Photoelectrocatalytic Degradation of Dyes in Aqueous Solution Using CNT/TiO₂ Electrode

Feng-Jun Zhang,Jin Liu,Ming-Liang Chen,Won-Chun Oh 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3

The effect of photoelectrocatalytic (PEC) degradation for different dyes with the CNT/TiO₂ electrode was studied. The prepared electrode was characterized with surface properties, structural crystallinity, elemental identification, and PEC activity. The N2 adsorption data showed that the composites had decreased surface area compared with the pristine CNT. This indicated the blocking of micropores on the surface of CNT, which was further supported by observation via FESEM. XRD patterns of the composites showed that the CNT/TiO₂ composite contained a mixing anatase and rutile phase. EDX spectra showed the presence of C, O and Ti peaks for all samples. The decomposition efifciency of the prepared electrode was evaluated by the PEC degradation of three dyes (methylene blue (MB), rhodamine B (RH.B), methyl orange (MO)). The variations of the FT-IR spectra and pH value of dye solutions were measured during the PEC system; it was found that the CNT/ TiO₂ electrode has better PEC degradation for MB solution than that of RH.B and MO. The proposed degradation mechanism was present.

Effects of stiffening rings on the dynamic properties of hyperboloidal cooling towers

Jun-Feng Zhang,Huai Chen,Yao-Jun Ge,Lin Zhao,Shi-Tang Ke 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

As hyperboloidal cooling towers (HCTs) growing larger and slender, they become more sensitive to gust wind. To improve the dynamic properties of HCTs and to improve the wind resistance capability, stiffening rings have been studied and applied. Although there have been some findings, the influence mechanism of stiffening rings on the dynamic properties is still not fully understood. Based on some fundamental perceptions on the dynamic properties of HCTs and free ring structures, a concept named “participation degree” of stiffening rings was proposed and the influence mechanism on the dynamic properties was illustrated. The “participation degree” is determined by the modal deform amplitude and latitude wave number of stiffening rings. Larger modal deform amplitude and more latitude waves can both result in higher participation degree and more improvement to eigenfrequencies. Also, this concept can explain and associate the pre-existing independent findings.

Formation of Magnetic Graphene Nanosheets for Rapid Enrichment and Separation of Methyl Orange from Water

Zhang, Feng-Jun,Zhang, Zhuo,Xie, Fa-Zhi,Xuan, Han,Xia, Hong-Chen,Zhu, Lei,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.6

Magnetic-graphene nanosheets have been synthesized via a simple effective chemical precipitation method followed by heat treatment. The composite nanosheets are super paramagnetic at room temperature and can be separated by an external magnetic field. The prepared magnetic-graphene nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and BET surface area analysis. The results demonstrated the successful attachment of iron oxide nanoparticles to graphene nanosheets. It was found that the attached nanoparticles were mainly $Fe_3O_4$. The magnetic-graphene nanosheets showed near complete methyl orange removal within 10 mintues and would be practically usable for methyl orange separation from water.

Influence of latitude wind pressure distribution on the responses of hyperbolodial cooling tower shell

Jun-Feng Zhang,Yao-Jun Ge,Lin Zhao 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.6

Interference effects are of considerable concern for group hyperboloidal cooling towers, but evaluation methods and results are different from each other because of the insufficient understanding on the structure behavior. Therefore, the mechanical performance of hyperboloidal cooling tower shell under wind loads was illustrated according to some basic properties drawn from horizontal rings and cantilever beams. The hyperboloidal cooling tower shell can be regarded as the coupling of horizontal rings and meridian cantilever beams, and this perception is beneficial for understanding the mechanical performance under wind loads. Afterwards, the mean external latitude wind pressure distribution, CP(θ), was artificially adjusted to pursue the relationship between different CP(θ) and wind-induced responses. It was found that the maximum responses in hyperboloidal cooling tower shell are primarily dominated by the non-uniformity of CP(θ) but not the local pressure amplitude CP or overall resistance/drag coefficient CD. In all the internal forces, the maximum amplitude of meridian axial tension shows remarkable sensitivity to the variation of CP(θ) and it’s also the controlling force in structure design, so it was selected as an indicator to evaluate the influence of CP(θ) on responses. Based on its sensitivity to different adjustment parameters of CP(θ), an comprehensive response influence factor, RIF, was deduced to assess the meridian axial tension for arbitrary CP(θ).

Synthesis and characterization of polysilane with double bonds by an electrochemical method

Feng-Jun Zhang,Ming-Liang Chen,Lai Chen,Shi Wu,오원춘 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Polysilanes with double bonds have been synthesized by the electroreduction of trichloromethylsilane and allyl chloride in a single compartment cell. The polymers have been characterized using FTIR, GPC and 1H NMR. The effects of monomer ratio, monomer concentration, electrode materials, the electrode’s interval time and the amount of electricity supplied were investigated. The results indicate that the ideal molar ratio of MeSiCl3/allyl chloride is 3:1 with a Mg electrode material. The molecular weight and yield of polysilanes became higher with an increase of the charge passed, a shortening of the electrode’s interval time, and a decrease of the monomer concentration.

Fabrication and Electro-photolysis Property of Carbon Nanotubes/Titanium Composite Photocatalysts for Methylene Blue

Zhang, Feng-Jun,Chen, Ming-Liang,Oh, Won-Chun Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.8

In this study, we have studied on improved performance of carbon nanotubes/titanium (CNT/TiO2) structure electrode for methylene blue (MB). The composite electrodes consisting of CNTs and a titanium oxide matrix with phenol resin binder was fabricated with a mixture method. The chemical and morphological structure of CNT/Ti$O_2$ composites were characterized by means of BET surface area, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis absorption technique, Raman spectroscopy and energy dispersive X-ray (EDX). The electrode showed a remarkably enhanced performance for MB oxidation under UV illumination with or without electro-chemical reaction (ECR). Such a remarkably improved performance of the CNT/Ti$O_2$ structure electrode might be due to the enhanced MB oxidation by electro- and photo-generated electrons and holes in the CNTs and Ti$O_2$ under UV illumination with or without ECR.

