Study on Improvement of Properties for Epoxidized Natural Rubber by Addition of Starch and Molybdenum Disulfide

Xu Chen(진욱),Xiang Xu Li(리시앙수),Ur Ryong Cho(조을룡) 한국고분자학회 2018 폴리머 Vol.42 No.6

Epoxidized natural rubber(ENR)에 전분과 이황화몰리브덴이 다양한 비율로 혼합되었다. 제조된 복합체의 경화 물성과 동적점탄성은 고무 가공 분석기로 측정되었고, 시료의 형태학적 구조는 SEM으로 확인되었다. 기계적 물성, 열분해성, 인장강도, 경도, 마찰계수, 내마모성, 팽윤율도 물성 향상을 확인하기 위하여 조사되었다. 모든 실험결과에서, 충전제-충전제 상호작용은 전분 함량이 증가함에 따라 향상되었음을 알 수 있었다. 그리고 기계적 물성도 따라 향상되었다. 그 원인은 전분과 ENR 고무 사이에 수소 결합이라는 더 나은 결합의 형성이었다. 또한 이황화몰리브덴의 첨가에 따라, 고무복합에의 윤활성이 증가되어 마찰계수와 내마모성이 개선됨을 알 수 있었다. Epoxidized natural rubber (ENR) was filled with starch and molybdenum disulfide (MoS2) on different ratios. The curing properties and viscoelastic behavior of the composites was tested by rubber processing analyzer, and the morphological structure of the composites samples were characterized by SEM. The mechanical properties, the thermal decomposition behavior, tensile strength, hardness value, friction coefficient, abrasion resistance and swelling ratio were investigated to verify the property improvement of the ENR composites. From the results of all the tests, it can be found that the intermolecular interaction increased with increasing starch content. And the mechanical properties also increased. The possible reason may be the starch could provide the better combination with ENR rubber matrix due to the hydrogen bonding. And with the addition of molybdenum disulfide, the friction coefficient and abrasion resistance properties were improved due to the lubrication of molybdenum disulfide.

In-situ Detection of Phenols using Molybdenum Disulfide-Based Hydrogels

김현수,이도훈,김태완,박규열,이병양 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.5

Free-standing molybdenum disulfide/graphene composite paper as a binder- and carbon-free anode for lithium-ion batteries

Yang, MinHo,Ko, Seunghyun,Im, Ji Sun,Choi, Bong Gill Elsevier 2015 Journal of Power Sources Vol.288 No.-

<P><B>Abstract</B></P> <P>Two dimensional nanosheets, such as graphene and metal disulfides, have attracted a great deal of attention as anode materials for lithium-ion batteries, owing to their unique capability for lithium-ion storage. In this work, we integrate graphene and MoS<SUB>2</SUB> nanosheets into a free standing film form using a simple vacuum filtration method. As-prepared composite film could be readily employed as a binder- and carbon-free anode for lithium-ion batteries, removing the polymeric binders and conductive carbon additives that are required for the preparation of conventional electrodes. In addition, the interconnected structure of graphene and MoS<SUB>2</SUB> sheets provide a good electrical conductivity to the entire film electrode. When tested electrochemical performance as an anode for lithium-ion batteries, the composite film electrode exhibits superior performance compared to the exfoliated MoS<SUB>2</SUB> electrode, such as 65.8% capacity retention at a high current rate of 1000 mA g<SUP>−1</SUP> and 91.1% capacity retention after 100 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A free-standing MoS<SUB>2</SUB>/graphene (MoS<SUB>2</SUB>/G) composite paper was prepared by a simple vacuum filtration method. </LI> <LI> HADDF-STEM image revealed an alternatively layered structure of MoS<SUB>2</SUB>/G composite paper. </LI> <LI> MoS<SUB>2</SUB>/G paper significantly improved the Li<SUP>+</SUP> ion storage/release process, compared to the exfoliated MoS<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

High-yield preparation of molybdenum disulfide/polypyrrole hybrid nanomaterial with non-covalent interaction and its supercapacitor application

