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Ko, Dongjin,Jin, Xuanzhen,Seong, Kwang-dong,Yan, Bingyi,Chai, Hua,Kim, Jong Min,Hwang, Minsik,Choi, Juhyung,Zhang, Wang,Piao, Yuanzhe Elsevier 2019 Applied catalysis. B, Environmental Vol.248 No.-
<P><B>Abstract</B></P> <P>MoS<SUB>2</SUB> has been considered as a non-precious alternative to platinum based electrocatalyst for electrochemical hydrogen evolution. Since most of the active site exists on the edges of MoS<SUB>2</SUB>, a material design that could increase the exposure of the edges could improve its catalytic activity. In this work, we prepared small sized and few-layered MoS<SUB>2</SUB> that is vertically aligned on three-dimensional interconnected porous carbon nanosheets (IPC). Benefiting from exposure of MoS<SUB>2</SUB> edges, MoS<SUB>2</SUB>/IPC composite exhibits a high catalytic activity (225 mA cm<SUP>−2</SUP> at −250 mV vs. RHE, and Tafel slope of 38 mV dec<SUP>−1</SUP>) and maintains steady performance for several hours. Since the procedure to prepare MoS<SUB>2</SUB>/IPC composites is scalable and cost-effective, our method of preparing few-layered MoS<SUB>2</SUB> on porous carbon shows great potential as a competitive electrocatalysts for HER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Few-layered MoS<SUB>2</SUB> are deposited onto 3D interconnected porous carbon nanosheets to increase the exposure of active edges. </LI> <LI> The MoS<SUB>2</SUB> are vertically aligned on the 3D interconnected porous carbon nanosheets through a solvothermal method. </LI> <LI> The obtained nanocomposite shows an excellent catalytic activity in HER. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Preparation and Microwave Absorption Properties of the Fe/TiO2/Al2O3 Composites
Yun Li,Haifeng Cheng,Nannan Wang,Shen Zhou,Dongjin Xie,Tingting Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.11
To reduce the imbalance of impedance matching between the magnetic metal nanowires and free space, Fe/TiO2 core/shell nanowire arrays with different diameters were fabricated in the templates of anodic aluminum oxide membranes by electrodeposition. The influences of the microstructure on the microwave absorption properties of the Fe/TiO2/Al2O3 composites were studied by the transmission/reflection waveguide method. It was demonstrated experimentally that both the interfacial polarization and the diameter of the Fe/TiO2 core/shell nanowires have critical effects on the microwave absorption properties. We also investigated the angle dependence of the microwave absorption properties. Due to the interfacial polarization and associated relaxation, the Fe/TiO2/Al2O3 composites exhibited optimal microwave absorption properties when microwave propagation direction was accordant with the axis of the nanowires. Finally, we managed to obtain an optimal reflection loss of below -10 dB (90% absorption) over 10.2–14.8 GHz, with a thickness of 3.0mm and the minimum value of -39.4 dB at 11.7 GHz.
Coexistence of OSCR-Based IR-UWB System with IEEE 802.11a WLAN
Weiwei Wu,Han Huang,Huarin Yin,Weidong Wang,Dongjin Wang 한국전자통신연구원 2006 ETRI Journal Vol.28 No.1
Impulse radio (IR) is a competitive candidate for ultra-wideband (UWB) systems. In this letter, we evaluated the coexistence of an IR-UWB system based on an orthogonal sinusoidal correlation receiver (OSCR) with an IEEE 802.11a WLAN through a detailed simulation. The coexistence performance of the two systems is characterized in terms of the receiver’s bit-error rates. Then, some approaches to interference mitigation are discussed.