Synthesis and Characterization of MoS₂/Graphene-TiO₂ Ternary Photocatalysts for High-Efficiency Hydrogen Production under Visible Light

Zhang, Feng-Jun,Kong, Cui,Li, Xuan,Sun, Xian-Yang,Xie, Wen-Jie,Oh, Won-Chun The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.3

Ternary MoS₂/graphene (G)-TiO₂ photocatalysts were prepared by a simple hydrothermal method. The morphology, phase structure, band gap, and catalytic properties of the prepared samples were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-vis spectrophotometry, and Brunauer-Emmett-Teller surface area measurement. The H₂ production efficiency of the prepared catalysts was tested in methanol-water mixture under visible light. MoS₂/G-TiO₂ exhibited the highest activity for photocatalytic H₂ production. For 5 wt.% and 1 wt.% MoS₂ and graphene (5MT-1G), the production rate of H₂ was as high as 1989 µmol^-1h^-1. The catalyst 5MT-1G showed H₂ production activity that was ~ 11.3, 5.6, and 4.1 times higher than those of pure TiO₂, 1GT, and 5MT, respectively. The unique structure and morphology of the MoS₂/G-TiO₂ photocatalyst contributed to its improved hydrogen production efficiency under visible light.

Synthesis and Characterization of CNT / TiO₂ Photoelectrocatalytic Electrodes for Methlene Blue Degradation

Zhang, Feng-Jun,Chen, Ming-Liang,Oh, Won-Chun Materials Research Society of Korea 2008 한국재료학회지 Vol.18 No.11

In this study, two series of CNT/$TiO_2$ electrodes were prepared. The decrease of surface area compared with that of the pristine carbon nanotubes (CNTs) indicated the blocking of micropores on the surface of the CNTs; was further supported by scanning electron microscopy (SEM) and field emission SEM (FE-SEM) observations. The X-ray diffraction (XRD) results showed that the CNT/$TiO_2$ composites contained a mix of anatase and rutile forms of $TiO_2$ particles when the precursor was $TiO_2$ powder, whereas when the precursor was Ti ($OC_4H_7$) (TNB), the composites contained only the typical single and clear anatase $TiO_2$ particles. The energy dispersive X-ray spectroscopy (EDX) spectra showed the presence of C, O and Ti peaks for all samples. It was found that catalytic decomposition of methylene blue (MB) solution could be attributed to synthetic effects between the $TiO_2$ photocatalysis and electro-assisted CNTs network, and that photoelectrocatalytic oxidation increased with an increase of CNT composition. It was also found that the photoelectrocatalytic oxidation efficiency for MB is higher than that of photocatalytic oxidation. Moreover, the CNT/$TiO_2$ composites catalyst prepared by the impregnation method demonstrates higher photoelectrocatalytic activity than the mechanical mixture with the same CNT content.

Electrochemical Preparation of TiO₂/CNT Electrodes with a TNB Electrolyte and Their Photoelectrocatalytic Effects

Zhang, Feng-Jun,Chen, Ming-Liang,Oh, Won-Chun The Korean Ceramic Society 2009 한국세라믹학회지 Vol.46 No.4

We investigate a method for the electrochemical preparation of titanium dioxide/carbon nanotube ($TiO_2$/CNT) composites involving the electroplating of Ti in a titanium n-butoxide (TNB) electrolyte into a CNT matrix. The BET surface areas of $TiO_2$/CNT composites decreased as electrochemical operating time increased. Changes in XRD patterns showed a typical anatase type on the $TiO_2$/CNT composite prepared with a CNT matrix by the electroplating method in the TNB solution. In SEM micrographs, the titanium complex particles were uniformly distributed on the CNT surface. The results of chemical elemental analysis for the $TiO_2$/CNT composites showed that most of the spectra for these samples produced stronger peaks for carbon and Ti metal than those of any other element. Finally, the prominent photoelectrocatalytic (PEC) activities of the $TiO_2$/CNT composites could be attributed to the combined effects of photodegradation of $TiO_2$, electron assistance of CNT and the application of a sufficient voltage.

Photoelectrocatalytic Degradation of Dyes in Aqueous Solution Using CNT/TiO₂ Electrode

Zhang, Feng-Jun,Liu, Jin,Chen, Ming-Liang,Oh, Won-Chun 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3

The effect of photoelectrocatalytic (PEC) degradation for different dyes with the CNT/$TiO_2$ electrode was studied. The prepared electrode was characterized with surface properties, structural crystallinity, elemental identification, and PEC activity. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine CNT. This indicated the blocking of micropores on the surface of CNT, which was further supported by observation via FESEM. XRD patterns of the composites showed that the CNT/$TiO_2$ composite contained a mixing anatase and rutile phase. EDX spectra showed the presence of C, O and Ti peaks for all samples. The decomposition efifciency of the prepared electrode was evaluated by the PEC degradation of three dyes (methylene blue (MB), rhodamine B (RH.B), methyl orange (MO)). The variations of the FT-IR spectra and pH value of dye solutions were measured during the PEC system; it was found that the CNT/$TiO_2$ electrode has better PEC degradation for MB solution than that of RH.B and MO. The proposed degradation mechanism was present.