Photocatalytic H₂ Evolution Coupled with Degradation of Plastic

Kan Zhang 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

Spatial Nanoarchitectonics Design of Two-Dimensional Transition-Metal Dichalcogenides Nanosheets for High-performance Sodium Storage

( Kan Zhang ) 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Sodium-ion batteries (SIBs) have emerged as a promising candidate for large-scale stationary energy storage in light of possible concerns over cost and abundance. Advanced sodium host materials are required for developing SIBs with high energy density, long cycling stability and high safety. Layered metal dichalcogenides (MX2, M = Mo, W; X= S, Se) have become a hot spot for anode materials in SIBs due to their logical component and high theoretical capacity. However, the sluggish Na+ diffusion kinetics lead to poor electrochemical behaviours. In this talk, I will present an emphasis that is placed on enhancing the electrochemical Na+ storage performance through spatial nanoarchitectonics design, including vertical alignment, interlayer engineering and orientation stacking. It is hoped that light is shed on the further development of SIBs in view of their high capacity, long-term stability and volumetric energy density.

Effect of Heat-Treated Temperature on Surface Crystal Structure and Catalytic Activity of ACF/ZnO Composite under Ultraviolet Irradiation and Ultrasonication

Kan Zhang,오원춘 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.2

ACF/ZnO photocatalyst was synthesized by a sol-gel method using activated carbon fiber (ACF) and Zn (NO3)2 as precursors. Samples were characterized by Brunauer-Emmett-Teller measurements (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The XRD results showed that ACF/ZnO composites only included a hexagonal phase by heat-treated temperature at 400oC, 500oC, 600oC, and 700oC. The SEM analysis revealed that the ACF/ZnO composites did not exhibit any morphological changes of the catalyst surface according to the different heat-treated temperatures. The photocatalytic activity of the samples was tested for degradation of methylene blue (MB) solutions under ultraviolet (UV) light and ultrasonication respectively. The results showed that the photocatalytic activity of ACF/ZnO composites heat-treated at 500oC was higher than other samples, which is ascribed to the fine distribution of ZnO particles on the surface of the ACF. In addition, an ultrasound of low power (50 W) was used as an irradiation source to successfully induce ACF/ZnO composites to perform sonocatalytic degradation of MB. Results indicated that the sonocatalytic method in the presence of ACF/ZnO composites is an advisable choice for the treatments of organic dyes.

Photodecomposition of Different Organic Dyes Using Fe-CNT/TiO2 Composites under UV and Visible Light

Kan Zhang,Ze-Da Meng,오원춘 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.2

The Fe-treated CNT/TiO2 photocatalysts mixed with anatase and rutile phase have been developed for the decomposition of non-biodegradable different organic dyes like methylene blue (MB), rhodamine B (Rh.B), and methyl orange (MO) in two conditions as ultraviolet and visible light respectively. The results indicate that all the Fe-CNT/TiO2 composites proved to be more efficient photocatalysts since degradation of MB at higher reaction rates, tthe decomposition rate of different dyes increases with an increase of Fe3+ concentration in composites the highest rate of decomposition of different dyes was noted under UV irradiation. These results can indicate that the large CNT network is facilitate the electron transfer and strongly adsorb dye molecules on the texted photocatalysts, iron is reactive in the photo-Fenton process resulting in high production of OH radicals and also high activity of the photocatalyst. And Fe particles can generate more photoinduced electrons to conduction band of TiO2 under visible light irradiation. The composites of Fe-CNT/TiO2 photocatalysts synthesized by a sol-gel method were characterized by BET, TEM, SEM, XRD and EDX.

The Photocatalytic Decomposition of Different Organic Dyes under UV Irradiation with and without H₂O₂ on Fe-ACF/TiO₂ Photocatalysts

Kan Zhang,Won-Chun Oh 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6

The Fe-ACF/TiO₂ composites were prepared by a sol-gel method and were characterized by nitrogen adsorption, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Energy Dispersive X-ray (EDX). The Fe-CF/TiO₂ composites were developed for the decomposition of organic dyes by using a UV lamp. The decomposition effect was investigated under various conditions, such as three selected non-biodegradable organic dyes like Methylene Blue (MB), Methyl Orange (MO), Rhodamine B (Rh.B), and in the presence of Fe and hydrogen peroxide (H₂O₂). The photocatalytic activity was derived from possible combination effects, such as (1) adsorption of ACF, (2) generation of electron/hole by TiO₂, (3) photo-nton reaction of Fe, and (4) oxidation of Fe2+ to Fe3+ by H₂O₂.

