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Ramchandra Pode,안정선,Woo Sik Jeon,Tae Jin Park,권장혁 한국물리학회 2009 Current Applied Physics Vol.9 No.5
Highly efficient red phosphorescent devices comprising a simple bi-layered structure using tris(1-phenylisoquinoline)iridium (Ir(piq)3) doped in a narrow band-gap fluorescent host material, bis(10-hydroxy-benzo [h] quinolinato)beryllium complex (Bebq2) are reported. The driving voltage to reach 1000 cd/㎡ is 3.5 V in Bebq2:Ir(piq)3 red phosphorescent device. With a dopant concentration of as low as 4%, the current and power efficiency values of 8.41 cd/A and 7.34 lm/W are obtained in this PHOLEDs, respectively. External quantum efficiency (EQE) of 14.5% is noticed in this red phosphorescent device, promising to high brightness applications.
Ceria based catalyst for cathode in non-aqueous electrolyte based Li/O<sub>2</sub> batteries
Kalubarme, Ramchandra S,Cho, Min-Seung,Kim, Jae-Kook,Park, Chan-Jin IOP Pub 2012 Nanotechnology Vol.23 No.43
<P>This study suggests combustion synthesized Ce<SUB>1−x</SUB>Zr<SUB>x</SUB>O<SUB>2</SUB> (CZO; x = 0.1–0.5) as a new catalyst for the cathode in non-aqueous electrolyte based Li/O<SUB>2</SUB> cells. The spherical catalysts have a fluorite structure with a mean diameter of 5–17 nm. Zr doping into the ceria lattice leads to the reduction of Ce<SUP>4+</SUP> to Ce<SUP>3+</SUP>, which further improves the catalyst performance. Electrochemical studies of CZO as a cathode catalyst in the Li/O<SUB>2</SUB> cell show that CZO follows a two-electron pathway for oxygen reduction. A maximum discharge capacity of 1620 mAh g<SUP>−1</SUP> is obtained for the Ce<SUB>0.8</SUB>Zr<SUB>0.2</SUB>O<SUB>2</SUB> catalyst due to its high surface area and porosity. A composite of CZO and MnO<SUB>2</SUB> shows even better performance as a cathode catalyst for the Li/O<SUB>2</SUB> cell. </P>
Kalubarme, Ramchandra S,Kim, Yong-Han,Park, Chan-Jin IOP Pub 2013 Nanotechnology Vol.24 No.36
<P>A carbon nanotube (CNT)/cerium oxide composite was prepared by a one-pot hydrothermal reaction in the presence of KOH and capping agent polyvinylpyrrolidone. The nanocomposite displayed pronounced capacitive behaviour with very small diffusion resistance. The electrochemical performance of the composite electrode in a symmetric supercapacitor displayed a high energy density of 35.9 Wh kg<SUP>−1</SUP> corresponding to a specific capacitance of 289 F g<SUP>−1</SUP>. These composite electrodes also demonstrated a long cycle life with better capacity retention.</P>
Pode, Ramchandra,Ahn, Jeung-Sun,Jeon, Woo Sik,Park, Tae Jin,Kwon, Jang Hyuk Elsevier 2009 CURRENT APPLIED PHYSICS Vol.9 No.5
<P><B>Abstract</B></P><P>Highly efficient red phosphorescent devices comprising a simple bi-layered structure using tris(1-phenylisoquinoline)iridium (Ir(piq)<SUB>3</SUB>) doped in a narrow band-gap fluorescent host material, bis(10-hydroxybenzo [h] quinolinato)beryllium complex (Bebq<SUB>2</SUB>) are reported. The driving voltage to reach 1000cd/m<SUP>2</SUP> is 3.5V in Bebq<SUB>2</SUB>:Ir(piq)<SUB>3</SUB> red phosphorescent device. With a dopant concentration of as low as 4%, the current and power efficiency values of 8.41cd/A and 7.34lm/W are obtained in this PHOLEDs, respectively. External quantum efficiency (EQE) of 14.5% is noticed in this red phosphorescent device, promising to high brightness applications.</P>
Kalubarme, Ramchandra S.,Lee, Jae-Young,Park, Chan-Jin American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.31
