Ternary heterostructured nanofibers (NFs) consisting of plasmonic noble metal nanoparticles (Au, Ag, or Pt NPs), graphitic carbon nitride nanosheets (g-C3N4 NSs), and TiO2 NPs were synthesized in situ via a facile electrospinning technique combined with a subsequent thermal oxidation/reduction process. The thermal-reduced plasmonic NPs with sizes from 5 to 10 nm are dispersed uniformly into the heterojunctions of the NFs that are formed by thermal oxidation etching of exfoliated g-C3N4 NSs in the electrospun TiO2 nanofibrous matrix, as evidenced by microscopic and electronic structure analyses. In comparison to single-component photocatalysts, such as g-C3N4 NSs or TiO2 NFs, these ternary heterostructures exhibit significantly high photocatalytic activity for H2 evolution under simulated sunlight irradiation. The enhanced photoactivities are attributed to the strong photosynergistic effect between the surface plasmon resonance (SPR) and the heterojunction interface sensitization, which results in the improvement of charge-carrier generation and separation in the ternary heterostructured NFs. Further investigations indicate that coupling heterojunction sensitization on the g-C3N4/TiO2 interface with Ag SPR effects by plasmonic resonant energy transfer is the optimal strategy for synergistically improving the charge-carrier kinetics to achieve highly efficient photocatalytic H2 evolution. It is believed that our present study offers a promising method for the rational integration of multi-component photocatalytic systems that can realize high photocatalytic performances for use in solar-to-fuel conversion.

Recently, hierarchically porous carbon materials with advantages of hierarchical porosity and large specific surface areas exhibiting desirable capacitive performance have been widely investigated. Herein, a facile and template-free phase separation methodology has been presented to prepare three-dimensional freestanding hierarchically porous carbon (HPC) materials. Importantly, the as-fabricated HPC with highly uniform and well-interconnected pores can afford plentiful transport channels for rapid diffusion of more ions, and the highly conductive cross-linked backbones ensure fast electron transfer, both of which can greatly reduce the internal resistance and improve the electrochemical properties. As expected, the as-fabricated HPC-based supercapacitor has achieved outstanding electrochemical performance with a high cell capacitance of 51 F g−1 at a current density of 0.5 A g−1, good rate capability with 75% capacitance retention of initial capacitance at 32 A g−1 as well as a maximum energy density of 4.5 W h kg−1 at 200 W kg−1 and a maximum power density of 15100 W kg−1 at 3.4 W h kg−1. More significantly, a remarkable cycling stability almost without capacitance loss after the 50000 charge/discharge test at 5 A g−1 has been achieved for the HPC-based supercapacitors. All these results suggest that the as-synthesized HPC has great potential for application not only as a supercapacitor electrode but also as a substrate for supporting capacitive materials.

Freestanding nitrogen-doped porous carbon nanofibers (NPCNFs) are prepared by carbonizing the nitrogen-enriched porous binary polymer precursors of electrospun polyacrylonitrile/polyaniline core–shell composite nanofibers at an appropriate temperature. The obtained freestanding NPCNFs with the advantages of a suitable nitrogen content, hierarchical porosity, large specific surface areas, and good conductivity are very promising to achieve desirable electrochemical performance. As expected, the NPCNFs as electrode materials demonstrate a high specific capacitance of 335 F g−1 at a current density of 0.5 A g−1 and high rate capability with a capacitance retention of 175 F g−1 at 32 A g−1 in a three-electrode configuration test. Particularly, the as-fabricated flexible solid-state supercapacitor based on the freestanding NPCNFs delivers a maximum energy density of 9.2 W h kg−1 at 0.25 kW kg−1 and also presents good cycling stability with 86% capacitance retention after 10000 cycles at a current density of 5 A g−1. Therefore, the freestanding NPCNFs as electrode materials for flexible solid-state supercapacitors might have potential applications in portable and flexible electronics.

•Hierarchically porous carbon can be facilely prepared by a template-free method.•The HPC/PANI composites present high capacitance and rate capability.•The as-assembled HPC/PANI-based device also exhibits good capacitive performance.Freestanding hierarchically porous carbon electrode materials with favorable features of large surface areas, hierarchical porosity and continuous conducting pathways are very attractive for practical applications in electrochemical devices. Herein, three-dimensional freestanding hierarchically porous carbon (HPC) materials have been fabricated successfully mainly by the facile phase separation method. In order to further improve the energy storage ability, polyaniline (PANI) with high pseudocapacitance has been decorated on HPC through in situ chemical polymerization of aniline monomers. Benefiting from the synergistic effects between HPC and PANI, the resulting HPC/PANI composites as electrode materials present dramatic electrochemical performance with high specific capacitance up to 290 F g−1 at 0.5 A g−1 and good rate capability with ∼86% (248 F g−1) capacitance retention at 64 A g−1 of initial capacitance in three-electrode configuration. Moreover, the as-assembled symmetric supercapacitor based on HPC/PANI composites also demonstrates good capacitive properties with high energy density of 9.6 Wh kg−1 at 223 W kg−1 and long-term cycling stability with 78% capacitance retention after 10 000 cycles. Therefore, this work provides a new approach for designing high-performance electrodes with exceptional electrochemical performance, which are very promising for practical application in the energy storage field.

Design and synthesis of hierarchical carbon hybrid based pseudocapacitive electrodes is the next step forward for achieving high-performance supercapacitors. Here, the freestanding electrospun carbon nanofibers/carbon nanotubes/polyaniline (CNFs/CNTs/PANI) ternary composites have been fabricated successfully. Importantly, the hierarchical carbon hybrids by dense CNT forests decorated CNFs serving as supports are crucial for the ternary composites to achieve high electrochemical properties. The hierarchical CNFs/CNTs hybrids serving as inner current collectors can afford plentiful transport channels for more rapidly transporting and collecting electrons, greatly reduce the ion diffusion length, and increase the utilization of pseudocapacitive materials. As expected, the ternary composites as electrodes present high specific capacitance (i.e., 315 F/g at 1 A/g) and dramatic rate capability (i.e., 235 F/g at 32 A/g) in three-electrode configuration. Moreover, the as-fabricated flexible solid-state supercapacitor based on the ternary composites also achieves desired electrochemical properties with high capacitance, high-rate capability, high energy/power density (i.e., 5.1 Wh/kg at 10.1 kW/kg), and remarkable cycling stability (i.e., 92% capacitance retention after 10 000 cycles at 2 A/g). These extraordinary electrochemical properties can be attributed to the well-designed structural advantages and synergistic effects.Keywords: Carbon nanofibers; Carbon nanotubes; Flexibility; Polyaniline; Solid-state supercapacitors;

