Search

Graphitic carbon nitride (g-C3N4) has been demonstrated to be a rising star among semiconductor materials for photocatalytic hydrogen (H2) production. However, pristine g-C3N4 usually suffers from inferior activity due to the inadequate visible light harvesting capacity and quick charge recombination. Herein, porous P doped g-C3N4 nanosheets (PCNNSs) were fabricated via a simple thermal condensation of adenosine phosphate and urea followed by thermal exfoliation method. The synergetic effect of the porous structure and P dopant can provide abundant active sites for the photocatalytic reaction, which can enhance light absorption range extending from 450 nm to 700 nm attributed to the n→π* electronic transition, and improve hydrophilicity for easier water molecules adsorption via introducing hydroxyl groups. Furthermore, impurity level caused by the P dopant would change the excitation process and accelerate the charge separation efficiency. Therefore, the PCNNSs exhibited significantly elevated photocatalytic H2 generation performance (9523.7 μmolg-1h-1) under visible-light (λ > 420 nm) irradiation, which was about 20 times that of unmodified g-C3N4 (458 μmol-1h-1).

Non-thermal plasma has increasingly been used for surface modification of various materials as a novel green technology. In this study, we prepared potato starch nanocrystals (SNCs) assisted by dielectric barrier discharge plasma technology and investigated its multiscale structure, physicochemical properties and rheology. Plasma treatment did not change the morphology and crystalline pattern of SNCs but reduced the crystallinity. The amylose content, swelling power, gelatinization temperature, and apparent viscosity of SNCs decreased after the plasma process by depolymerizing the amylopectin branch chains and degrading SNCs molecules. Besides, plasma increased the rapidly digestible starch and resistant starch content. Changes in rheological properties of plasma treated SNCs suggested that the plasma process increased the flowing capacity. The effective structural and functional changes of plasma treated SNCs confirm that plasma technology has great potential for modification of SNCs.

Effects of repeated annealing treatments (8 cycles, 12 h each) or continuous annealing treatments (12–96 h) at 50 °C on structural, physicochemical, and digestive properties of normal and waxy wheat starches were investigated. Wheat starches retained the original crystalline structure of A-type after annealing. Annealing treatments increased crystallinity, short chain of amylopectin, viscosity, and gelatinization temperatures of starch. However, molecular weight, long chain of amylopectin, solubility, and swelling power of starch decreased after annealing. Additionally, annealing reduced the in vitro digestibility of wheat starches. The changes in properties of starch varied depending on starch type, normal or waxy, and annealing methods, repeated or continuous. The repeated annealing was found to be more effective in modification of normal wheat starch properties. However, continuous annealing efficiently modified properties of the waxy wheat starch. The obtained results may help in choosing appropriate applications of annealed wheat starches in the food industry.

In this work, a new class of heterostructure photocatalyst has been fabricated, which silver/silver chloride nanocubes are well-dispersed on titanium dioxide nanofibers by means of a facile precipitation process combined with photoreduction method. This sort of heterostructure shows an excellent photocatalytic activity superior to the pure TO 2 nanofibers, Ag/AgCl powder and Ag/TiO 2 nanofibers for decomposing organic contaminants driven by visible light. The improved photocatalytic activity might be due to the surface plasmon resonance effect of Ag and the formation of heterojunction between Ag, AgCl and TiO 2 , which can effectively enhance visible light absorption and accelerate the charge separation and transfer. Significantly, the multiple cycle experiments for repeated use have proved that the catalyst is stable, segregative and recyclable. Finally, a possible mechanism related to the charge separation and the photocatalytic degradation of organics is also provided.

Stimuli-sensitive nanocomposites have received special attention because of their potential applications in various fields. In this work, we report a novel thermo-responsive photoluminescent silver clusters/hydrogel nanocomposite with red emission, as a probe for highly sensitive and selective detection of Cr(VI) in aqueous solutions. The hydrogel nanocomposites integrate the advantages of p(NIPAM-co-AAc) hydrogel submicron particles and Ag clusters: the p(NIPAM-co-AAc) hydrogel submicron particles can act as templates for Ag nanoclusters and exhibit thermo-responsive properties. In addition, Ag nanoclusters endow excellent photoluminescent properties to our nanocomposites, resulting in photoluminescent sensors. As a result, we obtained novel thermo-responsive Ag clusters/p(NIPAM-co-AAc) hydrogel nanocomposites through photoreduction process. The photoluminescence (PL) intensity of as-prepared nanocomposites exhibited a linear and reversible response from 2 to 85 °C and displayed a high PL quenching for the sensitive and selective detection of Cr(VI), rather than Cr(III). The limit of detection could reach as low as 1 ppb, which indicates that it is an ideal sensor tool for environmental monitoring, laboratory detections and various other applications.

