were characterized by electrochemical, spectroscopic and microscopic methods. The limit of detection (LOD, S/N = 3) was calculated as 0.0189 μM for bisphenol A. The experimental parameters such as pH and adsorption time were optimized for the electrochemical detection of bisphenol A. The detection was done in real samples, with a high recovery value (>98%), indicating the useful application of modified electrodes as electrochemical sensors for bisphenol A. The electrodes showed excellent repeatability and stability in the differential pulse voltammetric detection of bisphenol A. The prepared novel sensor can be used for the detection of bisphenol A in many environmental analyses due to its simplicity, low cost, environmental friendliness and high sensitivity.