•3D MoS2 nanosheet/TiO2 nanofiber heterostructures were successfully prepared.•The 3D heterostructures show enhanced photocatalytic performance.•A possible photocatalytic mechanism under UV light irradiation was proposed.•The 3D heterostructures could be reclaimed easily.We employed electrospun TiO2 nanofibers (NFs) as a synthetic template to develop three-dimensional (3D) MoS2 nanosheet/TiO2 nanofiber (MoS2/TiO2) heterostructures using a simple hydrothermal method. The prepared 3D MoS2/TiO2 heterostructures exhibited a higher performance in photocatalytic degradation of the dye molecules (rhodamine B and methyl orange) than pure TiO2 NFs under UV light irradiation. The enhanced photocatalytic activity might be attributed to the formation of heterostructures between TiO2 and MoS2, in which MoS2 not only served as electron trapper to improve the separation of photogenerated electron-hole pairs, but also provided a greater number of active adsorption sites for the photodegradation of pollutants. The 3D heterostructure photocatalysts could be easily recycled by sedimentation due to their nanofibrous network structure. The photocatalytic mechanism of 3D MoS2/TiO2 heterostructures was also proposed.

We highlight a hydrothermal synthetic approach at low temperatures to prepare carbon-rich graphitic carbon nitride nanosheets, which show enhanced photocurrent and photocatalytic activity, due to their improved electron transport ability along the in-plane direction and increased lifetime of photoexcited charge carriers.

In this paper, a two-step synthesis route combining an electrospinning technique and a solvothermal method has been accepted as a straightforward protocol for the exploitation of BiOCl–carbon nanofiber (CNF) hierarchical heterostructures. Photocatalytic tests showed that the BiOCl–CNF heterostructures possess a much higher degradation rate for 4-nitrophenol (4-NP) than pure BiOCl. The enhanced photocatalytic activity could be attributed to the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the BiOCl–CNF heterojunction interface. The OH˙ radicals played a critical role in the photocatalytic degradation of 4-NP over the BiOCl–CNF heterostructures. Moreover, the heterostructures could be recovered easily by sedimentation without a decrease in photocatalytic activity.

In this work, p-MoO3 nanostructures/n-TiO2 nanofiber heterojunctions (p-MoO3/n-TiO2–NF-HJs) were obtained by a two-step fabrication route. First, MoO2 nanostructures were hydrothermally grown on electrospun TiO2 nanofibers. Second, by thermal treatment of the obtained MoO2 nanostructures/TiO2 nanofibers, p-MoO3/n-TiO2–NF-HJs were obtained due to the phase transition of MoO2 to MoO3. With increasing the concentration of molybdenum precursor in hydrothermal process, the morphologies of MoO2 changed from nanoparticles to nanosheets, and then fully covered shells with an increased loading on TiO2 nanofibers. After calcination, the obtained p-MoO3/n-TiO2–NF-HJs possessed similar morphology to that without thermal treatment. X-ray photoelectron spectra showed that both Ti 2p and OTi–O 1s peaks of p-MoO3/n-TiO2–NF-HJs shifted to higher binding energies than that of TiO2 nanofibers, suggesting electron transfer from TiO2 to MoO3 in the formation of p–n nanoheterojunctions. The p–n nanoheterojunctions decreased photoluminescence intensity, suppressed photogenerated electrons and holes recombinations, and enhanced charge separation and photocatalytic efficiencies. The apparent first-order rate constant for the degradation of RB by p-MoO3/n-TiO2–NF-HJs with nanosheets surface morphology was two times that of TiO2 nanofibers. For the core/shell structure of p-MoO3/n-TiO2–NF-HJs, the internal electric field of p–n junction forced the photogenerated electrons transferring to TiO2 cores, then decreased the surface photocatalytic reactions and led to the lowest photocatalytic activity among the p-MoO3/n-TiO2–NF-HJs.Keywords: electrospinning; heterojunction; MoO3; nanofibers; photocatalysis; TiO2;

CuO nanofibers (NFs) were fabricated via the traditional electrospinning technique and subsequent thermal treatment processes. Using CuO NFs as precursors and glucose as a reducing agent, CuO/Cu2O NFs, with high surface areas and ultralong one dimensional (1D) nanostructures, were obtained by a partial reduction of CuO NFs. Comparing with pure CuO NFs, CuO/Cu2O NFs, as non-enzymatic electrode materials, showed a much higher sensitivity of 830 μA mM−1 cm−2 and a much wider detection range from 0.5 mM to 10 mM for the amperometric detection of glucose. The excellent electrocatalytic performances could be ascribed to the following advantages: (1) the CuO/Cu2O NFs with Cu(II)/Cu(I) multiple oxidation states system could promote the redox reactions between electrode materials and glucose, and the reactive sites became more active due to the synergic effect; (2) the surface of CuO/Cu2O NFs became smoother after partial reduction, resulting in less adsorption of the intermediates during the oxidation of glucose, generating the enlarged detection range. Therefore, the CuO/Cu2O composite NFs electrode materials, with a multiple oxidation states system, would be promising candidates for the development of non-enzymatic glucose sensors.

Bi2WO6–carbon nanofibers (Bi2WO6–CNFs) heteroarchitectures were fabricated by two steps consisting of the preparation of CNFs by electrospinning and growth of Bi2WO6 on the CNFs through ethylene glycol solvothermal processing. The results showed that the loading amounts of Bi2WO6 on the surface of CNFs could be controlled by adjusting the precursor concentration for the fabrication of Bi2WO6–CNFs heteroarchitectures during the solvothermal process. The photocatalytic tests revealed that the obtained Bi2WO6–CNFs heteroarchitectures showed higher photocatalytic property under visible light to degrade Rhodamine B than pure Bi2WO6 synthesized by solvothermal process in the absence of CNFs owing to improved separation efficiency of photogenerated electrons and holes. Moreover, the Bi2WO6–CNFs heteroarchitectures could be separated easily by sedimentation due to their one-dimensional nanostructural property. Meanwhile, the photocatalytic activity of Bi2WO6–CNFs heteroarchitectures was stable during the recycling due to the strong interactions between Bi2WO6 nanosheets and CNFs. Trapping experiment suggested that \({\text{O}}_{ 2}^{ \cdot - }\), instead of OH·, was the main active species during the photocatalytic process of the Bi2WO–CNFs heteroarchitectures.