This study explored the potential application of physical combined enzyme treatment to modify starch granules. Starch was modified by exposure to cold plasma (CP) for 1, 3, and 9 min and to pullulanase (PUL) for 12, 24, and 36 h. Individual treatments with CP and PUL somewhat modified starch structure and physicochemical properties. Nevertheless, compared with native starch and individual treatments, CP-PUL combined treatment significantly (p 0.05) promoted the subsequent structural modification, increased the short-chain ratio and the amylose content, reduce the molecular weight and the relative crystallinity, and disturb the short-range order. CP also improved the properties of PUL-modified starch, including enhanced solubility, thermal properties and resistance to enzymatic hydrolysis but worsened swelling power and peak viscosity properties. This research provides a new perspective for the rational application of CP-PUL co-treated starch in the food industry.

A novel photocatalyst Ag-AgBr/TiO2 heterostructured nanofibers was fabricated by means of combining solvothermal technique with photoreduction method based on the electrospun TO2 nanofibers support. And, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis spectrophotometer (UV–vis), and photoluminescence (PL) measurements were used to characterize the structure, morphology, and properties of the as-prepared photocatalysts. Further, the photocatalytic activity of photocatalysts was tested by degrading methylene blue dye under visible light. As a result, the photocatalytic activity of the Ag-AgBr/TiO2 heterostructured nanofibers is far superior to that of TiO2 nanofibers and Ag-AgBr power, which could be attributed to the surface plasmon resonance effect of Ag nanoparticles and the synergetic effect between the three components of Ag, AgBr and TiO2. Significantly, the stability and recycling of the photocatalyst was also investigated. The possible mechanism related to the photocatalytic performance of the Ag-AgBr/TiO2 heterostructured nanofibers was also gone deep into discuss.

One-dimensional BiOCl/PAN composite nanofibers which are composed of bismuth oxychloride (BiOCl) nanosheets on electrospun polyacrylonitrile (PAN) nanofibers were fabricated by combining electrospinning technique and solvothermal method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis diffuse reflectance, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, thermal gravimetric and differential thermal analysis, were used to characterize the as-fabricated BiOCl/PAN composite nanofibers. The results revealed that BiOCl nanosheets were successfully immobilized on electrospun PAN nanofibers. The contents of the BiOCl nanosheets were controlled by adjusting the precursor concentrations for the fabrication of BiOCl/PAN composite nanofibers during the solvothermal synthesis processes. It was found that some interactions might exist between BiOCl and PAN molecules of BiOCl/PAN composite nanofibers. The obtained BiOCl/PAN composite nanofibers exhibited high photocatalytic activity for degradation of rhodamine B under ultraviolet light irradiation. The trapping experiments confirmed that the main active species for photocatalysis was hydroxyl radicals, which was produced by both the oxidative pathway and reductive pathway. Notably, the BiOCl/PAN composite nanofibers photocatalysts not only had good reusable property because of their one-dimensional structure and flexibility but also retained high photocatalytic stabilities after several cycles due to the interaction between BiOCl and PAN molecules.

In this paper, Bi(2)MoO(6) microtubes (BMO-MTs) were obtained by a two-step fabrication route. By using the electrospun polyacrylonitrile (PAN) microfibers as structure-directing hard template and through ethylene glycol solvothermal method, polyacrylonitrile/Bi(2)MoO(6) (PAN/BMO) hybrid microfibers with core-shell structures were prepared. Through heat treatment of the as-prepared PAN/BMO to remove the PAN core, Bi(2)MoO(6) with tubes-structured were obtained. The thickness of BMO-MTs was controlled by changing the Bi(2)MoO(6) loading percentage of PAN/BMO which could be obtained through ethylene glycol solvothermal process with precursor different concentration for the preparation of Bi(2)MoO(6). And, the crystal structure and morphology of BMO-MTs strongly depended on the calcination temperature when heat-treating the as-prepared PAN/BMO. Photocatalytic tests show that the BMO-MTs possess a much higher degradation rate of Rhodamine B (RB) than that of Bi(2)MoO(6) prepared by solid-state reaction and conventional P25. The improved photocatalytic performance could be ascribed to the hollow multi channelled structure and large surface area. The BMO-MTs could be reclaimed easily by sedimentation from the photocatalytic reaction solution due to the large length to diameter ratio of one-dimensional tubes structures. Moreover, such simple and versatile strategy can provide a general way to fabricate other tubes structures of Bi(III)-containing oxides, such as Bi(2)WO(6) and BiVO(4) microtubes.