전호윤,방민지,최민석,신근영 한국공업화학회 2021 한국공업화학회 연구논문 초록집 Vol.2021 No.0

A route to synthesis molybdenum disulfide-reduced graphene oxide (MoS₂-RGO) composites using supercritical methanol and their enhanced electrochemical performance for Li-ion batteries

Choi, Mugyeom,Koppala, Siva Kumar,Yoon, Dohyeon,Hwang, Jieun,Kim, Seung Min,Kim, Jaehoon Elsevier 2016 Journal of Power Sources Vol.309 No.-

<P><B>Abstract</B></P> <P>A simple and effective approach for the tight anchoring of molybdenum disulfide (MoS<SUB>2</SUB>) to the surface of supercritical-alcohol-reduced graphene oxide (SRGO) is developed. The MoS<SUB>2</SUB>-SRGO composites are synthesized by the one-pot deposition of MoO<SUB>2</SUB> on SRGO and simultaneous reduction of GO to SRGO in supercritical methanol followed by sulfurization. The obtained MoS<SUB>2</SUB>-SRGO composites contain a crystalline MoS<SUB>2</SUB> phase comprising 11–14 layers of MoS<SUB>2</SUB>. In addition, the composites have mesoporous structures with high porosities, ranging between 55 and 57%. In comparison with bare MoS<SUB>2</SUB> and SRGO, the MoS<SUB>2</SUB>-SRGO composites have enhanced electrochemical performances due to their mesoporous structures and the synergetic effect between MoS<SUB>2</SUB> and SRGO sheets. When tested as the anode in a secondary lithium battery, it shows high reversible capacity of 896 mAh g<SUP>−1</SUP> at 50 mA g<SUP>−1</SUP> after 50 cycles, a high rate capacity of 320 mAh g<SUP>−1</SUP> at a high charge-discharge rate of 2.5 A g<SUP>−1</SUP>, and long-term cycling of 724 mAh g<SUP>−1</SUP> at 50 mA g<SUP>−1</SUP> after 200 cycles. This unique synthetic approach effectively and tightly anchors MoS<SUB>2</SUB> nanoparticles to the SRGO surface, resulting in improved structural integrity, electron transfer efficiency between the SRGO sheets and MoS<SUB>2</SUB>, and Li-ion diffusion kinetics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple supercritical methanol route is used for tight anchoring of MoS<SUB>2</SUB> to RGO. </LI> <LI> RGO prevents restacking of MoS<SUB>2</SUB> layer, resulting in mesoporous structure. </LI> <LI> The MoS<SUB>2</SUB>–RGO composite exhibits reversible capacity of 896 mA g<SUP>−1</SUP> at 50 mA g<SUP>−1</SUP>. </LI> <LI> Charge transfer kinetics of MoS<SUB>2</SUB>–RGO improved an order of magnitude than bare MoS<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

One-pot synthesis of molybdenum disulfide–reduced graphene oxide (MoS₂-RGO) composites and their high electrochemical performance as an anode in lithium ion batteries

Choi, Mugyeom,Hwang, Jieun,Setiadi, Handi,Chang, Wonyoung,Kim, Jaehoon Elsevier science 2017 The Journal of supercritical fluids Vol.127 No.-