Well-designed hierarchical nanostructures with one dimensional (1D) TiO2 nanofibers (120–350 nm in diameter and several micrometers in length) and ultrathin hexagonal SnS2 nanosheets (40–70 nm in lateral size and 4–8 nm in thickness) were successfully synthesized by combining the electrospinning technique (for TiO2 nanofibers) and a hydrothermal growth method (for SnS2 nanosheets). The single-crystalline SnS2 nanosheets with a 2D layered structure were uniformly grown onto the electrospun TiO2 nanofibers consisted of either anatase (A) phase or anatase–rutile (AR) mixed phase TiO2 nanoparticles. The definite heterojunction interface between SnS2 nanosheets and TiO2 (A or R) nanoparticles were investigated by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). Moreover, the as-prepared SnS2/TiO2 hierarchical nanostructures as nanoheterojunction photocatalysts exhibited excellent UV and visible light photocatalytic activities for the degradation of organic dyes (rhodamine B and methyl orange) and phenols (4-nitrophenol), remarkably superior to the TiO2 nanofibers and the SnS2 nanosheets, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the SnS2/TiO2 heterojunction. Significantly, the SnS2/TiO2 (AR) hierarchical nanostructures as the tricomponent heterojunction system possessed stronger photocatalytic activity than the bicomponent heterojunction system of SnS2/TiO2 (A) hierarchical nanostructures or TiO2 (AR) nanofibers, which was discussed in terms of the three-way photosynergistic effect between SnS2, TiO2 (A) and TiO2 (R) component in the SnS2/TiO2 (AR) heterojunction resulting in the high separation efficiency of photoinduced electron–hole pairs, as evidenced by photoluminescence (PL) and surface photovoltage spectra (SPS).

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.

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.

One-dimensional In2O3 nanocubes/carbon nanofibers (CNFs) heterostructures have been successfully obtained by a simple combination of electrospinning technique and solvothermal process for the first time. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and IR spectra. The results revealed that the secondary In2O3 nanocubes were successfully grown on the primary CNF substrates. Photocatalytic tests displayed that the In2O3/CNFs heterostructures possessed a much higher degradation rate of rhodamine B (RB) than the pure In2O3 under visible light. The enhanced photocatalytic activity could be attributed to the formation of heterostructures, which might improve the separation of photogenerated electrons and holes. Moreover, the In2O3/CNF heterostructures could be easily recycled without the decrease of the photocatalytic activity due to their one-dimensional nanostructural property. The morphology of the secondary In2O3 nanostructures (nanocubes, nanoagglomerates or nanoparticles) could be controlled by adjusting the additives including CO(NH2)2 and a defined amount of water. The general growth mechanisms for the In2O3 nanostructures have also been discussed.

Tubular nanocomposites of silver nanoparticles (AgNPs)/silica nanotubes (SNTs) with the nearly uniform diameters of 250–350 nm were successfully fabricated by combining the single capillary electrospinning technique (for SNTs as the supports) and an in situreduction approach (for AgNPs). The highly dispersed AgNPs assembled on the inner and outer surface of SNTs through the in situreduction of Ag+ by Sn2+ ions were confirmed by transmission electron microscopy (TEM), UV-Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). It was interesting to note that the size of AgNPs on the surface of SNTs could be controlled by appropriately adjusting the amount of ammonia solution during the above in situreduction reaction. The catalytic activities of the as-prepared tubular nanocomposites were evaluated by using a model reaction based on the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH4 as the reductant. The results indicated that all the tubular nanocomposites catalysts with high specific surface area (185–250 m2 g−1) exhibited excellent catalytic activities because the highly dispersed AgNPs were exposed on the inner and outer surface of electrospun SNTs, allowing effective contact with the reactants and catalysis of the reaction. In particular, the tubular nanocomposite catalysts containing small size AgNPs had higher catalytic activities than those containing the large size ones, which was attributed to the size-dependent Ag redox potential and surface-to-volume ratio influencing interfacial electron transfer from AgNPs surface to 4-NP in the presence of highly electron injecting BH4− ions. Those tubular catalysts based on AgNPs/SNTs nanocomposites could be easily recycled without a decrease of the catalytic activities due to their one-dimensional nanostructural property.

In this paper, a facile two-step synthesis route combining an electrospinning technique and solvothermal method has been presented as a straightforward protocol for the exploitation of Bi2MoO6–carbon nanofiber (CNF) hierarchical heterostructures, which are composed of Bi2MoO6 nanosheets on the surface of CNFs. Photocatalytic tests show that the Bi2MoO6–CNF heterostructures possess a much higher degradation rate of Rhodamine B (RB) than pure Bi2MoO6 under visible light. The enhanced photocatalytic activity may be attributed to the extended absorption in the visible light region due to the Bi2MoO6 nanosheets, and the effective separation of the photogenerated carriers driven by the photoinduced potential difference produced at the Bi2MoO6–CNF heterojunction interface. Moreover, the heterostructures could be recovered easily by sedimentation without a decrease in their photocatalytic activity. The morphology of the secondary Bi2MoO6 nanostructures could be controlled by adjusting the experimental parameters, including the precursor concentration, temperature and solvent during the solvothermal process. As a result, different morphologies of Bi2MoO6–CNF heterostructures, with Bi2MoO6 nanosheets, nanoparticles, nanoflowers and nanorods, were successfully achieved.

Carbon-modified BiVO4 microtubes embedded with Ag nanoparticles (BVO@C/Ag MTs) were obtained by a two-step fabrication route. First, the BiVO4@carbon core–shell microtubes (BVO@C MTs) were fabricated by using BiVO4 microtubes (BiVO4 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 BiVO4 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 BiVO4, 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.