In this paper, we have successfully fabricated TiO2/PbS heteroarchitectures with high-quality single-crystalline PbS nanostructures well-erected on electrospun TiO2 nanofibers matrices via hydro(solvo)thermal method using l -cysteine as the sulfur donor and chelating reagent. The experiment results showed that the morphology and size of secondary PbS nanostructures grown on TiO2 nanofibers can be changed significantly by utilizing two kinds of different reaction solvents (water and acetylacetone, respectively). In case of water serving as solvent, the superb cube-shaped PbS nanocrystals with the edge length ranging from 150 to 300 nm were prepared. While acetylacetone acting as solvent, the high-density PbS nanoparticles with 10–30 nm in length were obtained. And, it is interesting that PbS nanostructures were not only uniformly monodispersed but also closely attached to TiO2 nanofibers surface. What is more, the further studies suggested that the formation of TiO2/PbS heteroarchitectures might take on chelation-anchoring-nucleation-directional growth strategy.

ZnO/Bi2O3nanofibers were synthesized by a simple electrospinning method and both the UV and visible light responsive photocatalytic properties were studied by the decolorization of RhB dye. Thermogravimetric analysis/differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), and UV-vis diffuse reflectance spectra (DRS) were employed to study the structure, morphology, and optical properties of the ZnO/Bi2O3nanofibers, respectively. The relationship between the ZnO/Bi2O3ratio and photocatalytic activity was also studied, and the composite with a molar ratio of 23 : 1 demonstrated the best activity under both excitations. The photocatalytic mechanisms for the composite fibers can be described as the direct photocatalysis under UV excitation and photosensitation for visible light irradiation. The enhanced photocatalytic activities can be ascribed to the effective electron-hole pairs separation that leads to the promoted photocatalytic efficiency.

TiO2 nanoparticles were successfully fabricated on electrospun polyacrylonitrile (PAN) nanofibers via the coupling of electrospinning and hydrothermal pathway. A straightforward photocatalysis oxidation process has been developed for simultaneous desulfurization and denitrification of flue gas using the TiO2–PAN photocatalyst. Also, the influences of some important operating parameters, such as titanium loading content of catalyst, flue gas humidity, flue gas flow, and inlet flue gas temperature on removal efficiencies of SO2 and NO were investigated. The results demonstrated that removal efficiencies of 99.3% for SO2 and 71.2% for NO were attained under the following optimal experiment conditions: titanium loading content, 6.78 At %; gas flow rate, 200 mL/min; flue gas humidity, 5%; inlet flue gas temperature, 40 °C. Furthermore, the presumed reaction mechanism of SO2 and NO removal using TiO2–PAN photocatalyst under UV light was proposed.

A three-dimensional (3D) free-standing network composed of cross-linked carbon@Au core–shell nanofibers was fabricated by combining the electrospinning technique and an in situ reduction approach. The results showed that a uniform Au layer of approximately 5 nm thickness was formed around the electrospun carbon nanofiber. What's more, it's interesting to note that the Au layer was composed of small Au nanoparticles. And, the as-prepared CNFs@Au network exhibited excellent catalytic activity for the reduction of 4-nitrophenol (4-NP) based on the electron-rich catalytic platform arising from the synergistic effect between carbon and Au. Notably, the free-standing 3D nanofibrous cross-linked network structure could improve the catalyst's performance in separation and reuse.

