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최교훈,백운철,임승만,박정태 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Herein, we incorporated cobalt-iron layered double hydroxide with metal-organic framework derived cobalt phosphide via electrodeposition on carbon cloth. The synthesized CoP@CoFe hierarchical heterostructures exhibited not only possessing high surface area due to the MOF nature, also showed OER, and HER responsive without using any binder on carbon cloth substrate. The prepared electrode was applied to overall water splitting in 1 M KOH, and the overpotentials to reach current density of 10 mA cm<sup>-2</sup> were 270, 172 mV, respectively. The CoP@CoFe hierarchical heterostructures show excellent electrocatalytic activities toward both OER and HER in an alkaline media, attributed to the synergistic effect such as reduced series resistance and increased catalytic active site. Moreover, the catalytic activity was not degraded even after a long operation of more than 50 h.
Yutkin, M.P.,Zavakhina, M.S.,Samsonenko, D.G.,Dybtsev, D.N.,Fedin, V.P. Elsevier Sequoia [etc.] 2013 Inorganica chimica acta Vol.394 No.-
Three new homochiral metal-organic frameworks (MOFs) based on malate anions and N-donor linkers of different length have been prepared. [Co<SUB>2</SUB>(mal)<SUB>2</SUB>(bpy)].2H<SUB>2</SUB>O (1), [Ni<SUB>2</SUB>(mal)<SUB>2</SUB>(bpy)].2H<SUB>2</SUB>O (2), [Ni<SUB>2</SUB>(mal)<SUB>2</SUB>(bpe)].3H<SUB>2</SUB>O (3) (mal=S-malate, bpy=4,4'-bipyridyl, bpe=trans-1,2-bis(4-pyridyl)ethylene) were characterized by a number of analytical methods including single crystal X-ray analysis. Optical purity of compounds 2 and 3 was confirmed by polarimetry experiments. Compounds 1 and 2 contribute to the family of isoreticular M(II) malates and aspartates ([M<SUB>2</SUB>(asp)<SUB>2</SUB>L] and [M<SUB>2</SUB>(mal)<SUB>2</SUB>L], M=Cu, Co, Ni; L=ditopic rigid organic ligand) where all structural units (metal cations, chiral ligands and bridging ligands) could be changed with retention of the topology in the resulting framework. Compound 3 has a different structure and contributes to a different family of isoreticular homochiral MOFs.
Park, Seung-Keun,Kim, Jin Koo,Kim, Jong Hwa,Kang, Yun Chan Elsevier 2017 Materials characterization Vol.132 No.-
<P><B>Abstract</B></P> <P>Hollow Co<SUB>3</SUB>O<SUB>4</SUB> nanosphere aggregate/N-doped graphitic carbon (HCO/NGC) composite powders, exhibiting excellent Li-ion storage performances, were prepared by applying metal–organic frameworks (MOFs). Zeolitic imidazolate framework (ZIF)-67 cubes were reduced to produce Co/NGC composite powders. The Co/NGC composite powders were oxidized to produce cubic HCO/NGC composite powders, in which the hollow Co<SUB>3</SUB>O<SUB>4</SUB> nanospheres were uniformly covered with a NGC layer. The Co nanocrystals transformed into hollow nanospheres during oxidation via the nanoscale Kirkendall diffusion process. The unique composite structure accommodates mechanical stress owing to the void spaces within the Co<SUB>3</SUB>O<SUB>4</SUB> nanospheres; it also prevents structure collapse during cycling owing to the presence of the NGC matrix. Thus, the cubic hollow powders exhibited excellent electrochemical performances when used as an anode material in Li-ion batteries (LIBs). Following 250cycles, the HCO/NGC composite powders with 11wt% NGC delivered a discharge capacity of 1030mAhg<SUP>−1</SUP> at a current density of 1Ag<SUP>−1</SUP>. In addition, the composite powders delivered a discharge capacity of 738mAhg<SUP>−1</SUP> even at a high current density of 10Ag<SUP>−1</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aggregate of Co<SUB>3</SUB>O<SUB>4</SUB> hollow nanospheres was prepared by applying metal–organic frameworks. </LI> <LI> Kirkendall diffusion resulted in the formation of empty nanovoids within the Co<SUB>3</SUB>O<SUB>4</SUB> nanospheres. </LI> <LI> Aggregate of Co<SUB>3</SUB>O<SUB>4</SUB> hollow nanospheres exhibited excellent Li-ion storage performances. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>
Park, Seung-Keun,Yang, Su Hyun,Kang, Yun Chan Elsevier 2018 Chemical Engineering Journal Vol.349 No.-
<P><B>Abstract</B></P> <P>We report three-dimensional (3D) porous microspheres comprising interconnected carbon nanotubes (CNT) decorated with hollow NiCo<SUB>2</SUB>O<SUB>4</SUB> polyhedrons (H-NCO/CNT) for high-performance lithium-ion batteries (LIBs). The rationally designed composites are successfully fabricated via the combination of spray-pyrolysis and solution-based methods. The macroporous CNT microsphere obtained by spray pyrolysis acts as a substrate for the growth of the zeolitic imidazolate framework-67 (ZIF-67) in ethanol solution. During ion exchange and subsequent oxidation processes, the ZIF-67 polyhedrons were converted into hollow NiCo<SUB>2</SUB>O<SUB>4</SUB> polyhedrons consisting of small crystal domains. Rational design of such composite microspheres offers a highly conductive 3D porous network that simultaneously enables fast ion and electron diffusion deep inside the electrodes during cycling. In addition, the hollow polyhedron interiors can accommodate large volume changes and shorten the transport pathway for the ions and electrons. Owing to these structural advantages, high capacity, long cycle life, and excellent rate capability are achieved from H-NCO/CNT microspheres when applied as LIB anodes; the discharge capacity of H-NCO/CNT microspheres remained at 1673 mA h g<SUP>−1</SUP> after 200 cycles at a current density of 1.0 A g<SUP>−1</SUP>. Even when cycled at a high current density of 20.0 A g<SUP>−1</SUP>, a high capacity of 639 mA h g<SUP>−1</SUP> could be achieved.