<P>The major obstacle in realizing sodium (Na)-ion batteries (NIBs) is the absence of suitable negative electrodes. This is because graphite, a commercially well known anode material for lithium-ion batteries, cannot be utilized as an insertion host for Na ions due to its large ionic size. In this study, a simple and cost-effective hydrothermal method to prepare carbon coated tin oxide (SnO<SUB>2</SUB>) nanostructures as an efficient anode material for NIBs was reported as a function of the solvent used. A single phase SnO<SUB>2</SUB> resulted for the ethanol solvent, while a blend of SnO and SnO<SUB>2</SUB> resulted for the DI water and ethylene glycol solvents. The elemental mapping in the transmission electron microscopy confirmed the presence of carbon coating on the SnO<SUB>2</SUB> nanoparticles. In cell tests, the anodes of carbon coated SnO<SUB>2</SUB> prepared in ethanol solvent exhibited stable cycling performance and attained a capacity of about 514 mAh g<SUP>–1</SUP> on the first charge. With the help of the conductive carbon coating, the SnO<SUB>2</SUB> delivers more capacity at high rates: 304 mAh g<SUP>–1</SUP> at the 1 C rate, 213 mAh g<SUP>–1</SUP> at the 2 C rate and 133 mAh g<SUP>–1</SUP> at the 5 C rate. The excellent cyclability and high rate capability are the result of the formation of a mixed conducting network and uniform carbon coating on the SnO<SUB>2</SUB> nanoparticles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-31/acsami.5b04178/production/images/medium/am-2015-04178y_0017.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b04178'>ACS Electronic Supporting Info</A></P>
Kalubarme, Ramchandra S.,Park, Ga-Eun,Jung, Kyu-Nam,Shin, Kyoung-Hee,Ryu, Won-Hee,Park, Chan-Jin The Electrochemical Society 2014 Journal of the Electrochemical Society Vol.161 No.6
<P>The oxygen electrode is a vital element in developing lithium-oxygen batteries, because it provides the active sites for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In addition, the performance of the oxygen electrode strongly depends on the activity and architecture of materials employed. Perovskite oxide nanostructures of nickel-doped lanthanum cobaltite were prepared by a very simple and cost-effective solution combustion synthesis. The oxygen electrode containing a carbon-supported perovskite oxide catalyst with oxygen vacancies exhibited reduced polarization and improved discharge capacity compared with that containing only bare carbon without a catalyst. In particular, the LaNi<SUB>0.25</SUB>Co<SUB>0.75</SUB>O<SUB>3-δ</SUB> catalyst showed the best catalytic activity for OER by achieving the oxidation of Li<SUB>2</SUB>O<SUB>2</SUB> at 3.8 V. The widespread dispersion and mesoporous design of perovskite facilitates the diffusion of electrolyte and oxygen into the inner electrode to demonstrate cyclability for 49 cycles while maintaining a moderate specific capacity of 1000 mAh g<SUP>−1</SUP>. Further, the synergistic effect of the fast kinetics of electron transport provided by the carbon support and the high electro-catalytic activity of the perovskite oxide resulted in excellent performance of the oxygen electrode for Li-O<SUB>2</SUB> batteries.</P>
Naik, Prafulla-Ramchandra,Singh, Girija-Shankar,Pandeya, Surendra-Nath,Singh, Paras-Nath The Pharmaceutical Society of Korea 1994 Archives of Pharmacal Research Vol.17 No.4
The titled compounds have been synthesized by the oxidative cyclization of N-ethyl-N'-aryl-thioureas and screened for their anti-inflammatory and analogesic activities. Some of the compounds exhibit significant activities.