The ZnO quantum dots-SiO2 nanotubes (ZQDs-SNTs) nanocomposite was successfully fabricated by direct heat treatment of the electrospun zinc acetate/tetraethyl orthosilicate (TEOS)/polymer nanotubes (NTs). The results indicated that the ZnO quantum dots (ZQDs) with diameter about 3–5 nm were highly dispersed on the SiO2 nanotubes (SNTs). And, there might be Zn–O–Si bonds between ZQDs and SiO2 matrix, which formed interface states in the ZQDs-SNTs nanocomposite. The photocatalytic studies revealed that the ZQDs-SNTs nanocomposite exhibited high photocatalytic activity to degrade Rhodamine B (RB) under ultraviolet (UV) light irradiation, which might be ascribed to two reasons. The first one was the high dispersity of ZQDs; another one was the high separation efficiency of photogenerated electron–hole pairs due to the trap effect for photogenerated electrons of the interface states between ZQDs and SiO2. During the photocatalytic reaction, the ZQDs-SNTs nanocomposite also exhibited high chemical stability in a wide range of pH values, which might be ascribed to the protective action of SiO2 and the presence of Zn–O–Si bonds between ZQDs and SiO2. Furthermore, the ZQDs-SNTs nanocomposites could be easily recycled because of their one-dimensional nanostructure property.Keywords: degradation; electrospinning; nanocomposite; photocatalysis; SiO2 nanotubes; ZnO quantum dots;

One-dimensional In2O3–TiO2 heteroarchitectures with high visible-light photocatalytic activity have been successfully obtained by a simple combination of electrospinning technique and solvothermal process. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis spectra. The results revealed that the secondary In2O3 nanostructures were successfully grown on the primary TiO2 nanofibers substrates. Compared with the pure TiO2 nanofibers, the obtained In2O3–TiO2 heteroarchitectures showed enhancement of the visible-light photocatalytic activity to degrade rhodamine B (RB) because of the formation of heteroarchitectures, which might improve the separation of photogenerated electrons and holes derived from the coupling effect of TiO2 and In2O3 heteroarchitectures. Moreover, the In2O3–TiO2 heteroarchitectures could be easily recycled without the decrease in the photocatalytic activity because of their one-dimensional nanostructural property.Keywords: degradation; heteroarchitectures; In2O3; photocatalysis; TiO2;

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.

One-dimensional Bi2MoO6/TiO2 hierarchical heterostructures with different secondary Bi2MoO6 nanostructures grown on primary TiO2 nanofibers have been obtained by a combination of electrospinning and a solvothermal technique. The morphology of the secondary Bi2MoO6 nanostructures could be controlled by adjusting the precursor concentration, and then two different morphologies of Bi2MoO6/TiO2 heterostructures with Bi2MoO6 nanoparticles and nanosheets were successfully achieved. Photocatalytic tests displayed that the Bi2MoO6/TiO2 heterostructures possessed a much higher degradation rate of Rhodamine B (RB) than the unmodified TiO2 nanofibers and Bi2MoO6 under UV and visible light. The enhanced photocatalytic activity could be attributed to the extended absorption in the visible light region resulting from the Bi2MoO6 nanosheets, and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Bi2MoO6/TiO2 heterojunction interface. Moreover, the heterostructures could be reclaimed easily by sedimentation without a decrease of the photocatalytic activity.

Core/shell nanofibers of TiO2@carbon embedded by Ag nanoparticles (TiO2@C/Ag NFs) were fabricated by combining the electrospinning technique, the hydrothermal method and an in situreduction approach. The results showed that a uniform graphite carbon layer of approximately 8 nm in thickness was formed around the electrospun TiO2 nanofiber and small Ag nanoparticles (Ag NPs) were dispersed well inside the carbon layer. And, the TiO2@C/Ag NFs had remarkable light absorption in the visible region. The photocatalytic studies revealed that the TiO2@C/Ag NFs exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) and Methyl Orange (MO) compared with the pure TiO2 nanofibers, TiO2@carbon core/shell nanofibers and TiO2/Ag nanofibers under visible light irradiation, which might be attributed to the good light absorption capability and high separation efficiency of photogenerated electron–hole pairs based on the photosynergistic effect among the three components of TiO2, carbon and Ag. And, the TiO2@C/Ag NFs could be easily recycled due to their one-dimensional nanostructural property.

A novel visible photocatalyst of nanostructured 2,9,16,23-tetranitrophthalocyanine copper(II) (CuTNPc) coated on Fe3O4 particles has been successfully fabricated using a simple solvent-thermal process. Scanning electron micrographs (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), were used to characterize the as-synthesized dandelion-like Fe3O4@CuTNPc hierarchical nanostructure. The photocatalytic studies suggested that the dandelion-like Fe3O4@CuTNPc hierarchical nanostructure showed excellent photocatalytic efficiency for the degradation of rhodamine B (RB) and methylene blue (MB) under visible light irradiation. More importantly, the dandelion-like nanostructured Fe3O4@CuTNPc photocatalysts could be effectively separated for reuse by simply applying an external magnetic field. A possible mechanism for the formation of the dandelion-like nanostructured Fe3O4@CuTNPc is suggested.

In the present work, a highly uniform three-dimensional flower-like 2,9,16,23-tetra-nitrophthalocyanine iron (TNFePc) hierarchical nanostructure has been successfully obtained by a facile ethylene glycol solvothermal synthetic route. The as-obtained product was characterized by mass spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), IR spectroscopy, UV-vis spectroscopy, and Brunauer–Emmett–Teller analysis. The results showed that the flower-like hierarchical nanostructure was made up of numerous two-dimensional nanoplates with a thickness of about 50 nm. Electrochemical measurements revealed that the TNFePc hierarchical nanostructure exhibited excellent capacitance behavior, which could be ascribed to the ultrahigh surface area and large pore volume. Finally, a possible mechanism for the formation of three-dimensional flower-like TNFePc was suggested.

Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results indicated that not only were AgNPs (25–50 nm) successfully grown on the CNFs but also the AgNPs were distributed without aggregation on the CNFs. Further more, by adjusting the parameters in hydrothermal processing, the content of silver supported on the CNFs could be easily controlled. The catalytic activities of the CNFs/AgNPs composite nanofibers to the reduction of 4-nitrophenol (4-NP) with NaBH4 were tracked by UV–visible spectroscopy. It was suggested that the CNFs/AgNPs composite nanofibers exhibited high catalytic activity in the reduction of 4-NP, which might be attributed to the high surface areas of AgNPs and synergistic effect on delivery of electrons between CNFs and AgNPs. And, the catalytic efficiency was enhanced with the increasing of the content of silver on the CNFs/AgNPs composite nanofibers. Notably, the CNFs/AgNPs composite nanofibers could be easily recycled due to their one-dimensional nanostructural property.

TiO2@carbon core/shell nanofibers (TiO2@C NFs) with different thinkness of carbon layers (from 2 to 8 nm) were fabricated by combining the electrospinning technique and hydrothermal method. The results showed that a uniform graphite carbon layer was formed around the electrospun TiO2 nanofiber via C–O–Ti bonds. By adjusting the hydrothermal fabrication parameters, the thickness of carbon layer could be easily controlled. Furthermore, the TiO2@C NFs had remarkable light absorption in the visible region. The photocatalytic studies revealed that the TiO2@C NFs exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure TiO2 nanofibers under visible light irradiation, which might be attributed to high separation efficiency of photogenerated electrons and holes based on the synergistic effect between carbon as a sensitizer and TiO2 with one dimension structure. Notably, the TiO2@C NFs could be easily recycled due to their one-dimensional nanostructural property.

One-dimensional ZnO−carbon nanofibers (CNFs) heteroarchitectures with high photocatalytic activity have been successfully obtained by a simple combination of electrospinning technique and hydrothermal process. The as-obtained products were characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and IR spectrum. The results revealed that the secondary ZnO nanostructures were successfully grown on the primary CNFs substrates without aggregation. And, the coverage density of ZnO nanoparticles coating on the surface of the CNFs could be controlled by simply adjusting the mass ratio of zinc acetate to CNFs in the precursor during the hydrothermal process for the fabrication of ZnO−CNFs heterostructures. The obtained ZnO−CNFs heteroarchitectures showed high photocatalytic property to degrade rhodamine B (RB) because of the formation of heteroarchitectures, which might improve the separation of photogenerated electrons and holes. Moreover, the ZnO−CNFs heteroarchitectures could be easily recycled without the decrease in photocatalytic activity due to their one-dimensional nanostructural property.Keywords (keywords): CNFs; degradation; heteroarchitectures; photocatalysis; ZnO

In the present work, 2,9,16,23-tetranitrophthalocyanine copper(II) (TNCuPc)/TiO2 hierarchical nanostructures were successfully fabricated by a simple combination method of electrospinning technique and solvothermal processing. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), UV−vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric and differential thermal analysis (TG-DTA) were used to characterize the as-synthesized TNCuPc/TiO2 hierarchical nanostructures. The results showed that the secondary TNCuPc nanostructures were not only successfully grown on the primary TiO2 nanofibers substrates but also uniformly distributed without aggregation. By adjusting the solvothermal fabrication parameters, the TNCuPc nanowires or nanoflowers were facilely fabricated, and also the loading amounts of TNCuPc could be controlled on the TNCuPc/TiO2 hierarchical nanostructural nanofibers. And, there might exist the interaction between TNCuPc and TiO2. A possible mechanism for the formation of TNCuPc/TiO2 hierarchical nanostructures was suggested. The photocatalytic studies revealed that the TNCuPc/TiO2 hierarchical nanostructures exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure TNCuPc or TiO2 nanofibers under visible-light irradiation.Keywords (keywords): electrospinning; hierarchical nanostructures; photocatalysis; phthalocyanine; solvothermal; TiO2

The tubular nanocomposite with well-dispersed distribution of small gold nanoparticles (AuNPs) assembled on the inside and outside surfaces of silica nanotubes (SNTs) was fabricated by combining the single capillary electrospinning technique and an in situreduction approach. The AuNPs/SNTs nanocomposite exhibited a good catalytic activity for reduction of 4-nitrophenol (4-NP).

The hierarchical tetranitro copper phthalocyanine (TNCuPc) hollow spheres were fabricated by a simple solvothermal method. The formation mechanism was proposed based on the evolution of morphology as a function of solvothermal time, which involved the initial formation of nanoparticles followed by their self-aggregation to microspheres and transformation into hierarchical hollow spheres by Ostwald ripening. Furthermore, the hierarchical TNCuPc hollow spheres exhibited high adsorption capacity and excellent simultaneously visible-light-driven photocatalytic performance for Rhodamine B (RB) under visible light. A possible mechanism for the “aqueous-solid phase transfer and in situ photocatalysis” was suggested. Repetitive tests showed that the hierarchical TNCuPc hollow spheres maintained high catalytic activity over several cycles, and it had a better regeneration capability under mild conditions.Keywords: adsorption; hierarchical; hollow spheres; photocatalysis; phthalocyanine; solvothermal;

Herein, we have demonstrated that the electrospun nanofibers of TiO2/CdS heteroarchitectures could be fabricated through combining electrospinning technique with hydrothermal process. The configuration, crystal structure, and element composition of the as-prepared TiO2/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 TiO2 nanofibers. Especially, the light-absorption properties as well as photocatalytic characteristics of pure TiO2 nanofibers and TiO2/CdS heteroarchitectures with different amount loading of CdS were also investigated. The absorption of TiO2/CdS heteroarchitectures was extended to the visible due to effective immobilization of sensitizing agent CdS on TiO2. In contrast with the pure TiO2 nanofibers, the TiO2/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 TiO2/CdS heteroarchitectures was also discussed.Graphical abstractThe schematic profile depicting the energy band structure and occurrence of vectorial electron transfer in the TiO2/CdS heteroarchitectures.Highlights► The size and content of CdS nanoparticles grown on TiO2 nanofibers are tunable. ► TiO2/CdS nanofibers have higher photocatalytic activity by visible light. ► The electrospinning method combined with hydrothermal process is novel and valuable.

