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Gyoung Hee Hong,Zhengyang Li,박진서,Zhenghua Li,Ki Yeong Kim,Chengbin Li,이정호,Mingshi Jin,Galen D. Stucky,Ji Man Kim 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-
Highly ordered mesoporous molybdenum dioxide (meso-MoO2) was successfully synthesized by a nanoreplicationmethod using a mesoporous silica template with 3D cubic Ia3d mesostructure. Structuralanalyses using X-ray diffraction, N2 sorption, and electron microscopy indicated that the meso-MoO2material exhibited high surface area (106 m2/g), large pore volume (0.66 cm3/g), and well-defined mesopores. Under the optimized reaction conditions, the meso-MoO2 catalyst showed excellent catalytic performancesfor the acetalization of glycerol with acetone (95.8% of glycerol conversion, and 97.8% ofsolketal selectivity) at 20 C, due to its high surface area with large number of acid sites. During recycling,the meso-MoO2 catalyst exhibited a slight decrease in activity; and after a simple regeneration at 350 C,the catalytic performances could be completely recovered. More importantly, a partial hydrophobic treatmentof the meso-MoO2 catalyst dramatically enhanced the water-tolerance during the catalytic reaction.
Zhengyang Kang,Yonghong Fu,Yun Chen,Jinghu Ji,Hao Fu,Shulin Wang,Rui Li 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.5 No.5
Tool-chip adhesion impacts on cutting performance significantly, especially in finish cutting process. To promote cutting tools’ anti-adhesion property, the concave micro-grooves texture (MGT) and convex volcano-like texture (VLT) were fabricated separately on lathe tools’ rake faces by laser surface texturing (LST). Various orientations of MGT and different area densities (9% and 48%) and regions (partial and full) of VLT were considered in textured patterns designing. The following orthogonal cutting experiments, machining of aluminum alloy 5038, analyzed tools’ performances including cutting force, cutting stability, chip shape, rake face adhesion and abrasion. It indicated that under dry finish cutting conditions, MGT contributed to cutting stability and low cutting forces, meanwhile friction and normal force reduced by around 15% and 10%, respectively with a weak correlation to the grooves’ orientation. High density VLT tools, on the other hand, presented an obvious anti-adhesion property. A 5 µm reduction of crater wear’s depth can be observed on textured rake faces after long length cutting and textured rake faces presented half size of BUE regions comparing to the flat tool, however, once the texture morphologies were filled or worn, the anti-adhesion effect could be invalid. The bearing ratio curve was employed to analysis tool-chip contact and durability of textured surfaces contributing to a better understanding of anti-adhesion and enhanced durability of the textured tools.
Temperature-Dependent Photovoltaic Characterization of a CdTe/CdSe Nanocrystal’s Solar Cell
Huichao Zhang,Zhengyang Li,Jun Qian,Qiumei Guan,Xiaowei Du,Yiping Cui,Jiayu Zhang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
An all-inorganic thin film solar cell was fabricated with colloidal CdTe and CdSe nanocrystals. Its temperaturedependent photovoltaic characterization was measured, and an open circuit voltage decay technique was used to determine the electron lifetime. The photovoltaic parameters, such as the exact carrier lifetime, were remarkably different between under low-temperature region and under temperature above 267 K. It is suggested that the temperature-dependent carrier conductivity results from a thermally-activated hopping process and this nanocrystals device is a kind of donor-acceptor solar cell.
Mingyao Song,Zhengyang Duan,Ronggao Qin,Xiaojun Xu,Shuli Liu,Shumin Song,Mengjiao Zhang,Yue Li,Jiemei Shi 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.6
Xanthate-modified baker’s yeast (XMBY) was successfully synthesized by grafting xanthate groups onto the surface of baker’s yeast and was used for the simultaneous adsorption of cadmium (Cd2+) and methylene blue (MB) from aqueous solution. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the synthesized adsorbent. The results indicated that the sulfur groups were successfully introduced onto the surface of the baker’s yeast and participated in the adsorption processes. The kinetic and isotherm data showed good correlations with the pseudo-second-order model and the Langmuir model, respectively. The equilibrium time and the maximum values obtained from the two models were 40 min, 239.8mg/g for Cd2+ and 300 min, 64.45mg/g for MB, respectively. The thermodynamic analysis (G<0, H>0, S>0) demonstrated that the adsorption processes of Cd2+ and MB onto the XMBY were endothermic and spontaneous. In the binary-component solution (Cd2+ and MB), the adsorption capacity for MB was almost unaffected by the presence of Cd2+ and interestingly, the adsorption capacity for Cd2+ increased in the presence of MB. Overall, these results indicated that XMBY could be a promising adsorbent for the treatment of wastewater containing both Cd2+ and MB.
Novel Hierarchical TiO2/C Nanocomposite with Enhanced Photocatalytic Performance
Yupeng Gao,Hao Chen,Aiguo Zhou,Zhengyang Li,Fanfan Liu,Qianku Hu,Libo Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5
"Hierarchical TiO2 /carbon nanocomposites were synthesized by oxidation of two-dimensional(2D) Ti3C2 nanosheets at different temperatures. Crystal structures and morphologies of the obtained samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy. The results show that 2D Ti3C2 nanosheets are partially oxidized to form a novel hierarchical nanostructure which is composed of carbon nanosheets and TiO2 nanoparticles. With the calcination temperature increasing, the crystal structure of TiO2 nanoparticles changes from anatase to rutile and the hierarchical structure was gradually destroyed. The photodegradation results reveal that the samples obtained at 200℃ and 285℃ show much better photocatalytic properties than P25. And meanwhile the photocatalytic property will become worse with the increase in calcinations temperature."