Carbon-modified BiVO(4) microtubes embedded with Ag nanoparticles (BVO@C/Ag MTs) were obtained by a two-step fabrication route. First, the BiVO(4)@carbon core-shell microtubes (BVO@C MTs) were fabricated by using BiVO(4) microtubes (BiVO(4) MTs) as a hard-template through a hydrothermal approach. Next, small Ag nanoparticles (Ag NPs) with well-dispersed distribution were assembled inside the carbon layer of the BVO@C MTs via an in situ reduction method. The results showed that small Ag NPs were well dispersed inside the carbon layer of approximately 8 nm in thickness around the BiVO(4) microtubes. The photocatalytic studies revealed that the BVO@C/Ag MTs exhibited the highest photocatalytic activity for photodegradation of rhodamine B (RB) compared to the pure BVO-MTs, BVO@C MTs under visible light irradiation. The high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of BiVO(4), carbon, and Ag and the improved visible light utilization from the sensitizing effects of carbon layers both contribute to the enhanced photocatalytic activity. The BVO@C/Ag MTs did not exhibit any significant loss of activity after three cycles of RB photodegradation, which results from the fact that the presence of the carbon layer could inhibit loss and oxidation of Ag NPs during repeated applications. The BVO@C/Ag MTs could be easily recovered by sedimentation due to their one-dimensional nanostructural property.

Herein, we have demonstrated that the electrospun nanofibers of TiO(2)/CdS heteroarchitectures could be fabricated through combining electrospinning technique with hydrothermal process. The configuration, crystal structure, and element composition of the as-prepared TiO(2)/CdS heteroarchitectures were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), resonant Raman spectrometer, X-ray photoelectron spectroscopy (XPS). The results indicated that the high-density hexagonal wurtzite CdS crystalline particles of ca. 6-40 nm in diameter were uniformly and closely grown on anatase TiO(2) nanofibers. Especially, the light-absorption properties as well as photocatalytic characteristics of pure TiO(2) nanofibers and TiO(2)/CdS heteroarchitectures with different amount loading of CdS were also investigated. The absorption of TiO(2)/CdS heteroarchitectures was extended to the visible due to effective immobilization of sensitizing agent CdS on TiO(2). In contrast with the pure TiO(2) nanofibers, the TiO(2)/CdS heteroarchitectures showed excellent photocatalytic activity by using rhodamine B dye as a model organic substrate under visible-light irradiation. It was worth noting that the cooperative photocatalytic mechanism of the TiO(2)/CdS heteroarchitectures was also discussed.

TiO2/polyacrylonitrile (TiO2/PAN) hybrid nanofibers with small TiO2 nanoparticles well-immobilized on the electrospun PAN nanofibers have been successfully fabricated by means of a combination of an electrospinning technique and a hydrothermal process. The as-fabricated hybrid nanofibers were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. The results revealed that the TiO2/PAN hybrid nanofibers possessed a large surface area as well as being flexible in nature. Such hybrid nanofibers materials have exhibited outstanding performance for the photocatalytic degradation of phenol under UV light irradation. And, by adjusting the operating parameters during the photocatalytic process, the results further showed that the photoreactor pattern, initial pH value and concentration of phenol solution had important influence on phenol degradation. What's more, repeating the experiments five times indicated that the catalyst is stable and recyclable.

In this work, Ag/TiO2 nanoheterostructures with Ag nanocrystals well-grown on TiO2-based nanofiber mats have been achieved by means of a novel and straighforward protocol combining an electrospinning technique and a solvothermal process. The experimental results indicated that the morphology and size of the secondary Ag nanostructures could be tailored by altering the experimental parameters, such as the reaction time and solvent as well as the reducing agent in the solvothermal treatment. The investigation of photocatalytic ability showed that the Ag/TiO2 nanoheterostructures possess an excellent photocatalytic activity superior to the pure TiO2 nanofiber for the degradation of Rhodamine B (RB) dye driven by visible light. The results indicated that Ag might be responsible for the visible light induced photocatalytic degradation by improving the photogenerated electrons and holes separation as well as charge migration, allowing both the electrons and holes to partake in the overall photocatalytic reaction. In addition, Ag has a good light absorption capability, extending the response of TiO2 to visible light. Finally, the corresponding possible mechanism related to the photocatalytic performance of the Ag/TiO2 nanoheterostructures was discussed in detail. Additionally, the separation and recovery process of the Ag/TiO2 nanoheterostructures might be easily acheived by sedimentation without a decrease in the photocatalytic ability because of their particular one-dimensional nanostructured nature.