<P><B>Abstract</B></P> <P>A simple, effective, and ultra-fast one-pot route is developed to synthesize molybdenum disulfide (MoS<SUB>2</SUB>)-reduced graphene oxide (RGO) composites. The method to tightly anchor MoS<SUB>2</SUB> particles on the surface of RGO includes simultaneous reduction of graphene oxide (GO) and heterogeneous nucleation and growth of MoS<SUB>2</SUB> on the RGO surface in supercritical ethanol (scEtOH) medium. The synthesized MoS<SUB>2</SUB>-RGO composites have a mesoporous structure with high porosity. The MoS<SUB>2</SUB>-RGO composites show an enhanced electrochemical performance due to their unique nanostructure and the synergetic effect of MoS<SUB>2</SUB> and RGO nanosheets when compared to those of compared with bare MoS<SUB>2</SUB> and bare RGO. The MoS<SUB>2</SUB>-RGO composite with a MoS<SUB>2</SUB> loading of 74.0wt% can deliver a high reversible discharge capacity up to 1102mAhg<SUP>−1</SUP> at a rate of 0.05Ag<SUP>−1</SUP> after 80 cycles and an excellent cycling stability of 951mAhg<SUP>−1</SUP> at 0.05Ag<SUP>−1</SUP> after 140 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> One-pot, fast, green supercritical ethanol route to synthesize MoS<SUB>2</SUB>-RGO composites. </LI> <LI> MoS<SUB>2</SUB> is tightly anchored and uniformly deposited on the RGO surface. </LI> <LI> MoS<SUB>2</SUB>-RGO exhibits mesoporous structure with high porosity and conductivity. </LI> <LI> MoS<SUB>2</SUB>-RGO exhibits high reversible capacity of 1102mAg<SUP>−1</SUP> at 50mAg<SUP>−1</SUP>. </LI> <LI> Excellent high-rate performance of 469mAhg<SUP>−1</SUP> at 2.5Ag<SUP>−1</SUP> resulted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

One-step construction of a molybdenum disulfide/multi-walled carbon nanotubes/polypyrrole nanocomposite biosensor for the <i>ex-vivo</i> detection of dopamine in mouse brain tissue

Vijayaraj, Kathiresan,Dinakaran, Thirumalai,Lee, Yujeong,Kim, Suhkmann,Kim, Hyung Sik,Lee, Jaewon,Chang, Seung-Cheol Elsevier 2017 Biochemical and biophysical research communication Vol. No.

<P><B>Abstract</B></P> <P>We developed a new strategy for construction of a biosensor for the neurotransmitter dopamine. The biosensor was constructed by one-step electrochemical deposition of a nanocomposite in aqueous solution at pH 7.0, consisting of molybdenum disulfide, multi-walled carbon nanotubes, and polypyrrole. A series of analytical methods was performed to investigate the surface characteristics and the improved electrocatalytic effect of the nanocomposite, including cyclic voltammetry, electrochemical impedance spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. The constructed biosensor showed high sensitivity (1.130 μAμM<SUP>−1</SUP>cm<SUP>−2</SUP>) with a dynamic linearity range of 25–1000 nM and a detection limit of 10 nM. Additionally, the designed sensor exhibited strong anti-interference ability and satisfactory reproducibility. The practical application of the sensor was manifested for the <I>ex vivo</I> determination of dopamine neurotransmitters using brain tissue samples of a mouse Parkinson's disease model.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ex vivo dopamine detection in mouse brain tissues of Parkinson's disease model. </LI> <LI> Nanocomposite constructed by one-step electrochemical approach. </LI> <LI> The synergetic performance enhancement of the sensor by nanocomposite. </LI> </UL> </P>

Unconventional pore and defect generation in molybdenum disulfide: application in high-rate lithium-ion batteries and the hydrogen evolution reaction.

Zhang, Kan,Kim, Hwan-Jin,Lee, Jeong-Taik,Chang, Gee-Woo,Shi, Xinjian,Kim, Wanjung,Ma, Ming,Kong, Ki-jeong,Choi, Jae-Man,Song, Min-Sang,Park, Jong Hyeok Wiley-VCH 2014 ChemSusChem Vol.7 No.9

