• Clean Technology
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• v.23 no.1
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• pp.95-103
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• 2017

In this study, $ATiO_3$ (A = Ca, Sr, Ba) perovskite, which is the widely known for non $TiO_2$ photocatalysts, were synthesized using sol-gel method. And Ni was added at the A site of $ATiO_3$ by using that it is easy to incorporate. The physicochemical characteristics of the obtained $ATiO_3$ and Ni-$ATiO_3$ particles were confirmed using the X-ray diffraction (XRD) UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), the $N_2$ adsorption-desorption isotherm measurement, and X-ray photoelectron spectroscopy (XPS). The $H_2$ was produced using the photolysis of MeOH. Using the Ni-$ATiO_3$ photocatalysts, $H_2$ production was higher than using the $ATiO_3$ photocatalysts. Especially, $273.84mmolg^{-1}$ $H_2$ was produced after 24 h reaction over the Ni-$SrTiO_3$. Also in the water (0.1 M KOH) with the Ni-$SrTiO_3$, $H_2$ production was $961.51mmolg^{-1}$ after 24 h reaction.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.655-662
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• 2017

Sulfide photocatalysts, CdS and CdZnS, were synthesized using a simple precipitation method and their photocatalytic activities were evaluated by the degradation of rhodamine B under visible light irradiation. The effects of four inorganic salt additives, KCl, NaCl, $K_3PO_4$, and $Na_3PO_4$, on the photocatalytic reaction were examined and the role of $K^+$, $Na^+$, $Cl^-$ and $PO_4{^{3-}}$ ions during photocatalytic reaction was discussed. The added inorganic salts were shown to have a remarkable effect on the photocatalytic reaction. It was also found that the anions in inorganic salts have a much more profound effect on the reaction rate, as compared to the cations. Under the present experimental conditions, $PO_4{^{3-}}$ revealed a significant inhibitory effect on the degradation rate whereas $Cl^-$ enhanced the rate slightly. This work pointed out that the consideration of additive effects is needed in the photocatalytic reaction for wastewater treatment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.3.1-3.1
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• 2010

Water splitting reaction using photocatalysts is of great interest in the utilization of solar energy [1]. In the present work, visible light-responsive $TiO_2$ thin films (Vis-$TiO_2$) were prepared by a radio frequency magnetron sputtering (RF-MS) deposition method and applied for the separate evolution of $H_2$ and $O_2$ from water as well as the photofuel cell. Special attentions will be focused on the effect of HF treatment of Vis-$TiO_2$ thin films on their photocatalytic activities. Vis-$TiO_2$ thin films were prepared by an RF-MS method using a calcined $TiO_2$ plate and Ar as the sputtering gas. The Vis-$TiO_2$ thin films were then deposited on the Ti foil substrate with the substrate temperature at 873 K (Vis-$TiO_2$/Ti). Vis-$TiO_2$/Ti thin films were immersed in a 0.045 vol% HF solution at room temperature. The effect of HF treatments on the activity of Vis-$TiO_2$/Ti thin films for the photocatalytic water splitting reaction have been investigated. Vis-$TiO_2$/Ti thin films treated with HF solution (HF-Vis-$TiO_2$/Ti) exhibited remarkable enhancement in the photocatalytic activity for $H_2$ evolution from a methanol aqueous solution as well as in the photoelectrochemical performance under visible light irradiation as compared with the untreated Vis-$TiO_2$/Ti thin films. Moreover, Pt-loaded HF-Vis-$TiO_2$/Ti thin films act as efficient and stable photocatalysts for the separate evolution of $H_2$ and $O_2$ from water under visible light irradiation in the presence of chemical bias. Thus, HF treatment was found to be an effective way to improve the photocatalytic activity of Vis-$TiO_2$/Ti thin films. Furthermore, unique separate type photofuel cell was fabricated using a Vis-$TiO_2$ thin film as an electrode, which can generate electrical power under solar light irradiation by using various kinds of biomass derivatives as fuel. It was found that the introduction of an iodine ($I^-/{I_3}^-$) redox solution at the cathode side enables the development of a highly efficient photofuel cell which can utilize a cost-efficient carbon electrode as an alternative to the Pt cathode.

• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.124-129
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• 2003

The objectives of this study are to manufacture an efficient $TiO_2$, photocatalyst and to delineate optimum operational parameters for TCE (trichloroethylene) degradation in a photocatalytic oxidative reactor. The $TiO_2$ photocatalyst irradiated by 365 nm UV light is expected to increase degradation of TCE in solution by a series of photocatalytic oxidations in the reactor. A new membrane $TiO_2$ photocatalyst wns eventually developed by coating a mixture of Davan-C(0.24 wt%) and PVA(0.16 wt%) on the surface of slips using the slip-casting method. Results show that increase in the number of coating of $TiO_2$ sol on surface of photocatalysts and in the surface thickness improved the endurance and photocatalysts, but these physical modifications caused significant decrease in the overall degradation efficiency of TCE. Pre-aeration or recirculation of the influents to the reactors containing TCE increased degradation efficiency of TCE. The optimum operational conditions far the surface area of photocatalysts and UV light intensity appeared to be $1.47\;mL/cm^2$ and $225\;W/cm^2{\times}100$, respectively, in the reactor. Based on the overall experimental results, the photocatalytic oxidation of TCE with the new membrane $TiO_2$ photocatalyst is found to be very effective under the operational conditions delineated in this study.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.581-588
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• 2007

To enhance the photodecomposition of concentrated ammonia into N2, Pt/V-TiO2 photocatalysts were prepared using solvothermal and impregnation methods. Nanometer-sized particles of 0.1, 0.5 and 1.0 mol% V-TiO2 were prepared solvothermally, and then impregnated with 1.0 wt% Pt. The X-ray diffraction (XRD) peaks assigned to V2O5 at 30.20 (010) and Pt metal at 39.80 (111) and 46.20 (200) were seen in the 1.0 wt% Pt/ 10.0 mol% V-TiO2. The particle size increased in the order: pure TiO2, V-TiO2 and Pt/V-TiO2 after thermal treatment at 500 °C, while their surface areas were in the reverse order. On X-ray photoelectron spectroscopy (XPS), the bands assigned to the Ti2p3/2 and Ti2p1/2 of Ti4+-O were seen in all the photocatalysts, and the binding energies increased in the order: TiO2 < Pt/V-TiO2 < V-TiO2. The XPS bands assigned to the V2p3/2 (517.85, 519.35, and 520.55 eV) and V2p1/2 (524.90 eV) in the V3+, V4+ and V5+ oxides appeared over V-TiO2, respectively, while the band shifted to a lower binding energy with Pt impregnation. The Pt components of Pt/ V-TiO2 were identified at 71.60, 73.80, 75.00 and 76.90 eV, which were assigned to metallic Pt 4f7/2, PtO 4f7/2, PtO2 4f7/2, and PtO 4f5/2, respectively. The UV-visible absorption band shifted closer towards the visible region of the spectrum in V-TiO2 than in pure TiO2 and; surprisingly, the Pt/V-TiO2 absorbed at all wavelengths from 200 to 800 nm. The addition of vanadium generated a new acid site in the framework of TiO2, and the medium acidic site increased with Pt impregnation. The NH3 decomposition increased with the amount of vanadium compared to pure TiO2, and was enhanced with Pt impregnation. NH3 decomposition of 100% was attained over 1.0 wt% Pt/1.0 mol% V-TiO2 after 80 min under illumination with 365 nm light, although about 10% of the ammonia was converted into undesirable NO2 and NO. Various intermediates, such as NO2, -NH2, -NH and NO, were also identified in the Fourier transform infrared (FT-IR) spectra. From the gas chromatography (GC), FT-IR and GC/mass spectroscopy (GC/MS) analyses, partially oxidized NO and NO2 were found to predominate over V-TiO2 and pure TiO2, respectively, while both molecules were reduced over Pt/V-TiO2.

