Jong-Geun Choi

Synthesis of fullerene modified with Ag2S with high photocatalytic activity under visible light

We improve the photocatalytic effect of Ag2S under visible light by using fullerene modified with Ag2S nanoparticles. Surface areas and pore volumes of the Ag2S–fullerene samples showed catastrophic decreases due to the deposition of Ag2S. The generation of reactive oxygen species was 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 the photocatalytic effect increase in the case with the modified fullerene. In comparison with the separate effects of Ag2S and fullerene nanoparticles, the photocatalytic effect of the fullerene modified with Ag2S composites is increased significantly due to the synergetic effect between the fullerene and the Ag2S nanoparticles.

Effect of Pt treated fullerene/TiO2 on the photocatalytic degradation of MO under visible light

Platinum treated fullerene/TiO2 composites (Pt-fullerene/TiO2) were prepared using a sol–gel method. The composite obtained was characterized by FT-IR, BET surface area measurements, X-ray diffraction, energy dispersive X-ray analysis, transmission electron microscopy (TEM) and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the Pt-TiO2, fullerene-TiO2 and Pt-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed and Pt-fullerene/TiO2 has the best photocatalytic activity, which may be attributable to increase of the photo-absorption effect by the fullerene and the cooperative effect of the Pt.

Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light

WO3-treated fullerene/TiO2 composites (WO3-fullerene/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the WO3-fullerene, fullerene-TiO2, and WO3-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed, and WO3-fullerene/TiO2 has the best photocatalytic activity; it may attribute to the increase of the photo-absorption effect by the fullerene and the cooperative effect of the WO3.

Sonocatalytic degradation of Rhodamine B in the presence of C60 and CdS coupled TiO2 particles.

CdS-TiO2 and CdS-C60/TiO2 were prepared using C60, cadmium acetate dehydrate [(CH3COO)2Cd·2H2O], sodium sulfide (Na2S·5H2O) and titanium (IV) n-butoxide by a sol-gel method. The prepared sonocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM). A rhodamine B (RhB) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an RhB solution was observed using the CdS-C60/TiO2 composites under ultrasonic irradiation. C60 coupled CdS-TiO2 can enhance the Brunauer-Emmett-Teller (BET) surface area and increase the decolorization rate for rhodamine B solution. The results also shows that increase the content of CdS can enhance the catalytic activity.

Synthesis and Characterization of Metal (Pt, Pd and Fe)-graphene Composites

In this study, we prepared graphene by using the modified Hummers-Offeman method and then introduced the metals (Pt, Pd and Fe) for dispersion on the surface of the graphene for synthesis of metal-graphene composites. The characterization of the prepared graphene and metal-graphene composites was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM). According to the results, it can be observed that the prepared graphene consists of thin stacked flakes of shapes having a well-defined multilayered structure at the edge. And the metal particles are dispersed uniformly on the surface of the graphene with an average particle size of 20 ㎚.

Preparation of ZnS-Graphene/TiO2 Composites Designed for Their High Photonic Effect and Photocatalytic Activity Under Visible Light

In this study, ZnS combined graphene/TiO2 (ZGT) composites were prepared by a sol–gel method to improve the photocatalytic performance of TiO2. These composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible light irradiation. The photodegradation rate of MB under visible light irradiation reached 90.1% after 150 minutes. The kinetics of MB degradation was plotted alongside the values calculated from the Langmuir–Hinshelwood equation. The 0.2 ZnS-graphene/TiO2 sample showed the best photocatalytic activity, which was attributed to cooperative reaction due to an increase of the photo-absorption effect by graphene and the photocatalytic effect by ZnS.

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.

Synthesis of carbon nanomaterials-CdSe composites and their photocatalytic activity for degradation of methylene blue

We use multi-walled carbon nanotube (MWCNT) and graphene as carbon nanomaterials to obtain carbon nanomaterilas-CdSe composites using a facile hydrothermal method. The intrinsic characteristics of resulting composites were studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometer. The as-prepared carbon nanomaterilas-CdSe composites possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously. Hence, in the photodegradation of methylene blue, a significant enhancement in the reaction rate was observed with carbon nanomaterilas-CdSe composites, compared to the CdSe compound.

Photoelectrocatalytic Degradation of Methylene Blue Over M-CNT/TiO2 (M=Y, Ag, and Pt) Composite Electrodes

In this study, carbon nanotubes modified with different metal ions (M=Y, Ag and Pt) were employed for the fabrication of M-CNT/TiO2 electrodes. The fabricated electrodes were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray and photoelectrocatalytic activity. It was found that the photoelectrocatalytic degradation efficiencies of methylene blue solution over M-CNT/TiO2 electrodes were better than that of nonmetal ion-treated CNT/TiO2 electrodes. In comparison of the three M-CNT/TiO2 composites, the photoelectrocatalytic degradation efficiency (76%) of Ag-CNT/TiO2 for MB solution was the best results under visible light.

Rare Earth Oxide-Treated Fullerene and Titania Composites with Enhanced Photocatalytic Activity for the Degradation of Methylene Blue

Rare earth oxide-treated fullerene and titania composites (Y-fullerene/TiO2) were prepared by the sol-gel method. The products had interesting surface compositions. X-ray diffraction patterns of the composites showed that the Y-fullerene/TiO2 composites contained a single and clear anatase phase. The surface properties were observed by scanning electron microscopy, which gave a characterization of the texture on the Y-fullerene/TiO2 composites and showed a homogenous distribution of titanium particles. The energy-dispersive X-ray spectra showed the presence of C and Ti with strong Y peaks. The composite obtained was also characterized with transmission electron microscopy and UV-Vis spectroscopy. The photocatalytic results showed that the Y-fullerene/TiO2 composites had excellent activity for the degradation of methylene blue under visible light irradiation. This was attributed to both the effects on the photocatalysis of the supported TiO2 by charge transfer by the fullerene, and the introduction of yttrium to enhance photo-generated electron transfer.