• 한국세라믹학회지
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• 제52권3호
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• pp.173-179
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• 2015

We report the facile synthesis of graphene-$CdLa_2S_4$ composite through a facile solvothermal method at low temperature. The as-prepared products were characterized by X-ray diffraction (XRD) and by Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and BET analysis, revealing the uniform covering of the graphene nanosheet with $CdLa_2S_4$ nanocrystals. The as-prepared samples show a higher efficiency for the photocatalytic degradation of typical MB dye compared with P25 and $CdLa_2S_4$ bulk nanoparticles. The enhancement of visible-light-responsive photocatalytic properties by decolorization of Rh.B dye may be attributed to the following causes. Firstly, graphene nanosheet is capable of accepting, transporting and storing electrons, and thus retarding or hindering the recombination of the electrons with the holes remaining on the excited $CdLa_2S_4$ nanoparticles. Secondly, graphene nanosheet can increase the adsorption of pollutants. The final cause is that their extended light absorption range. This work not only offers a simple way to synthesize graphene-based composites via a one-step process at low temperature but also a path to obtain efficient functional materials for environmental purification and other applications.

• 한국세라믹학회지
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• 제50권6호
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• pp.504-509
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• 2013

In this study, ZnSe-$TiO_2$ composites were synthesized by a facile hydrothermal-assisted sol-gel process and characterized by nitrogen adsorption isotherms (77 K), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometry. The photocatalytic activity was investigated by decoloration methylene blue (MB), methyl orange (MO), and rhodamine B (Rh.B) in an aqueous solution under visible light irradiation. The results revealed that the photocatalytic activity of the ZnSe-$TiO_2$ photocatalyst was much higher than that of pure$TiO_2$. The ZnSe nanoparticles, which act as a photosensitizer, not only extend the spectral response of $TiO_2$ to the visible region but also reduce charge recombinations.

• 한국환경과학회지
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• 제19권5호
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• pp.577-584
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• 2010

The generation of $TiO_2$ nanoparticles by a thermal decomposition of titanium tetraisopropoxide (TTIP) was carried out experimentally using a tubular electric furnace at various synthesis temperatures (700, 900, 1100 and $1300^{\circ}C$) and precursor heating temperatures (80, 95 and $110^{\circ}C$). Effects of degree of crystallinity, surface area and anatase mass fraction of those $TiO_2$ nanoparticles on photocatalytic properties such as decomposition of methylene blue was investigated. Results show that the primary particle diameter obtained from thermal decomposition of TTIP was considerably smaller than the commercial photocatalyst (Degussa, P25). Also, those specific surface areas were more than 134.4 $m^2$/g. Resultant $TiO_2$ nanoparticles showed improved photocatalytic activity compared with Deggusa P25. This is contributed to the higher degree of crystallinity, surface area and anatase mass fraction of $TiO_2$ nanoparticles compared with P25.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.98-102
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• 2021

GaOOH is obtained via hydrothermal synthesis procedure. The formed GaOOH is turned into α-Ga₂O₃ at 500℃ annealing. As the annealing temperatures increase the α-Ga₂O₃ is in part turned into β-Ga₂O₃ and fully turned into β-Ga₂O₃ after 1100℃. XPS and PL results reveal that heterojunction interface between α-Ga₂O₃ and β-Ga₂O₃ become maxim at 500℃ annealing condition, which result in the highest photocatalytic activity. The presence of heterojunction interface slows down the recombination process by separating photogenerated electron-hole pairs and thereby enhance the overall photocatalytic activity.

• Advances in nano research
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• 제12권4호
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• pp.415-426
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• 2022

Nickel substituted cobalt-zinc ferrite nanoparticles with composition Co_0.5Zn_0.5Ni_xFe_2-xO₄ (x = 0.25, 0.5, 0.75, 1.0) were synthesized using a wet chemical method named citrate precursor method. Various characterizations of the prepared nanoferrites were done using X-ray powder diffractometry (XRD), Scanning electron microscopy (SEM), UV visible spectroscopy and Fourier transform spectroscopy technique (FT-IR). XRD confirmed the formation of cubic spinel structure of the samples with single phase having one characteristic peak at (311). The value of optical band gap (E_g) was found to decrease with Ni substitution and have values in the range 2.30eV to 1.69eV. A Fenton-type system was created by photocatalytic activity using source of visible light for removal of methylene blue dye. Observations revealed increase in the degradation of methylene blue dye with increasing nickel content in the samples. The degradation percentage was increased from 77.32% for x = 0.25 to 90.16% for x = 1.0 in one hour under the irradiation of visible light. Also, the degradation process was found to have pseudo first order kinetics model. Hence, it can be observed that synthesized nickel doped cobalt-zinc ferrites have good capability for water purification and its degradation efficiency enhanced with increase in nickel concentration.