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CNT microspheres decorated with hollow NiCo<SUB>2</SUB>O<SUB>4</SUB> polyhedrons are facilely synthesized. </LI> <LI> ZIF-67 polyhedrons are converted into hollow NiCo<SUB>2</SUB>O<SUB>4</SUB> polyhedrons. </LI> <LI> Unique structured composite microspheres exhibit excellent lithium-ion storage properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Three-dimensional interconnected microspheres comprising CNTs decorated with hollow NiCo<SUB>2</SUB>O<SUB>4</SUB> polyhedrons were successfully synthesized via the combination of spray pyrolysis and solution-based methods. The unique features of composite microspheres such as the hollow interiors of polyhedrons and macroporous CNT backbones are beneficial for improved electrochemical performance when applied as LIB anodes. Thus, the electrode exhibited high capacity, long cycle life, and excellent rate capability as an anode material for LIBs.</P> <P>[DISPLAY OMISSION]</P>
Kim, Dongwon,Kim, Daekyu,Jeon, Youngmoo,Li, Yong,Lee, Jeongyeon,Kang, Jeongmin,Lee, Lawrence Yoon Suk,Piao, Yuanzhe Elsevier 2019 ELECTROCHIMICA ACTA Vol.299 No.-
<P><B>Abstract</B></P> <P>The development of highly effective and low-cost non-noble metal electrochemical catalysts for oxygen evolution reactions (OER) is a major challenge for overall water splitting and rechargeable metal-air batteries. In this study, we develop a novel hollow cobalt-borate modified cobalt oxide composite (denoted by Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB>) catalyst derived from zeolitic imidazolate framework-67 (ZIF-67) for electrochemical OER. The Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was easily synthesized via pyrolysis of ZIF-67 in Ar and air to produce hollow Co<SUB>3</SUB>O<SUB>4</SUB> (denoted by h-Co<SUB>3</SUB>O<SUB>4</SUB>), followed by simple NaBH<SUB>4</SUB> treatment at ambient temperature for 4 h. The unique polyhedral morphology was well preserved during the NaBH<SUB>4</SUB> treatment. Benefiting from its structural and compositional merit, the as-synthesized Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> exhibit excellent electrocatalytic activity and long-term stability for OER. Also, we conducted the OER test using a Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> catalyst in a neutral pH environment for further investigation. Our study can provide an insight into catalyst modification step to enhance the overall performance while keeping its physical structure simultaneously. using metal-organic framework for the electrochemical catalyst thus can be recognized as a method for producing a highly active, long-term working and novel engineered electrocatalyst for OER applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was prepared using calcination-NaBH<SUB>4</SUB> treatment strategy with a facile and energy efficient method. </LI> <LI> A distinctive polyhedral morphology of Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was well preserved after the NaBH<SUB>4</SUB> treatment of its precursor material. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was employed for the electrochemical oxygen evolution reaction. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> showed excellent catalytic performance and long-term durability for oxygen evolution reaction in basic media. </LI> </UL> </P>
Soundharrajan, Vaiyapuri,Sambandam, Balaji,Song, Jinju,Kim, Sungjin,Jo, Jeonggeun,Duong, Pham Tung,Kim, Seokhun,Mathew, Vinod,Kim, Jaekook Academic Press 2017 Journal of Colloid and Interface Science Vol. No.
<P><B>Abstract</B></P> <P>In the present study, a metal-organic framework (MOF) derived from a facile water-assisted green precipitation technique is employed to synthesize phase-pure cobalt vanadate (Co<SUB>3</SUB>V<SUB>2</SUB>O<SUB>8</SUB>, CVO) anode for lithium-ion battery (LIB) application. The material obtained by this eco-friendly method is systematically characterized using various techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N<SUB>2</SUB> adsorption–desorption measurements. By using as an anode, an initial discharge capacity of 1640mAhg<SUP>−1</SUP> and a reversible capacity of 1194mAhg<SUP>−1</SUP> are obtained at the applied current densities after the 240th cycle (2Ag<SUP>−1</SUP> for 200 cycles followed by 0.2Ag<SUP>−1</SUP> for 40 cycles). Moreover, a reversible capacity as high as 962mAhg<SUP>−1</SUP> is retained at high current densities even after 240 cycles (4Ag<SUP>−1</SUP> for 200 cycles followed by 2Ag<SUP>−1</SUP> for 40 cycles), revealing the long life stability of the electrode. Significantly, CVO anode composed of fine nanoparticles (NPs) registered a substantial rate performance and reversible specific capacities of 275, 390, 543 and 699mAhg<SUP>−1</SUP> at high reversibly altered current densities of 10, 5, 2, and 1Ag<SUP>−1</SUP>, respectively.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>