Changlu Shao

Electrospun Nanofibers of p-Type NiO/n-Type ZnO Heterojunctions with Enhanced Photocatalytic Activity

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.

High photocatalytic activity of ZnO-carbon nanofiber heteroarchitectures.

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.

In situ assembly of well-dispersed gold nanoparticles on electrospun silica nanotubes for catalytic reduction of 4-nitrophenol

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 situ reduction approach. The AuNPs/SNTs nanocomposite exhibited a good catalytic activity for reduction of 4-nitrophenol (4-NP).

SnO2 Nanostructures-TiO2 Nanofibers Heterostructures: Controlled Fabrication and High Photocatalytic Properties

Combining the versatility of the electrospinning technique and hydrothermal growth of nanostructures enabled the fabrication of hierarchical SnO(2)/TiO(2) composite nanostructures. The results revealed that not only were secondary SnO(2) nanostructures successfully grown on primary TiO(2) nanofiber substrates but also the SnO(2) nanostructures were uniformly distributed without aggregation on TiO(2) nanofibers. By adjusting fabrication parameters, the morphology as well as coverage density of secondary SnO(2) nanostructures could be further controlled, and then SnO(2)/TiO(2) heterostructures with SnO(2) nanoparticles or nanorods were facilely fabricated. The photocatalytic studies suggested that the SnO(2)/TiO(2) heterostructures showed enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the bare TiO(2) nanofibers under UV light irradiation.

A Facile in Situ Hydrothermal Method to SrTiO3/TiO2 Nanofiber Heterostructures with High Photocatalytic Activity

Heterostructured SrTiO3/TiO2 nanofibers were fabricated by in situ hydrothermal method using TiO2 nanofibers as both template and reactant. The as-fabricated heterostructures composite included SrTiO3 nanocubes or nanoparticles assembled uniformly on the surface of TiO2 nanofibers. Compared with the pure TiO2 nanofibers, SrTiO3/TiO2 nanofibers exhibited enhanced photocatalytic activity in the decomposition of Rhodamine B (RB) under ultraviolet light. The enhanced photocatalytic activity of SrTiO3/TiO2 nanofibers could be attributed to the improvement of charge separation derived from the coupling effect of TiO2 and SrTiO3 nanocomposite.

Highly dispersed Fe3O4 nanosheets on one-dimensional carbon nanofibers: Synthesis, formation mechanism, and electrochemical performance as supercapacitor electrode materials

Highly dispersed Fe3O4 nanosheets on one-dimensional (1D) carbon nanofibers (CNFs) were firstly fabricated by combining the versatility of the electrospinning technique and solvent-thermal process. The electrochemical performances of the Fe3O4/CNFs nanocomposites as the electrode materials for supercapacitors were evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge measurement in 1 M Na2SO3 electrolyte. At different scan rates, the sample showed excellent capacitance behavior. The high capacitive behavior could be ascribed to the high electrical conductivity and the one-dimensional properties of the CNFs in Fe3O4/CNFs nanocomposites, which could decrease the charge transfer resistance of the Fe3O4. At the same time, the high specific surface area and high level exposure of the Fe3O4 nanosheets on the surface of the CNFs increased the electrochemical utilization of Fe3O4. Moreover, in comparison to the pure Fe3O4 (83 F g−1), the as-prepared Fe3O4/CNFs nanocomposites electrode exhibited a higher specific capacitance (135 F g−1). Meanwhile, the supercapacitor devices of the Fe3O4/CNFs nanocomposites exhibited excellent long cycle life along with 91% specific capacitance retained after 1000 cycle tests. Finally, a possible mechanism for the formation of the Fe3O4 nanosheets on the surface of CNFs was suggested.

Tubular nanocomposite catalysts based on size-controlled and highly dispersed silver nanoparticles assembled on electrospun silica nanotubes for catalytic reduction of 4-nitrophenol

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.

Enhancement of the visible-light photocatalytic activity of In2O3-TiO2 nanofiber heteroarchitectures.

One-dimensional In(2)O(3)-TiO(2) 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 In(2)O(3) nanostructures were successfully grown on the primary TiO(2) nanofibers substrates. Compared with the pure TiO(2) nanofibers, the obtained In(2)O(3)-TiO(2) 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 TiO(2) and In(2)O(3) heteroarchitectures. Moreover, the In(2)O(3)-TiO(2) heteroarchitectures could be easily recycled without the decrease in the photocatalytic activity because of their one-dimensional nanostructural property.

One-dimensional Bi2MoO6/TiO2 hierarchical heterostructures with enhanced photocatalytic activity

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.

Hierarchical heterostructures of Bi2MoO6 on carbon nanofibers: controllable solvothermal fabrication and enhanced visible photocatalytic properties

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.