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RISS 인기검색어
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- 저자 : Sennu, Palanichamy (검색결과 4 건)
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Sennu, Palanichamy,Park, Hyo Seok,Park, Kwang Uk,Aravindan, Vanchiappan,Nahm, Kee Suk,Lee, Yun-Sung Elsevier 2017 Journal of catalysis Vol.349 No.-
<P><B>Abstract</B></P> <P>A 3D structured NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid was prepared by a two-step hydrothermal approach and subsequently employed as a highly efficient catalyst in oxygen reduction reactions (ORRs)/oxygen evolution reactions (OERs) and from a Li–O<SUB>2</SUB> battery perspective. The Co-NC possesses interconnected NiCo<SUB>2</SUB>O<SUB>4</SUB> nanorods grown over a Co<SUB>3</SUB>O<SUB>4</SUB> nanosheet structure, which facilitates charge transfer and enhances the electrical conductivity. Moreover, the 3D structured hybrids are directly used as a cathode catalyst for the Li–O<SUB>2</SUB> system and displayed a maximum in-depth-specific discharge capacity of 4386mAhg<SUP>−1</SUP>. In addition, significantly improved and stable cycling performance up to 60 cycles is observed compared with Co<SUB>3</SUB>O<SUB>4</SUB> nanosheets at the limited capacity range of 500mAhg<SUP>−1</SUP>. The excellent electrochemical performance of the NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid is mainly associated with the oxygen-deficient 3D architecture providing more catalytic active sites and can accommodate more discharge products. Further, ORR/OER activities of NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid in aqueous media are also evaluated in 0.1M KOH solution using the rotating ring disk electrode technique. For instance, the OER activity of NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid (apex current is 4.18mAcm<SUP>−2</SUP>) is an approximately 2.25 times higher than that of commercial RuO<SUB>2</SUB> catalyst (1.84mAcm<SUP>−2</SUP>). Since the catalytic activity in aqueous and organic medium is not necessarily the same, but of NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid exhibiting excellent ORR/OER characteristics in both cases is worth mentioning.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D structured NiCo<SUB>2</SUB>O<SUB>4</SUB>@Co<SUB>3</SUB>O<SUB>4</SUB> hybrid is prepared as catalyst for Li-O<SUB>2</SUB> battery. </LI> <LI> Excellent ORR/OER activity is observed in both aqueous and organic media. </LI> <LI> Li–O<SUB>2</SUB> system displayed a maximum in-depth-specific discharge capacity of 4386mAhg<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Sennu, P.,Aravindan, V.,Lee, Y.S. Elsevier Sequoia 2016 Journal of Power Sources Vol.306 No.-
We report the fabrication of high energy asymmetric supercapacitor (ASC) using pseudocapacitive 3D microstructured composite NiCo<SUB>2</SUB>O<SUB>4</SUB>Γo<SUB>3</SUB>O<SUB>4</SUB> and double layer forming activated carbon (AC). The pseudo capacitive electrode is synthesized via a facile two step hydrothermal process and AC is obtained from the bio-waste, Jackfruit (JF) peel by chemical activation. Extensive powder characterization and optimization has been conducted for both electrodes, especially in electrochemical aspect. The ASC is fabricated using JF derived AC as anode and NiCo<SUB>2</SUB>O<SUB>4</SUB>Γo<SUB>3</SUB>O<SUB>4</SUB> cathode in aqueous media. Prior to the ASC assembly, the mass loading between the electrodes are adjusted based on the single electrode performance of both components vs. Ag/AgCl. The ASC is capable of delivering a maximum energy density of 42.5 Wh kg<SUP>-1</SUP> at power density of 80 W kg<SUP>-1</SUP>. In addition, the ASC rendered excellent cycleability, for example, the cell retains ~97% of initial capacitance after 7000 cycles. The outstanding performance of the ASC is originated from the well-developed building blocks of porous electrodes. An impedance study is also conducted to corroborate the excellent performance of NiCo<SUB>2</SUB>O<SUB>4</SUB>Γo<SUB>3</SUB>O<SUB>4</SUB>vs. JF derived AC based ASC.
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Sennu, Palanichamy,Kim, Hyo Sang,An, Jae Youn,Aravindan, Vanchiappan,Lee, Yun-Sung Wiley-VCH 2015 Chemistry - An Asian Journal Vol.10 No.8
<P>Mesoporous Co3O4 nanosheets (Co3 O4 -NS) and nitrogen-doped reduced graphene oxide (N-rGO) are synthesized by a facile hydrothermal approach, and the N-rGO/Co3O4 -NS composite is formulated through an infiltration procedure. Eventually, the obtained composites are subjected to various characterization techniques, such as XRD, Raman spectroscopy, surface area analysis, X-ray photoelectron spectroscopy (XPS), and TEM. The lithium-storage properties of N-rGO/Co3O4 -NS composites are evaluated in a half-cell assembly to ascertain their suitability as a negative electrode for lithium-ion battery applications. The 2D/2D nanostructured mesoporous N-rGO/Co3O4 -NS composite delivered a reversible capacity of about 1305 and 1501???mAh???g(-1) at a current density of 80???mA???g(-1) for the 1st and 50th???cycles, respectively. Furthermore, excellent cyclability, rate capability, and capacity retention characteristics are noted for the N-rGO/Co3O4 -NS composite. This improved performance is mainly related to the existence of mesoporosity and a sheet-like 2D hierarchical morphology, which translates into extra space for lithium storage and a reduced electron pathway. Also, the presence of N-rGO and carbon shells in Co3O4 -NS should not be excluded from such exceptional performance, which serves as a reliable conductive channel for electrons and act as synergistically to accommodate volume expansion upon redox reactions. Ex-situ TEM, impedance spectroscopy, and XPS, are also conducted to corroborate the significance of the 2D morphology towards sustained lithium storage.</P>
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Lee, Si-Hwa,Kotal, Moumita,Oh, Jung-Hwan,Sennu, Palanichamy,Park, Sung-Ho,Lee, Yun-Sung,Oh, Il-Kwon Elsevier 2017 Carbon Vol.119 No.-
<P>Graphene hybrid nanostructures have emerged as potential candidates as efficient anode materials for lithium-ion batteries. However, two-dimensional plate-like structures protect rapid transport of lithium ions through the thickness direction, resulting in a long pathway of lithium ions and low rate performances. Here, we report a nanohole-structured, iron oxide-decorated and gelatin-functionalized graphene (D-N-GG) for high rate and high capacity lithium-ion anode. Initially, to produce effective path way of lithium ions, physical nanoholes on the graphene layers were generated by microwave-irradiated iron nanoparticles. And then, the gelatin was used to form nitrogen-doped graphene having more active sites for lithium ion storage. Finally, D-N-GG was synthesized by two-step microwave irradiations shows a three-dimensional interconnected mesoporous structure with a uniform decoration of iron oxide nanoparticles on the nanohole-structured graphene, resulting in highly conductive networks and short diffusion lengths for effective lithium ion transport. As a result, the obtained D-N-GG nanostructure delivered a reversible capacity of 924 mAh g(-1) even over 40 cycles along with a coulombic efficiency in excess of 99%. Especially, even after 65 cycles with variable current density of 100-800 mA g(-1), the discharge capacity returned to 1096 mAh g(-1), which indicated a very stable and high-rate cyclic performance. (C) 2017 Elsevier Ltd. All rights reserved.</P>
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