<P>A 2H-MoS2 (H=hexagonal) ultrathin nanomesh with high defect generation and large porosity is demonstrated to improving electrochemical performance, including in lithium-ion batteries (LIBs) and the hydrogen evolution reaction (HER), with the aid of a 3D reduced graphene oxide (RGO) scaffold as fast electron and ion channels. The 3D defect-rich MoS2 nanomesh/RGO foam (Dr-MoS2 Nm/RGO) can be easily obtained through a one-pot cobalt acetate/graphene oxide (GO) co-assisted hydrothermal reaction, in which GO, cobalt and acetate ions are co-morphology-controlling agents and defect inducers. As an anode material for LIBs, Dr-MoS2 Nm/RGO has only a 9% capacity decay at a 10?C discharge rate versus 0.2?C with stable cyclability at the optimized composition (5?wt% RGO to MoS2 and 2?mol% Co to Mo), and significantly achieves 810?mA?h?g(-1) at a high current density of 9.46?A?g(-1) over at least 150?cycles. Moreover, Dr-MoS2 Nm/RGO exhibits superior activity for the HER with an overpotential as low as 80?mV and a Tafel slope of about 36?mV per decade. In contrast to the MoS2 nanosheet/RGO (MoS2 Ns/RGO), which is synthesized in the absence of cobalt ions, Dr-MoS2 Nm/RGO provides high interconnectivity for efficient lithium-ion transport, and rich defects as electrochemically active sites. DFT is used to prove the existence of rich defects due to anion replacement to become a Co-Mo-S atomic structure, releasing inert basal planes to active sites.</P>

Ultralow Schottky Barrier Height Achieved by Using Molybdenum Disulfide/Dielectric Stack for Source/Drain Contact

Kim, Seung-Hwan,Han, Kyu Hyun,Park, Euyjin,Kim, Seung-Geun,Yu, Hyun-Yong American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.37

<P>Energy barrier formed at a metal/semiconductor interface is a critical factor determining the performance of nanoelectronic devices. Although diverse methods for reducing the Schottky barrier height (SBH) via interface engineering have been developed, it is still difficult to achieve both an ultralow SBH and a low dependence on the contact metals. In this study, a novel structure, namely, a metal/transition-metal dichalcogenide (TMD) interlayer (IL)/dielectric IL/semiconductor (MTDS) structure, was developed to overcome these issues. Molybdenum disulfide (MoS<SUB>2</SUB>) is a promising TMD IL material owing to its interface characteristics, which yields a low SBH and reduces the reliance on contact metals. Moreover, an ultralow SBH is achieved via the insertion of an ultrathin ZnO layer between MoS<SUB>2</SUB> and a semiconductor, thereby inducing an n-type doping effect on the MoS<SUB>2</SUB> IL and forming an interface dipole in the favorable direction at the ZnO IL/semiconductor interfaces. Consequently, the lowest SBH (0.07 eV) and a remarkable improvement in the reverse current density (by a factor of approximately 5400) are achieved, with a wide room for contact-metal dependence. This study experimentally and theoretically validates the effect of the proposed MTDS structure, which can be a key technique for next-generation nanoelectronics.</P> [FIG OMISSION]</BR>

이황화몰리브덴을 촉매로 활용한 막 전극 조립체 열 압축 최적화에 대한 연구

오종현 ( Jonghyeon Oh ),김진선 ( Jinsun Kim ),김기범 ( Kibum Kim ) 충북대학교 산업과학기술연구소 2022 산업과학기술연구 논문집 Vol.36 No.2

Recently, Proton Exchange Membrane Electrolyzer Cell (PEMEC) is drawing attention as a hydrogen energy production device. However, the high price of platinum used as a catalyst for the Gas Diffusion Electrode (GDE), which is one of the components of PEMEC, is making it difficult to commercialize. Therefore, the use of alternative catalysts in GDE and the optimization of membrane electrode assembly (MEA), which is a combination of GDE, are essential. Accordingly, the MEA was optimized using a hot pressing method as a catalyst molybdenum disulfide. The experiment was carried out under 8 conditions using the 2³ design of experiment method. In order to fabricate the MEA, an experiment was conducted using the main parameters of hot pressing, such as process time, pressure, and temperature, as variables. The temperature was set to 100-120℃, the pressure was 35-105 bar, and the process time was 1-3 minutes. After hot pressing, cyclic voltammetry was performed 10 times for stabilization, and then the current density was measured through chromoamperometry. Based on this, the main effects and interaction effects of major variables were analyzed through minitap software. As a result of the analysis, it was confirmed that temperature had the most major influence on performance, and the optimal conditions were 100℃, 35 bar, and 1 minute. These studies are expected to have an impact on the activation of various types of catalyst research that will be applied to PEMEC in the future.