Tin oxide (SnO2)/carbon nanofibers (CNFs) heterostructures were fabricated by combining the versatility of the electrospinning technique and template-free solvent–thermal process. The results revealed that the SnO2 nanostructures were successfully grown on the primary electrospun carbon nanofibers substrates. And, the coverage density of SnO2 nanoparticles coating on the surface of the CNFs could be controlled by simply adjusting the mass ratio of CNFs to SnCl4·5H2O in the precursor during the solvent–thermal process for the fabrication of SnO2/CNFs heterostructures. The electrochemical performances of the SnO2/CNFs heterostructures as the electrode materials for supercapacitors were evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge measurement in 1 M H2SO4 solution. At different scan rates, all the samples with different coverage densities of SnO2 showed excellent capacitance behavior. And, the sample CS2 (the mass ratio of CNFs to SnCl4·5H2O reached 1:7) exhibited a maximum specific capacitance of 187 F/g at a scan rate of 20 mV/s. Moreover, after 1000 cycles, the specific capacitance retention of this sample was over 95%. The high capacitive behavior could be ascribed to the low resistance of SnO2/CNFs heterostructures and rapid transport of the electrolyte ions from bulk solution to the surface of SnO2.Graphical abstractThe SnO2/CNFs heteroarchitectures are successfully fabricated by combining the electrospinning technique and the hydrothermal method showing high capacitive behavior as the electrode materials for supercapacitors.Research highlights► Easy synthesis of SnO2/CNFs heteroarchitectures. ► Controllable SnO2 nanoparticles on the surfaces of the CNFs. ► The SnO2/CNFs heterostructures possess excellent capacitive performance.

The Ag2S nanoparticles embedded in polyacrylonitrile (PAN) fibers matrix were successfully prepared by the combining electrospinning with the hydro(solvo)thermal process, without the presence of any templates or organic surfactants. What's more, the size and content of Ag2S nanoparticles was tunable through proper controlling of the reaction conditions. Consequently, the Ag2S nanoparticles with 10–100 nm diameter could be obtained via this two-step synthetic route. The as-synthesized composites nanofibers were investigated by X-ray diffraction(XRD), field-emission scanning electronic microscopy (FE-SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence( PL), respectively. What's more, a possible formation mechanism of Ag2S nanoparticles grown on PAN nanofibers was also proposed.Research Highlights► The size and content of Ag2S nanoparticles embedded in PAN nanofibers was tunable. ► PAN/Ag2S nanofibers would be a kind of prospective optoelectronic material. ► The electrospinning method coupled with hydrothermal process is novel and simple.

One-dimensional electrospun nanofibers of p-type NiO/n-type ZnO heterojunctions with different molar ratios of Ni to Zn were successfully synthesized using a facile electrospinning technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV−vis diffuse reflectance (DR) spectroscopy, resonant Raman spectroscopy, photoluminescence (PL) spectroscopy, and surface photovoltage spectroscopy (SPS) were used to characterize the as-synthesized nanofibers. The results indicated that the p−n heterojunctions formed between the cubic structure NiO and hexangular structure ZnO in the NiO/ZnO nanofibers. Furthermore, the photocatalytic activity of the as-electrospun NiO/ZnO nanofibers for the degradation of rhodamine B (RB) was much higher than that of electrospun NiO and ZnO nanofibers, which could be ascribed to the formation of p−n heterojunctions in the NiO/ZnO nanofibers. In particular, the p-type NiO/n-type ZnO heterojunction nanofibers with the original Ni/Zn molar ratio of 1 exhibited the best catalytic activity, which might be attributed to their high separation efficiency of photogenerated electrons and holes. Notably, the electrospun nanofibers of p-type NiO/n-type ZnO heterojunctions could be easily recycled without a decrease of the photocatalytic activity due to their one-dimensional nanostructural property.Keywords: electrospinning; heterojunction; nanofibers; NiO; photocatalysis; ZnO

In this work, V-doped TiO2 nanofibers with different V contents have been fabricated by an electrospinning technique. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), and UV–Vis diffuse reflectance (DR) spectroscopy. The results indicated that the V4+ or V5+ ions were successfully incorporated into the crystal lattice of anatase TiO2 nanofibers. Meanwhile, the V doping could extend the visible light absorption of TiO2 nanofibers. The photocatalytic experiments indicated that the obtained V-doped TiO2 nanofibers possessed high activity for the photodegradation of organic pollutant methylene blue (MB). Especially, the 1.0 and 5.0 wt.% V-doped TiO2 nanofibers exhibited the best catalytic activity under visible and ultraviolet (UV) light irradiation, respectively. Also, these nanofibers could be easily recycled without a decrease of the photocatalytic activity.V-doped TiO2 nanofibers with different V content have been fabricated by electrospinning technique. The obtained V-doped TiO2 nanofibers exhibited high activity for the photodegradation of organic pollutants methylene blue.

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.From panoramic FESEM image of TiO2/PbS heteroarchitectures obtained via hydrothermal treatment, we can see that PbS nanocubes are closely attached to TiO2 nanofibres.

Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.

Nanofibers of poly(acrylonitrile)/Eu3+ were prepared by using sol–gel processing and electrospinning technique. The diameter of the nanofibers in the non-woven membranes was about 70–100 nm. The nanofibers were characterized by scanning electron microscopy (SEM), fourier transform infrared (FT-IR), and photoluminescence (PL). In our work, the PAN/Eu3+ hybrid nanofibers showed excellent photoluminescence properties. A possible PL mechanism was proposed accordingly. It is expected that these kind of materials would be applied in equipments such as optoelectronic nanodevices in the future.

One-dimensional ZnO−SnO2 nanofibers with high photocatalytic activity have been successfully synthesized by a simple combination method of sol−gel process and electrospinning technique. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, nitrogen adsorption−desorption isotherm analysis, UV−vis diffuse reflectance (DR), and photoluminescence (PL) spectroscopy were used to characterize the as-synthesized nanofibers. The results indicated that the ZnO−SnO2 nanofibers with diameters of 100−150 nm consisted of wurtzite ZnO and rutile SnO2. The photocatalytic activity of the ZnO−SnO2 nanofibers for the degradation of rhodamine B (RB) was much higher than that of electrospun ZnO and SnO2 nanofibers, which could be attributed to the formation of a ZnO−SnO2 heterojunction in the ZnO−SnO2 nanofibers and the high specific surface area of the ZnO−SnO2 nanofibers. Notably, the ZnO−SnO2 nanofibers could be easily recycled without the decrease of the photocatalytic activity due to their one-dimensional nanostructural property.

