• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.133-139
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• 2010

Photoelectrocatalytic decolorization of methlene blue (MB) in the presence of two types of carbon nanotube/titania and yttrium-treated carbon nanotube/titania electrodes in aqueous solutions were studied under visible light. The prepared composite electrodes were characterized by X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray analysis, and photoelectrocatalytic activity. The photoelectrocatalytic performances of the supported catalysts were evaluated for the decolorization of MB solution under visible light irradiation. The results showed that yttrium incorporation enhanced the decolorization rate of MB. It was found that the photoelectrocatalytic degradation of a MB solution could be attributed to the combined effects caused by the photo-degradation of titania, the electron assistance of carbon nanotube network, the enhancement of yttrium and a function of the applied potential. The repeatability of photocatalytic activity was also tested. The presence of yttrium enhanced the hydrophillicity of yttrium-carbon nanotubes/titania electrode because more OH groups can be adsorbed on the surface.

• Environmental Engineering Research
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• 제14권1호
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• pp.32-40
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• 2009

In this study, we have prepared three kinds of carbon nanometer tube $CNT/TiO_{2}$ electrodes through impregnation with different concentration titanium n-butoxide (TNB) solution. The prepared electrodes were characterized with surface properties, structural crystallinity, elemental identification and photoelectrocatalytic 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 SEM. XRD results showed patterns for the composites and a typical single and clear anatase crystal structure. The main elements such as C, O and Ti were existed for all samples from the EDX data. The catalytic efficiency of the developed electrode was evaluated by the photoelectrodegradation of methylene blue (MB). The positive potential applied in photoelectrocatalytic (PEC) oxidation was studied. It was found that photoelectrocatalytic (PEC) decomposition of MB solution could be attributed to combination effects between $TiO_2$ photocatalytic and CNT electro-assisted. Through the comparison between photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation, it was found that the PEC oxidation efficiency for MB is higher than that of PC oxidation.

• 한국환경보건학회지
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• 제34권3호
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• pp.226-232
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• 2008

A feasibility study for the application of the photoelectrocatalytic decolorization of Rhodamine B (RhB) was performed in a photoelectrochemical reactor with immobilized $TiO_2$ particle. The effects of operating conditions, such as current, electrolyte and pH were evaluated. The experimental results showed that optimum $TiO_2$ dosage and current in the photoelectrocatalytic process were 83.3 g/l and 0.5 A, respectively. It was found that the RhB could be degraded more efficiently by this photoelectrocatalytic process than the sum of the two individual oxidation processes (photocatalytic and electrolytic process). The addition of NaCl increased the initial decolorization rate and reduced reaction time. The optimum dosage of NaCl was 0.15 g/l. The decolorization rate of the photoelectrocatalytic process increased sharply with a decrease in pH value. However when the NaCl was added, the pH effect was not high.

• 대한환경공학회지
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• 제30권8호
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• pp.823-830
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• 2008

Rhodamine B(RhB) 탈색에 대한 광전기촉매 공정의 적용가능성을 분말 TiO$_2$를 충전한 슬러리 광전기촉매 반응기에서 연구하였다. 광전기촉매 공정의 반응기 시스템은 분말 TiO$_2$, Pt 전극 및 3개의 8 W UV-C 등으로 구성되어 있다. 전류, 전해질, 공기 유량 및 전극 재질과 같은 운전 인자의 영향을 고찰하였다. 광전기촉매 공정의 최적 광촉매 량과 전류는 각각 0.4 g/L과 0.02A이었다. 광촉매 공정과 전기분해 단독 공정에 의해 분해되는 RhB의 합보다 광전기촉매 공정에 의해 더 빨리 분해되었는데, 광촉매 공정과 전기분해 공정의 결합에 의한 시너지 효과를 나타내는 것으로 사료되었다. 광전기촉매 공정은 공기 유량에 의해 영향을 받는 것으로 나타났고 최적 공기 유량은 2 L/min이었다. RhB 탈색에 대한 전극 재질과 NaCl 효과는 본 실험범위에서는 크지 않은 것으로 나타났다.

