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Citric acid stabilized iron oxide nanoparticles for battery- type supercapacitor electrode
Seungil Park,C. Justin Raj,Ramu Manikandan,Byung Chul Kim,Kook Hyun Yu 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.2
We report the synthesis of citrate stabilized iron oxide (C-Fe3O4) spherical nanoparticles for supercapacitor electrodes. Thecitrate functional group present in the surface of the Fe3O4 nanoparticles effectively controls the morphology and the surfacearea of the nanostructures. The C-Fe3O4 electrodes exhibited a battery-like energy storage properties with a maximum specificcapacity of 146 Cg−1 (242 Fg−1) which is much higher than the specific capacity of citrate free Fe3O4 electrode (62 Cg−1; 112Fg−1). Moreover, the C-Fe3O4 electrode showed better cyclic stability (75%) than the citrate free Fe3O4 electrode (~35%) after1000 charge/discharge cycles.
Rapid hydrothermal synthesis of cobalt oxyhydroxide nanorods for supercapacitor applications
Justin Raj, C.,Kim, B.C.,Cho, W.J.,Park, S.,Jeong, H.T.,Yoo, K.,Yu, K.H. Elsevier Sequoia 2015 Journal of Electroanalytical Chemistry Vol.747 No.-
Cobalt oxyhydroxide (CoOOH) nanorods were synthesized by fast hydrothermal process for supercapacitor electrodes. The structural and morphological studies revealed the formation of CoOOH with hexagonal rhomb-centered crystal structure and excellent rod like morphology of ~5-10nm diameter. The electrochemical characterization was performed for both half cell and symmetric full cell configuration using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 3M KOH aqueous electrolyte. The fabricated CoOOH electrodes showed maximum specific capacitance value of 198Fg<SUP>-1</SUP> for a half cell and 94Fg<SUP>-1</SUP> for a symmetric capacitor of 10mgcm<SUP>-2</SUP> active material per electrode and showed better energy and power densities. Moreover, the CoOOH electrode exhibits good capacitance retention (83%) after 5000 charge/discharge cycles.
Banyan Root Structured Mg-Doped ZnO Photoanode Dye-Sensitized Solar Cells
Raj, C. Justin,Prabakar, Kandasamy,Karthick, S. N.,Hemalatha, K. V.,Son, Min-Kyu,Kim, Hee-Je American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.6
<P>We report a peculiar banyan root like Mg-doped ZnO photoanode to result in high electron transport, retardation of interfacial charge recombination, improved light harvesting efficiency, and overall enhanced photovoltaic performance of dye-sensitized solar cells (DSSC). DSSC based on a 5 mol % Mg-doped ZnO electrode of very low thickness, ∼4 μm, gained an improved short-circuit current density of 9.98 mAcm<SUP>–2</SUP>, open-circuit photo voltage of 0.71 V, fill factor of 0.58, and overall conversion efficiency of 4.11% under 1 sun illumination.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-6/jp308847g/production/images/medium/jp-2012-08847g_0011.gif'></P>
Raj, C. Justin,Rajesh, Murugesan,Manikandan, Ramu,Yu, Kook Hyun,Anusha, J.R.,Ahn, Jun Hwan,Kim, Dong-Won,Park, Sang Yeup,Kim, Byung Chul Elsevier 2018 Journal of Power Sources Vol.386 No.-
<P><B>Abstract</B></P> <P>Activated carbon containing nitrogen functionalities exhibits excellent electrochemical property which is more interesting for several renewable energy storage and catalytic applications. Here, we report the synthesis of microporous oxygen and nitrogen doped activated carbon utilizing chitin from the gladius of squid fish. The activated carbon has large surface area of 1129 m<SUP>2</SUP> g<SUP>−1</SUP> with microporous network and possess ∼4.04% of nitrogen content in the form of pyridinic/pyrrolic-N, graphitic-N and N-oxide groups along with oxygen and carbon species. The microporous oxygen/nitrogen doped activated carbon is utilize for the fabrication of aqueous and flexible supercapacitor electrodes, which presents excellent electrochemical performance with maximum specific capacitance of 204 Fg<SUP>−1</SUP> in 1 M H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte and 197 Fg<SUP>−1</SUP> as a flexible supercapacitor. Moreover, the device displays 100% of specific capacitance retention after 25,000 subsequent charge/discharge cycles in 1 M H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel O- and N- doped activated carbon is derived from squid gladius chitin. </LI> <LI> The microporous carbon is used for the fabrication of supercapacitor electrodes. </LI> <LI> The supercapacitors demonstrated remarkable electrochemical performances. </LI> <LI> The device shows long stability of ∼100% after 25,000 charge/discharge cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Manikandan, Ramu,Raj, C. Justin,Nagaraju, Goli,Pyo, Myoungho,Kim, Byung Chul The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.44
