Feng-Jun Zhang

Synthesis, characterization, and photocatalytic analysis of CNT/TiO2 composites derived from MWCNTs and titanium sources

Abstract CNT/TiO 2 composites were prepared using multi-walled carbon nanotubes (MWCNTs) as a starting material, and titanium(IV) isopropoxide, titanium(IV) propoxide and titanium(IV) n -butoxide as titanium sources and benzene as a solvent. The composites were characterized by N 2 adsorption, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray analysis, and UV-vis absorption spectroscopy. The photoactivity of the prepared materials was evaluated by the conversion of methylene blue (MB, C 16 H 18 N 3 S·Cl·3H 2 O) in aqueous solution under UV irradiation. It can be found that the MB removal effect of the CNT/TiO 2 composites is not only due to the adsorption of MWCNTs and the photocatalytic degradation of TiO 2 but also to electron transfer between MWCNTs and TiO 2 .

Rapid sonochemical synthesis of irregular nanolaminar-like Bi2WO6 as efficient visible-light-active photocatalysts

Irregular Bi(2)WO(6) nanolaminars have been successfully synthesized via a rapid sonochemical approach using bismuth nitrate and tungstic acid as precursors in an aqueous solution. The characteristics of them were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N(2) adsorption, pore value, PL spectroscopy and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). These irregular nanolaminars are of geometric shapes of orthorhombic Bi(2)WO(6) with their basal plane being (001). They possess high crystallinity, lager surface area and pore value, which means fewer traps and stronger photocatalytic activity. The growth mechanism of such special nanolaminar was related to the sonochemical synthesis route, which played a key role in the formation of Bi(2)WO(6) nanolaminar. Simultaneously, it was found that the formation of Bi(2)WO(6) nanolaminar is a time dependent process. The Bi(2)WO(6) nanolaminar has higher photocatalytic activity than bulk Bi(2)WO(6) nanoparticle obtained by refluxing method for rhodamine B (Rh.B) degradation under visible light irradiation (λ>400 nm).

Photoelectrocatalytic Properties of Ag-CNT/TiO2 Composite Electrodes for Methylene Blue Degradation

Carbon nanotubes modified with silver (Ag-CNTs) were used for the fabrication of Ag-CNT/TiO2 composite electrodes. The electrodes were characterized by X-ray diffraction, transmission and scanning electron microscopy, and energy dispersive X-ray analysis. It was found that TiO2 particles were distributed uniformly in the CNT networks, and silver particles were fixed on the surface of the CNTs.. The composite electrodes exhibited a high photoelectrocatalytic (PEC) activity. The PEC degradation efficiency for methylene blue (MB) was a synergistic effect of photo-degradation of TiO2, increased electrical conductivity by the CNT networks, an effect of the silver and a function of the applied potential. Especially, the composites treated with silver revealed an enhanced photo-degradation ability for MB and the PEC activity increased with increasing silver content.

A novel and simple approach for the synthesis of Fe3O4-graphene composite

High crystalline Fe3O4-graphene composite has been successfully synthesized via one-step thermolysis reaction. The results demonstrated that the attachment of iron-organic complex with graphene oxide sheets can facilely lead to magnetic graphene composites with a time-dependent calcination process. The composite was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The high efficient removal of methylene blue determined that Fe3O4-graphene is a promising sorbent material for wastewater treatment.

Characterization of Graphene Nanosheets as Electrode Material and Their Performances for Electric Double-Layer Capacitors

In this work, graphene nanosheets were prepared using the Hummers-Offeman method. We prepared the resultant graphene electrode with kneading type. The prepared graphene nanosheets were characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy instrument and Raman spectra. Finally, the electrochemical performances of graphene nanosheets in an electrolyte solution of tetraethylammonium tetrafluoroborate ((C2H5)4NBF4, TEABF4) in propylene carbonate (C4H6O3, PC) were examined.

Photocatalytic Degradation of Methyl Orange on Platinum and Palladium Co-doped TiO2 Nanoparticles

Pt and Pd co-doped TiO2 nanoparticles were synthesized using modified sol-gel processes and characterized by BET surface area, SEM, TEM, XRD, EDX, FT-IR, and UV-Vis spectroscopy. The results showed that the Pt/Pd-TiO2 nanoparticles possess high surface area and small particles size compared with individual Pt or Pd doped TiO2. The significantly high photocatalytic activity can be ascribed to the simultaneous effects of doped Pt and Pd by cascadal electron transfer from TiO2 to Pd to Pt and reach surface excitation state. And the optimum molar ratio of Pt/Pd at 1.5 can effectively reduce the electron–hole recombination rate.

Enhanced photocatalytic activity by the tunnel effect of microstructured InVO4/WO3 heterojunctions

Microstructured InVO4/WO3 heterojunctions were fabricated by a facile hydrothermal method and investigated in the photocatalytic degradation of rhodamine B (Rh.B) under simulated solar light. Embedding InVO4 into microhollow WO3 demonstrated efficient charge separation at the interface in essence. An interesting synergetic effect between InVO4 and WO3 led to an improved photocatalytic performance. However, the dropping of photoelectrochemical properties was tentatively deduced in the mechanism of charge recombination between electrons generated from WO3 and holes from InVO4. The tunnel effect has promoted the formation of electron/hole pairs with high redox potentials. However, it reduced the number of electrons to some extent.

UV and visible light photodegradation effect on Fe–CNT/TiO2 composite catalysts

Using multi-walled carbon nanotube (CNT) as an one-dimensional support, we have succeeded in uniformly anchoring of TiO2 and Fe nanoparticles at its surface. The as-prepared Fe–CNT/TiO2 composite photocatalysts have been investigated by degrading methylene blue (MB) under UV and differently intensified visible light irradiation. The ability of CNT to store and shuttle electrons, and Fe nanoparticles demonstrate its capability to serve as a yield and transfer electrons on demand to separate h + /e −  pairs. Moreover, the MB photodegradation increase with an increase of visible light intensity can be ascribed to the enhancement MB cationic radical. In addition, chemical oxygen demand (COD) of piggery waste and reduction efficiency of Cr (IV) was done at regular intervals, which gave a good idea about mineralization of wastewater.