• 한국환경과학회지
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• 제17권9호
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• pp.1023-1032
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• 2008

The feasibility study of the application of the photoelectrocatalytic and electrolytic/UV decolorization of Rhodamine B (RhB) was investigated in the photoelectrocatalytic and electrolytic/UV process with $TiO_2$ photoelectrode and DSA (dimensionally stable anode) electrode. Three types of $TiO_2$ photoelectrode were used. Thermal oxidation electrode (Th-$TiO_2$) was made by oxidation of titanium metal sheet; sol-gel electrode (5G-$TiO_2$) and powder electrode (P-$TiO_2$) were made by coating and then heating a layer of titania sol-gel and slurry $TiO_2$ on titanium sheet. DSA electrodes were Ti and Ru/Ti electrode. The relative performance for RhB decolorization of each of the photoelecoodes and DSA electrodes is: Ru/Ti > Ti > SG-$TiO_2$ > Th-$TiO_2$. It was observed that photoelectrocatalytic decolorization of RhB is similar to the sum of the photocatalytic and electrolytic decolorization. Therefore the synergetic effect was not showed in pthotoelectrocatalytic reaction. $Na_{2}SO_{4}$ and NaCl showed different decolorization effect between pthotoelectrocatalytic and electrolytic/UV reaction. In the presence of the NaCl, RhB decolorization of Ru/Ti DSA electrode was higher than that of the other photoelectrode and Ti electrode. Optimum current, NaCl dosage and UV lamp power of the electrolytic/UV process (using Ru/Ti electrode) were 0.75 A, 0.5 g/L and 16 W, respectively.

• 한국재료학회지
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• 제18권11호
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• pp.583-591
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• 2008

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.

• 한국세라믹학회지
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• 제46권3호
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• pp.263-270
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• 2009

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.

• 한국세라믹학회지
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• 제46권6호
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• pp.554-560
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• 2009

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 Brunauer-Emmett-Teller (BET) surface areas of $TiO_2$/CNT composites decrease as the electrochemical operating time increases. Changes in XRD patterns show a typical anatase type on the $TiO_2$/CNT composite prepared with a CNT matrix by the electroplating method in a TNB solution. In SEM micrographs, the titanium complex particles are uniformly distributed on the CNT surface. The results of chemical elemental analysis for the $TiO_2$/CNT composites show that most of the spectra for these samples produce stronger peaks for carbon and Ti metal than for any other element. Finally, the prominent photoelectrocatalytic activities of the $TiO_2$/CNT composites can be attributed to the combined effects of photodegradation of $TiO_2$, electron assistance of CNT, and the application of a sufficient voltage.

• 한국세라믹학회지
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• 제46권4호
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• pp.357-364
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• 2009

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.

• 한국결정성장학회지
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• 제20권1호
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• pp.35-42
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• 2010

In this paper, three types of CNT/$TiO_2$ composite electrodes were prepared with different methods. The changes in XRD patterns showed that the Electrode A contained a mixed phase of anatase and rutile while the Electrode B and Electrode C contained a typical single and clear anatase crystal structure. From SEM micrographs, $TiO_2$ particles were adhered on the surface of the CNT network in the forms of small clusters. The results of chemical elemental analysis indicated that the main elements such as C, O and Ti were existed. The results demonstrated that the efficiency of photoelectrocatalytic (PEC) oxidation for methylene blue (MB) was higher than that of photocatalytic (PC) oxidation. There was a clear enhancement trend of the MB degradation using the prepared CNT/$TiO_2$ composite electrodes with an increase of applied potential. Finally, the prominent PEC activities of the CNT/$TiO_2$ composites could be attributed to combination effects of photo-degradation of $TiO_2$, electron assistant of CNT and function of applied potential.