<P>Recently, binder-free and hierarchical electrode materials have attracted special attention for the rational design of high-energy density hybrid supercapacitors. Herein, we demonstrated binder-free nickel molybdenum sulfide nano-flakes on nickel foam (NMS-Ni) using a facile successive ionic layer adsorption and reaction (SILAR) process for the fabrication of high-performance hybrid supercapacitors. The selective SILAR cycles had a significant effect on the morphology and electrochemical properties of the NMS nanostructures. Specifically, the NMS deposited for 40 cycles (40cyc@NMS-Ni) displayed the maximum areal capacity (<I>C</I>Ac) of 2.8 C cm<SUP>−2</SUP> (2224 C g<SUP>−1</SUP>) at the current density 4 mA cm<SUP>−2</SUP> in a 6 M KOH electrolyte. Furthermore, a hybrid supercapacitor (HSC) was fabricated using 40cyc@NMS-Ni as the positive electrode and N,O-enriched activated carbon (N,O-AC)-coated Ni-foam as the negative electrode, which showed the maximum potential and specific capacitance (<I>C</I>F-cell) of 1.5 V and 111 F g<SUP>−1</SUP>, respectively. Moreover, the device displayed an outstanding specific energy and specific power of 35 W h kg<SUP>−1</SUP> and 1.5 kW kg<SUP>−1</SUP> with an excellent capacitance retention (95%) after 5000 cycles, respectively. Thus, based on the observed results, it can be concluded that the present study demonstrates a route to utilize NMS-based electrodes as a promising material for high-performance energy storage devices.</P>
Structural and electrochemical characterization of proton beam irradiated manganese dioxide
이원길,( C. Justin Raj ),유국현 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Among various pseudo capacitive materials, manganese dioxide (MnO2) is a promising electrode material because of its high theoretical specific capacitance, abundant resources, low-cost, and eco-friendliness. But the poor conductivity and less electron transport properties of MnO2 limited their practical applications. The high power proton irradiation can effectively modify the electronic properties and surface states of the materials, also the irradiation can caused defects in the materials. Impurities in a crystal constitute structural imperfections which can alter electrical and mechanical properties of the materials. Moreover the irradiation creates secondary-electron charge carriers, and thus affects electrical properties of the materials, even it can improve the conductivity of the materials. We researched about electronic properties of the proton irradiated MnO2 by fabricating electrodes for super capacitor and checked the modifications of MnO2 nanostructure.
심주용,C. Justin Raj,유국현 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.7
The biodegradable poly(butylene adipate-co-terephthalate) (PBAT) polymer was synthesized via one pot synthesis technique using adipic acid and butanediol. The polymerization of synthesized sample was confirmed using FTIR, NMR, and TGA analysis. The PBAT/ATO films were fabricated via spray coating technique utilizing various concentrations of ATO nanoparticles in PBAT polymer solution and optimized the film quality through optical (NIR) and surface analysis. The polymer film having 7 wt % of ATO in PBAT showed good transparency in the UV, visible light and shown approximately 41% absorption in the near infrared region. Moreover, the 7 wt % ATO based polymer film exhibited low surface roughness and uniform coating over the substrate. In addition, near infrared absorbing efficiency of PBAT/ATO composite film in outdoor was demonstrated by constructing a PBAT/ATO (7 wt %)/vinyl greenhouse and the temperature differences were comparatively studied with a bare vinyl green house.