• 한국분말재료학회지
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• 제25권3호
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• pp.226-231
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• 2018

F-containing $TiO_2$ nanopowders are synthesized using simple wet processes (precipitation-based and hydrothermal) from ammonium hexafluorotitanate (AHFT, $(NH_4)_2TiF_6$) as a precursor to apply as a photocatalyst for the degradation of rhodamine B (RhB). The surface properties of the prepared samples are evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results confirm that the synthesized anatase $TiO_2$ has sphere-like shapes, with numerous small nanoparticles containing fluorine on the surface. The photocatalytic activity of F-containing $TiO_2$ compared with F-free $TiO_2$ is characterized by measuring the degradation of RhB using a xenon lamp. The photocatalytic degradation of F-containing $TiO_2$ exhibits improved photocatalytic activity, based on the positive effects of adsorbed F ions on the surface.

• 한국재료학회지
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• 제11권7호
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• pp.537-544
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• 2001

$TiO_2$광촉매릉 반응성 스퍼터링법을 이웅하여 박막으로 제조하고 유기물 및 살균실험을 통하여 미세조직이 광촉매 효율에 미치는 영향을 조사하고자 하였다. 광촉매 효율측정을 위하여 페놀분해실험 및 E.coli 078을 이용한 살균실험을 행하였다. $TiO_2$박막에 의한 페놀분해실험 시, 전자수용체인 산소의 공급에 의하여 분해효율이 2배까지 증가하였다. E.coli 078분해실험의 경우, 광촉매 $TiO_2$박막을 사웅하여 살균하였을때 UV만 조사하여 살균하였을 경우 보다 분해효율이 최고 70% 이상 증가하였다. 페놀분해실험과 E.coli 078 살균실험 결과 저결정성 박막의 경우 분해능이 매우 미약하였으며, 표면조도가 높고 결정성이 우수한 박막의 경우에 높은 광촉매 효율을 나타내어$TiO_2$박막의 광촉매 효과는 표면형상과 결정성이 매우 중요한 인자로 작용하였다.

• 한국세라믹학회지
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• 제49권2호
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• pp.135-141
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• 2012

To improve the visible-light induced photocatalytic application performances of $TiO_2$, in this study, the $NiS_2$ modied $TiO_2$ composites were prepared by two methods: hydrothermal method and sol-gel method. The composites were denoted as hs-$NiS_2$/$TiO_2$, and sg-$NiS_2$/$TiO_2$ and characterized by XRD, UV-vis absorbance spectra, SEM, TEM, EDX, and BET analysis. The photocatalytic activities under visible light were investigated by the degradation of methyl orange (MO). The photodegradation rate of methyl orange under visible light with $NiS_2$/$TiO_2$ composites was markedly higher than that of pure $TiO_2$, and the effect of hs-$NiS_2$/$TiO_2$ composites was better than that of sg-$NiS_2$/$TiO_2$. The results indicate that the hydrothermal process could partly inhibit the agglomeration of $NiS_2$/$TiO_2$. Thus, the dispersion of nanoparticles was improved, and that the promoting effect of $NiS_2$ could extend the light absorption spectrum toward the visible region.

• 멤브레인
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• 제29권6호
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• pp.299-307
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• 2019

광촉매는 물에서 유기 염료를 분해하는 친환경적 기술이다. 산화 텅스텐은 이산화 티타늄에 비해 더 작은 밴드갭을 지니고 있어 광촉매 나노물질로서 활발히 연구되고 있다. 계층적 구조의 합성, 백금 도핑, 나노 복합물 또는 다른 반도체와의 결합 등이 광촉매 분해 효율을 향상시키는 방법들로 연구되고 있다. 이들 방법들은 광 파장의 적색편이를 유도하여 전자 이동, 전자-정공 쌍의 형성과 재결합에 영향을 미친다. 산화 텅스텐의 형태 개질을 통해 앞서 언급한 광촉매 분해 효율을 향상시키는 방법들과 합성에 대해 분석하였으며 금속 산화물과 탄소 복합재를 결합하는 방법이 새로운 물질의 합성이 필요없으며 가장 효율적인 방법으로 조사되었다. 이러한 광촉매 기술은 수처리 분리막기술과 모듈화하여 정수처리 목적으로 사용될 수 있다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.264-265
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• 2014

This Paper reports the photocatalytic activity of $g-C_3N_4/NaTaO_3$ hybrid composite photocatalysts synthesized by ball-mill method. The $g-C_3N_4$ and $NaTaO_3$ were individually prepared by Solid state reaction and microwave hydrothermal process, respectively. The $g-C_3N_4/NaTaO_3$ composite showed the enhanced photocatalytic activity for degradation of rhodamine B dye (Rh. B) under simulated solar light irradiation. The results revealed that the band-gap energy absorption edge of hybrid composite samples was shifted to a longer wavelength as compared to $NaTaO_3$ and the 50 wt% $g-C_3N_4/NaTaO_3$ hybrid composite exhibited the highest percentage (99.6 %) of degradation of Rh. B and the highest reaction rate constant ($0.013min^{-1}$) in 4 h which could be attributed to the enhanced absorption of the hybrid composite photocatalyst in the UV-Vis region. Hence, these results suggest that the $g-C_3N_4/NaTaO_3$ hybrid composite exhibits enhanced photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation in comparison to the commercial $NaTaO_3$.