• Title, Summary, Keyword: DPCO

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Synthesis and Characterization of ZnS and ZnS/TiO2 Nanocomposites and Their Enhanced Photo-decolorization of MB and 1,5-Diphenyl Carbazide

  • Meng, Ze-Da;Ullah, Kefayat;Zhu, Lei;Ye, Shu;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.51 no.4
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    • pp.307-311
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    • 2014
  • ZnS and $ZnS/TiO_2$ were prepared by chemical deposition. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). The generation of reactive oxygen species was detected by monitoring the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Excellent catalytic degradation of methylene blue (MB) solution was observed using the $ZnS/TiO_2$ composites during irradiation with visible light. The results show that the photocatalytic performance of $TiO_2$ nanoparticles is improved by loading with ZnS.

Detection of Oxygen Species Generated from Ag2Se-Graphene Heterojunction Photocatalysts with Excellent Visible Light Driven Photocatalytic Performance

  • Meng, Ze-Da;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.27 no.5
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    • pp.255-262
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    • 2017
  • Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substances in natural water environments and can completely destroy various organic pollutants in waste water. In this study, we used graphene oxide modified $Ag_2Se$ nanoparticles to enhance photochemically generated oxygen (PGO) species activity. Surface area and pore volumes of the $Ag_2Se-graphene$ ($Ag_2Se-G$) samples showed catastrophic decrease due to deposition of $Ag_2Se$. The generation of reactive oxygen species was detected through the oxidation reaction of DPCI to DPCO. The photocurrent density and the PGO effect increase in the case of the use of modified graphene. The PGO effect of the graphene modified with $Ag_2Se$ composites increased significantly due to a synergetic effect between graphene and the $Ag_2Se$ nanoparticles. The photocatalytic activity of sample was evaluated by measuring the degradation of organic pollutants such as methylene blue (MB) and industrial dyes such as Texbrite BA-L (TBA) under visible light.

Novel Bi2S3/TiO2 Heterogeneous Catalyst: Photocatalytic Mechanism for Decolorization of Texbrite Dye and Evaluation of Oxygen Species

  • Zhu, Lei;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.53 no.1
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    • pp.56-62
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    • 2016
  • A heterogeneous $Bi_2S_3/TiO_2$ composite catalyst was synthesized via a green ultrasonic-assisted method and characterized by XRD, SEM, EDX, TEM analysis. The results clearly show that the $TiO_2$ particles were homogenously coated with $Bi_2S_3$ particles, indicating that $Bi_2S_3$ particle agglomeration was effectively inhibited after the introduction of anatase $TiO_2$. The Texbrite BA-L (TBA) degradation rate constant for $Bi_2S_3/TiO_2$ composites reached $8.27{\times}10^{-3}min^{-1}$ under visible light, much higher than the corresponding value of $1.04{\times}10^{-3}min^{-1}$ for $TiO_2$. The quantities of generated hydroxyl radicals can be analyzed by DPCI degradation, which shows that under visible light irradiation, more electron-hole pairs can be generated. Finally, the possible mechanism for the generation of reactive oxygen species under visible-light irradiation was proposed as well. Our result shows the significant potential of $Bi_2S_3$-semiconductor-based $TiO_2$ hybrid materials as catalysts under visible light for the degradation of industry dye effluent substances.

Synthesis of Nanosized SnS-TiO2 Photocatalysts with Excellent Degradation Effect of TBA under Visible Light Irradiation

  • Meng, Ze-Da;Zhu, Lei;Ullah, Kefayat;Ye, Shu;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.25 no.9
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    • pp.455-461
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    • 2015
  • SnS-$TiO_2$ nanocomposites are synthesized using simple, cheap, and less toxic $SnCl_2$ as the tin (II) precursor. The prepared nanoparticles are characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectra (DRS). The XRD and TEM results indicate that the prepared product has SnS nanoparticles and a grain diameter of 30 nm. The DRS demonstrate that SnS-$TiO_2$ possesses the absorption profile across the entire visible light region. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and photocatalytic effect increase with the modified SnS. Excellent catalytic degradation of Texbrite BA-L (TBA) solution is observed using the SnS-$TiO_2$ composites under visible light irradiation. It is proposed that both the strong visible light absorption and the multiple exciton excitations contribute to the high visible light photocatalytic activity.