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Sonochemical Synthesis and Sonocatalysis Performance Behavior of Ag2Se and Ag2Se/TiO2 Nanocomposites
Lei Zhu,오원춘 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.6
In this study, novel Ag2Se sensitized TiO2 nanocomposites were prepared by facile sonochemical assisted synthesis method. The as-prepared products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and N2 adsorption BET analysis. The as-prepared Ag2Se/TiO2 nanocomposites simultaneously possessed great adsorptivity for organic dyes and efficient charge separation properties. In the decolorization of rhodamine B, a significant enhancement in the reaction rate was observed for the Ag2Se/TiO2 nanocomposite compared to the cases of using pure P25 or TiO2. The sonocatalysis activity was higher due to the greater formation of reactive radicals, as well as to the increase of the active surface area of the Ag2Se/TiO2 nanocomposite.
ZHU LEI,조대헌,이소영 한국국토정보공사 2017 지적과 국토정보 Vol.47 No.2
Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS-DNB) data provides a much higher capability for observing and quantifying nighttime light (NTL) brightness in comparison with Defense Meteorological Satellite-Operational Linescan System (DMSP-OLS) data. In South Korea, there is little research on the detection of NTL brightness change using VIIRS-DNB data. This study analyzed the spatial distribution and change of NTL brightness between 2013 and 2016 using VIIRS-DNB data, and detected its spatial relation with possible influencing factors using regression models. The intra-year seasonality of NTL brightness in 2016 was also studied by analyzing the deviation and change clusters, as well as the influencing factors. Results are as follows: 1) The higher value of NTL brightness in 2013 and 2016 is concentrated in Seoul and its surrounding cities, which positively correlated with population density and residential areas, economic land use, and other factors; 2) There is a decreasing trend of NTL brightness from 2013 to 2016, which is obvious in Seoul, with the change of population density and area of industrial buildings as the main influencing factors; 3) Areas in Seoul, and some surrounding areas have high deviation of the intra-year NTL brightness, and 71% of the total areas have their highest NTL brightness in January, February, October, November and December; and 4) Change of NTL brightness between summer and winter demonstrated a significantly positive relation with snow cover area change, and a slightly and significantly negative relation with albedo change.
Analysis on the Operation of a Charging Station with Battery Energy Storage System
Zhu, Lei,Pu, Yongjian The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
Fossil oil, as the main energy of transportation, is destined to be exhausted. The electrification of transportation is a sustainable solution to the energy crisis, since electric power could be acquired from the inexhaustible sun, wind and water. Among all the problems that hinder the development of Electric Vehicle (EV) industry, charging issue might be the most prominent one. In this paper, the service process of a charging station with Battery Energy Storage System (BESS) is analyzed by means of $Cram{\acute{e}}r$ - Lundberg model which has been intensively utilized in ruin theory. The service quality is proposed in two dimensions: the service efficiency and the service reliability. The arrival rate and State of Charge (SOC) upon arrival are derived from 2009 National Household Travel Survey (NHTS). The simulations are performed to show how the service quality is determined by the system parameters such as the number of servers, the service rate, the initial capacity, the charge rate and the maximum waiting time. At last, the economic analysis of the system is conducted and the best combination of the system parameters are given.
Lei Yang,Shuai Guo,Qiuling Yang,Yuankun Zhu,Bing Dai,Hailing Yu,Pei Lei,Jiecai Han,Ying Hou,Jiaqi Zhu 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.6
The preferentially oriented In2O3 thin films were prepared on glass substrates by conventional magnetron sputtering with Ar+ plasma exposure at room temperature. Based on the x-ray diffraction, x-ray photoelectron spectroscopy, and UV photoelectron spectroscopy results, it was found that the Ar+ plasma exposure not only enhanced the low-temperature crystallization of In2O3 thin films, but also led to a dramatic improvement in the work function. Furthermore, it demonstrated that the shift mechanism of the work function in In2O3 thin films mainly combined with theelimination of oxygen defects and the change of the preferential orientation of In2O3 film surface.
Lei Zhu,조순복,Shu Ye,Kefayat Ullah,오원춘 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.3
This paper introduces a microwave-assisted synthesis method to prepare hybrid Bi2Se3-GR/TiO2 nanocomposites, which exhibitsuperior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbancespectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with Bi2Se3 and TiO2nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observedwith Bi2Se3-GR/TiO2 composites. The degradation rate(kapp) obtained for sonophotocatalysis was 6.8× 10-3 min-1, roughly 2.2 timesbetter than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greaterformation of reactive radicals as well as an increase of the active surface area of the Bi2Se3-GR/TiO2 composites. The high activityis attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of Bi2Se3-GR/TiO2.
Lei Zhu,조순복,조정환,Shu Ye,Kefayat Ullah,오원춘 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.3
Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparationof MnS-ACF/TiO2 composites with titanium (IV) n-butoxide (TNB). The properties of MnS-ACF/TiO2 composites were characterizedby XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elementsMn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. Theresults demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently,the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by TiO2. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.
Zhu, Lei,Jo, Sun-Bok,Jo, Jung-Hwan,Ye, Shu,Ullah, Kefayat,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.3
Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparation of MnS-$ACF/TiO_2$ composites with titanium (IV) n-butoxide (TNB). The properties of MnS-$ACF/TiO_2$ composites were characterized by XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elements Mn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. The results demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently, the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by $TiO_2$. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.
Zhu, Lei,Oh, Won-Chun The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.3
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.
Zhu, Lei,Jo, Sun-Bok,Ye, Shu,Ullah, Kefayat,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.3
This paper introduces a microwave-assisted synthesis method to prepare hybrid $Bi_2Se_3-GR/TiO_2$ nanocomposites, which exhibit superior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbance spectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with $Bi_2Se_3$ and $TiO_2$ nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observed with $Bi_2Se_3-GR/TiO_2$ composites. The degradation rate($k_{app}$) obtained for sonophotocatalysis was $6.8{\times}10^{-3}min^{-1}$, roughly 2.2 times better than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greater formation of reactive radicals as well as an increase of the active surface area of the $Bi_2Se_3-GR/TiO_2$ composites. The high activity is attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of $Bi_2Se_3-GR/TiO_2$.
Zhu, Lei,Ye, Shu,Asghar, Ali,Bang, Seong-Ho,Oh, Won-Chun The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.1
In this study, the fabrication of zeolite combined activated carbon spherical samples was carried out as follows. Briefly, ZSM-5 zeolite and activated carbon were composed as main absorbent materials; by controlling the weight percentage of zeolite and binder materials, a series of spherical samples (AZP 4, 6, 8) were prepared. These spherical samples were characterized by BET, XRD, SEM, EDX, and pressure drop; benzene and iodine adsorption tests, bactericidal effect test, and ignition temperature test were also performed. The adsorption capability was found to depend on the BET surface area; the spherical samples AZP6 with high BET surface area of $1011m^2/g$ not only exhibited excellent removal effects for benzene (24.9%) and iodine (920mg/g) but also a good bactericidal effect. The enhanced ignition temperature may be attributed to the homogeneous dispersion conditions and the proper weight percentage ratio between zeolite and activated carbon.