Composite nanofibers with a weight ratio of 30%NiO–70%SiO2 and diameters ranging from 80 to 100 nm were successfully prepared by electrospinning a precursor mixture of polyvinyl alcohol (PVA)/silica/nickel acetate followed by calcination treatment of the electrospun polymer/inorganic composite fibers. The resulting NiO/SiO2 composite nanofibers were characterized by TG-DTA, FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy . The results revealed that the crystalline phase of NiO nanoparticles were formed at a temperature higher than 600 °C. The SEM results show that the morphology of the fibers is affected greatly by the calcination temperature.

In this work, ZnO hollow nanofibers with diameters of 120−150 nm were successfully fabricated by electrospinning the precursor solution consisting of polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and zinc acetate composite through a facile single capillary, followed by thermal decomposition for removal of the above polymers from the precursor fibers. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), resonant Raman spectra, thermal gravimetric and differential thermal analysis (TG-DTA), and Fourier transform infrared spectroscopy (FT-IR) spectra, respectively. The results indicated that, during the electrospinning process, there occurred phase separation between the electrospun composite materials, while the obtained precursor nanofibers of PAN, PVP, and zinc acetate composite might possess a core−shell structure (PAN as the core and PVP/zinc acetate composite as the shell). Furthermore, the composite nanofibers with core/shell structure could play a structural directing template role for preparing ZnO hollow nanofibers during the calcination process. The ZnO hollow nanofibers exhibited excellent sensing properties against ethanol due to their special one-dimensional nanostructural properties.

•BiOCl nanosheets exposing {001} facets were uniformly grown on TiO2 nanofibers.•The p–n heterostructures exhibited enhanced UV-light photocatalytic activity.•The composites could be recycled easily due to nonwoven nanofibrous structures.Hierarchical heterostructures of p-type BiOCl nanosheets/n-type TiO2 nanofibers (p-BiOCl/n-TiO2 HHs) were prepared by combining the electrospinning technique and solvothermal method. BiOCl nanosheets with exposed {001} facets were densely and uniformly grown on the electrospun TiO2 nanofibers. The obtained p-BiOCl/n-TiO2 HHs exhibited enhanced UV-light photocatalytic activity due to the effects of p-n heterojunctions and high surface areas. Experiments proved that the generation rate of hydroxyl radicals for p-BiOCl/n-TiO2 HHs was much larger than that of TiO2 nanofibers. Moreover, the p-BiOCl/n-TiO2 HHs could be recycled easily by sedimentation because of their nanofibrous nonwoven web structure.p-BiOCl/n-TiO2 HHs exhibit enhanced photocatalytic activity due to the p-n heterojunction effects, large surface areas, and more active surface reaction sites.Download full-size image

A novel photocatalyst of nanostructured cadmium phthalocyanine (CdPc) immobilized on the surface of polyacrylonitrile (PAN) nanofibers had been successfully fabricated by a simple combination of electrospinning technique and the solvent-thermal process. FE-SEM micrographs indicated that the nanostructured CdPc uniformly immobilized on the surface of PAN nanofibers without agglomeration. And the obtained CdPc/PAN composite nanofibers exhibited high visible light photocatalytic activity for the degradation of rhodamine B. Moreover, this photocatalyst could be easily separated for reuse due to the one-dimensional nanostructural property of the CdPc/PAN composite nanofibers.The different morphologies of cadmium phthalocyanine (CdPc) nanostructures immobilized on the polyacrylonitrile (PAN) nanofibers uniformly. And, the CdPc/PAN composite nanofibers photocatalysts with high photocatalytic activity could be easily separated and reused.Download full-size imageResearch Highlights► Synthesis of CdPc/PAN composite nanofibers are rare in the literature. ► Controllable CdPc nanostructures immobilized on the PAN nanofibers uniformly. ► CdPc/PAN photocatalyst have high visible light photocatalytic activity. ► Easy photocatalyst separation and reuse.

•Synthesis of In2S3/CNFs/Au ternary synergetic system.•Enhanced visible-light photocatalytic activity.•Easy photocatalyst separation and reuse.In this paper, carbon nanofibers (CNFs) were successfully synthesized by electrospinning technique. Next, Au nanoparticles (NPs) were assembled on the electrospun CNFs through in situ reduction method. By using the obtained Au NPs modified CNFs (CNFs/Au) as hard template, the In2S3/CNFs/Au composites were synthesized through hydrothermal technique. The results showed that the super long one-dimensional (1D) CNFs (about 306 nm in average diameter) were well connected to form a nanofibrous network; and, the Au NPs with 18 nm in average diameter and In2S3 nanosheets with 5–10 nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In2S3/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In2S3 and In2S3/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron–hole pairs based on the positive synergetic effect between In2S3, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In2S3/CNFs/Au composites with hierarchical structure possess a strong adsorption ability towards organic dyes, which also contributed to the enhancement of photocatalytic activity. Moreover, the In2S3/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure.We describe a route to synthesize In2S3/CNFs/Au ternary synergetic system with high efficiency visible-light photocatalytic activity.Download full-size image

We highlight a hydrothermal synthetic approach at low temperatures to prepare carbon-rich graphitic carbon nitride nanosheets, which show enhanced photocurrent and photocatalytic activity, due to their improved electron transport ability along the in-plane direction and increased lifetime of photoexcited charge carriers.

One-dimensional In2O3 nanocubes/carbon nanofibers (CNFs) heterostructures have been successfully obtained by a simple combination of electrospinning technique and solvothermal process for the first time. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and IR spectra. The results revealed that the secondary In2O3 nanocubes were successfully grown on the primary CNF substrates. Photocatalytic tests displayed that the In2O3/CNFs heterostructures possessed a much higher degradation rate of rhodamine B (RB) than the pure In2O3 under visible light. The enhanced photocatalytic activity could be attributed to the formation of heterostructures, which might improve the separation of photogenerated electrons and holes. Moreover, the In2O3/CNF heterostructures could be easily recycled without the decrease of the photocatalytic activity due to their one-dimensional nanostructural property. The morphology of the secondary In2O3 nanostructures (nanocubes, nanoagglomerates or nanoparticles) could be controlled by adjusting the additives including CO(NH2)2 and a defined amount of water. The general growth mechanisms for the In2O3 nanostructures have also been discussed.