• Clean Technology
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• v.18 no.4
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• pp.419-425
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• 2012

This work explored the characteristics and the photocatalytic activities of S element-doped $TiO_2$ (S-$TiO_2$) and N element-doped $TiO_2$ (N-$TiO_2$) for the decomposition of gas-phase isopropyl alcohol (IPA) at sub-ppm concentrations, using a plug-flow reactor irradiated by 8-W daylight lamp or visible light-emitting-diodes (LEDs). In addition, the generation yield of acetone during photocatalytic processes for IPA at sub-ppm levels was examined. The surface characteristics of prepared S- and N-$TiO_2$ photocatalysts were analyzed to indicate that they could be effectively activated by visible-light irradiation. Regarding both types of photocatalysts, the cleaning efficiency of IPA increased as the air flow rate (AFR) was decreased. The average cleaning efficiency determined via the S-$TiO_2$ system for the AFR of 2.0 L $min^{-1}$ was 39%, whereas it was close to 100% for the AFR of 0.1 L $min^{-1}$. Regarding the N-$TiO_2$ system, the average cleaning efficiency for the AFR of 2.0 L $min^{-1}$ was above 90%, whereas it was still close to 100% for the AFR of 0.1 L $min^{-1}$. In contrast to the cleaning efficiencies of IPA, both types of photocatalysts revealed a decreasing trend in the generation yields of acetone with decreasing the AFR. Consequently, the N-$TiO_2$ system was preferred for cleaning of sub-ppm IPA to S-$TiO_2$ system and should be operated under low AFR conditions to minimize the acetone generation. In addition, 8-W daylight lamp exhibited higher cleaning efficiency of IPA than for visible LEDs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1204-1210
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• 2014

New control methods are proposed for indoor air quality by removing fine airborne dust-particles. As suspended fine dust-particles contain inorganic dust as well as fine organic bacteria, studies for simultaneous control of these contaminants are required. In this study, photocatalytic disinfection of indoor suspended microorganisms such as E. coli and Bacillus subtilis is performed by three types of photocatalysts with UVA irradiation. The UVA irradiation strength was controlled to the minimum $3{\mu}W/cm^2$, and ZnO, $TiO_2$, and ZnO/Laponite ball were used as the catalysts. The results indicate that E. coli was removed over 80 % after about 2 hours of reaction with UVA and all three types of photocatalysts, whereas only with UVA, around 50 % E. coli removal was obtained. Among the catalysts, ZnO/Laponite composite ball was found to have similar sterilizing capacity to $TiO_2$. However, in case of B. subtilis, which has thick cell wall in its spore state, disinfection was not effective under the low UVA irradiation condition, even with the catalysts. Further studies need to figure out the optimal UVA irradiation ranges as well as photocatalysts doses to control airborne dust, to provide healthy clean air environment.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.233-240
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• 1999

Industrial waste which highly loaded by halogenide phenols was photooxidized by laboratory-scale photooxidation of these organic impurities in the presence of aerotropic and titaniumdioxide as photocatalyst. The disapperance of organic compounds was determined as a function of the irradiation time. Some contaminants such as 2-chlorophenol, 2-bromphenol, 3-bromphenol, 4-bromphenol, 2,4-dibromophenol and 2,6-dibromophenol were photodegraded separately to obtain information on the reaction rates, reactivities, and reaction mechanisms of the photooxidation, and on the stoichiometric correlation between organic reactant and inorganic products concentration in the course of the photocatalytic photoreaction.

• Journal of the Korean Chemical Society
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• v.65 no.6
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• pp.415-418
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• 2021

• Carbon letters
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• v.22
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• pp.48-59
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• 2017

This study synthesized pure anatase carbon doped $TiO_2$ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/$TiCl_4$. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported $TiO_2$ nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the $TiO_2$ layer, and the XPS data suggested the substitution of titanium in $TiO_2$ by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported $TiO_2$ nanocrystals prepared by pyrolysis at 300, 350, and $400^{\circ}C$ for 3 h on a stainless steel mesh were actual supported carbon doped $TiO_2$ nanocrystals. Thus, $PAN/DMF/TiCl_4$ offers a facile, robust sol-gel related route for preparing supported carbon doped $TiO_2$ nanocomposites.