Photonic Aspects of MB Degradation on Fe-carbon/TiO2 Composites under UV Light Irradiation

Kan Zhang,Ze-Da Meng,오원춘 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.5

Fe-carbon/TiO2 composites were prepared by a sol-gel method using AC, ACF, CNT and C60 as carbon precursors and were characterized by means of BET surface area, X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The activity of the prepared photocatalysts was investigated by degradation reaction of methylene blue (MB) irradiated with UV lamp. Effects of different carbon sources and irradiation time on photocatalytic activity were also investigated. The results showed that the photocatalytic activity of the Fe-carbon/TiO2 composites was much higher than that of pristine TiO2 and Fe/TiO2 composites. The prominent photocatalytic activity of Fecarbon/TiO2 composites could be attributed to both the effects of photo-adsorption and electron transfer by carbon substrate. In addition, the higher photocatalytic activity of Fe-carbon/TiO2 composites can be compared with that of carbon/TiO2 and Fe /TiO2 composites due to cooperative effects between Fe and carbon.

Kinetic Study of the Visible Light-Induced Sonophotocatalytic Degradation of MB Solution in the Presence of Fe/TiO2-MWCNT Catalyst

Kan Zhang,오원춘 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.6

In order to effective degradation of organic dye both under visible light or ultrasonic irradiation, the MWCNTs (multiwalled carbon nanotube) deposited with Fe and TiO2 were prepared by a modified sol-gel method. The Fe/TiO2-MWCNT catalyst was characterized by surface area of BET, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) and ultraviolet-visible (UV-vis)spectroscopy. The low intensity visible light and low power ultrasound was as an irradiation source and the methylene blue (MB) was choose as the model organic dye. Then degradation experiments were carried out in present of undoped TiO2, Fe/TiO2 and Fe/TiO2-MWCNT catalysts. Through the degradation of MB solution, the results showed the feasible and potential use of Fe/TiO2-MWCNT catalyst under visible light and ultrasonic irradiation due to the enhanced formation of reactive radicals as well as the possible visible light and the increase of ultrasound-induced active surface area of the catalyst. After addition of H2O2, the MB degradation rates have been accelerated, especially with Fe/TiO2-MWCNT catalyst, in case of that the photo-Fenton reaction occurred. The sonophotocatalysis was always faster than the respective individual processes due to the more formation of reactive radicals as well as the increase of the active surface area of Fe/TiO2-MWCNT catalyst.

Conformal coating strategy comprising N-doped carbon and conventional graphene for achieving ultra-high power and cyclability of LiFePO4

( Liping ),( Kanzhang ),박종혁 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Surface carbon coating to improve the inherent poor electrical conductivity of lithium iron phosphate (LiFePO4, LFP) has been considered as most efficient strategy. Here, we also report one of the conventional methods for LFP, but exhibiting a specific capacity beyond the theoretical value, ultra-high rate performance, and excellent long-term cyclability: the specific capacity is 171.9 mAh/g (70 μm-thick electrode with ~10 mg/cm2 loading mass) at 0.1 C (17 mA/g), and retains 143.7 mAh/g at 10 C (1.7 A/g) and 95.8 % of initial capacity at 10 C after 1000 cycles. It was found that the interior conformal N-C coating enhances the intrinsic conductivity of LFP nanorods (LFP NR) and the exterior RGO coating acts as an electrically conducting secondary network to electrically connect the entire electrode. The great electron transport mutually promoted with shorten Li diffusion length on (010) facet exposed LFP NR represents the highest specific capacity value recorded to date at 10C and ultra-long-term cyclability. This conformal carbon coating approach can be a promising strategy for the commercialization of LFP cathode in lithium ion batteries.