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.

Core/shell nanofibers of TiO2@carbon embedded by Ag nanoparticles (TiO2@C/Ag NFs) were fabricated by combining the electrospinning technique, the hydrothermal method and an in situreduction approach. The results showed that a uniform graphite carbon layer of approximately 8 nm in thickness was formed around the electrospun TiO2 nanofiber and small Ag nanoparticles (Ag NPs) were dispersed well inside the carbon layer. And, the TiO2@C/Ag NFs had remarkable light absorption in the visible region. The photocatalytic studies revealed that the TiO2@C/Ag NFs exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) and Methyl Orange (MO) compared with the pure TiO2 nanofibers, TiO2@carbon core/shell nanofibers and TiO2/Ag nanofibers under visible light irradiation, which might be attributed to the good light absorption capability and high separation efficiency of photogenerated electron–hole pairs based on the photosynergistic effect among the three components of TiO2, carbon and Ag. And, the TiO2@C/Ag NFs could be easily recycled due to their one-dimensional nanostructural property.

Tubular nanocomposites of silver nanoparticles (AgNPs)/silica nanotubes (SNTs) with the nearly uniform diameters of 250–350 nm were successfully fabricated by combining the single capillary electrospinning technique (for SNTs as the supports) and an in situreduction approach (for AgNPs). The highly dispersed AgNPs assembled on the inner and outer surface of SNTs through the in situreduction of Ag+ by Sn2+ ions were confirmed by transmission electron microscopy (TEM), UV-Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). It was interesting to note that the size of AgNPs on the surface of SNTs could be controlled by appropriately adjusting the amount of ammonia solution during the above in situreduction reaction. The catalytic activities of the as-prepared tubular nanocomposites were evaluated by using a model reaction based on the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH4 as the reductant. The results indicated that all the tubular nanocomposites catalysts with high specific surface area (185–250 m2 g−1) exhibited excellent catalytic activities because the highly dispersed AgNPs were exposed on the inner and outer surface of electrospun SNTs, allowing effective contact with the reactants and catalysis of the reaction. In particular, the tubular nanocomposite catalysts containing small size AgNPs had higher catalytic activities than those containing the large size ones, which was attributed to the size-dependent Ag redox potential and surface-to-volume ratio influencing interfacial electron transfer from AgNPs surface to 4-NP in the presence of highly electron injecting BH4− ions. Those tubular catalysts based on AgNPs/SNTs nanocomposites could be easily recycled without a decrease of the catalytic activities due to their one-dimensional nanostructural property.

Recently, hierarchically porous carbon materials with advantages of hierarchical porosity and large specific surface areas exhibiting desirable capacitive performance have been widely investigated. Herein, a facile and template-free phase separation methodology has been presented to prepare three-dimensional freestanding hierarchically porous carbon (HPC) materials. Importantly, the as-fabricated HPC with highly uniform and well-interconnected pores can afford plentiful transport channels for rapid diffusion of more ions, and the highly conductive cross-linked backbones ensure fast electron transfer, both of which can greatly reduce the internal resistance and improve the electrochemical properties. As expected, the as-fabricated HPC-based supercapacitor has achieved outstanding electrochemical performance with a high cell capacitance of 51 F g−1 at a current density of 0.5 A g−1, good rate capability with 75% capacitance retention of initial capacitance at 32 A g−1 as well as a maximum energy density of 4.5 W h kg−1 at 200 W kg−1 and a maximum power density of 15100 W kg−1 at 3.4 W h kg−1. More significantly, a remarkable cycling stability almost without capacitance loss after the 50000 charge/discharge test at 5 A g−1 has been achieved for the HPC-based supercapacitors. All these results suggest that the as-synthesized HPC has great potential for application not only as a supercapacitor electrode but also as a substrate for supporting capacitive materials.

The tubular nanocomposite with well-dispersed distribution of small gold nanoparticles (AuNPs) assembled on the inside and outside surfaces of silica nanotubes (SNTs) was fabricated by combining the single capillary electrospinning technique and an in situreduction approach. The AuNPs/SNTs nanocomposite exhibited a good catalytic activity for reduction of 4-nitrophenol (4-NP).

A novel visible photocatalyst of nanostructured 2,9,16,23-tetranitrophthalocyanine copper(II) (CuTNPc) coated on Fe3O4 particles has been successfully fabricated using a simple solvent-thermal process. Scanning electron micrographs (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), were used to characterize the as-synthesized dandelion-like Fe3O4@CuTNPc hierarchical nanostructure. The photocatalytic studies suggested that the dandelion-like Fe3O4@CuTNPc hierarchical nanostructure showed excellent photocatalytic efficiency for the degradation of rhodamine B (RB) and methylene blue (MB) under visible light irradiation. More importantly, the dandelion-like nanostructured Fe3O4@CuTNPc photocatalysts could be effectively separated for reuse by simply applying an external magnetic field. A possible mechanism for the formation of the dandelion-like nanostructured Fe3O4@CuTNPc is suggested.

Freestanding nitrogen-doped porous carbon nanofibers (NPCNFs) are prepared by carbonizing the nitrogen-enriched porous binary polymer precursors of electrospun polyacrylonitrile/polyaniline core–shell composite nanofibers at an appropriate temperature. The obtained freestanding NPCNFs with the advantages of a suitable nitrogen content, hierarchical porosity, large specific surface areas, and good conductivity are very promising to achieve desirable electrochemical performance. As expected, the NPCNFs as electrode materials demonstrate a high specific capacitance of 335 F g−1 at a current density of 0.5 A g−1 and high rate capability with a capacitance retention of 175 F g−1 at 32 A g−1 in a three-electrode configuration test. Particularly, the as-fabricated flexible solid-state supercapacitor based on the freestanding NPCNFs delivers a maximum energy density of 9.2 W h kg−1 at 0.25 kW kg−1 and also presents good cycling stability with 86% capacitance retention after 10000 cycles at a current density of 5 A g−1. Therefore, the freestanding NPCNFs as electrode materials for flexible solid-state supercapacitors might have potential applications in portable and flexible electronics.