Porous 3D-b-nickel hydroxide microflowers for electrochemical supercapacitors

SINGUBALSYDULU,윤국로 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

In this work we have carried out synthesis of porous three dimensional nickel hydroxide (3D-b-Ni(OH)2)microflowers by chemical bath deposition. The structure of the porous 3D-b-Ni(OH)2 microflowerscharacterized by using FT-IR, TGA, XRD, FE-SEM, TEM and XPS. The specific capacitance of the porous 3Db-Ni(OH)2 microflowers were showing around 249 F/g from cyclic voltammetry. The discharge specificcapacitance of the porous 3D-b-Ni(OH)2 microflowers were found to be 170 and 245 F/g for the 1st and8000th cycles, respectively. The energy and power density of the porous 3D-b-Ni(OH)2 microflowersfound to be 8.5 W h/kg and 2497.9 W/kg, respectively at the discharge current density of 0.05 A/g.

Preparation and performance of polyaniline–multiwall carbon nanotubes–titanium dioxide ternary composite electrode material for supercapacitors

SINGUBALSYDULU,Umashankar Male,Palaniappan Srinivasan,윤국로 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.49 No.-

Multi-walled carbon nanotubes (MWNTs), and titanium oxide (TiO2) were incorporated in polyaniline(PANI) to enhance the pseudocapacitance and cycle stability of PANI. PANI–MWNTs–TiO2, ternarycomposite was prepared by in-situ chemical polymerization of aniline in the presence of MWNTs andTiO2. Morphology analysis of ternary composite revealed the uniform covering of MWNTs by PANInanofibers and TiO2 nanoparticles. The specific capacitance of PANI–MWNTs–TiO2 is 270 F g 1, muchhigher than that of MWNTs (30 F g 1) and PANI (210 F g 1) electrodes. PANI–MWNTs–TiO2 showed goodrate capability with excellent cycling stability.

Sulfur-doped nickel oxide spherical nanosheets for redox supercapacitors

SINGUBALSYDULU,홍상은,윤국로 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.62 No.-

We have synthesized sulfur-doped nickel oxide (S-NiO) spherical nanosheets by emulsion method. The structure of the S-NiO nanosheets is characterized by using TGA, XRD, XPS, BET, FE-SEM and FE-TEM. From the TGA, XPS and EDAX results conclude the nickel oxide is doped with sulfur. The specific capacitance of the S-NiO nanosheets was showing 313 F g−1 at the sweep rate of 5 mV s−1 by cyclic voltammetry. The S-NiO nanosheets showing the high rate performance of 80% at the current density ranging from 1 to 8 A g−1 and high retention of the capacitance 99% after completion of 1000 charge–discharge cycles.

Carbon Nanotube–Manganese oxide nanorods hybrid composites for high-performance supercapacitor materials

SINGUBALSYDULU,Emad S. Goda,윤국로 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.97 No.-

In the present work, multiwall carbon nanotubes (CNTs) were used as a reducing agent for thepreparation of CNT-MnO2 nanocomposites by varying the amount of potassium permanganate (KMnO4). The chemical compositions of the as-synthesized materials were analyzed using X-ray diffraction,Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, which showed theformation of MnO2 in the CNT-MnO2 nanocomposites. The electrochemical properties of the CNT-MnO2nanocomposites were thoroughly investigated through cyclic voltammetry, charge–discharge, andimpedance studies. The CNT-MnO2-25 nanocomposites appeared with the highest specific capacitance of674 F g 1 at a current density of 2 A g 1; they also displayed an excellent capacitance retention of110%even after the completion of 5000 continuous charge–discharge cycles at 10 A g 1.

Sulfur-doped nickel oxide spherical nanosheets for redox supercapacitors

Singu, Bal Sydulu,Hong, Sang Eun,Yoon, Kuk Ro THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.62 No.-

<P><B>Abstract</B></P> <P>We have synthesized sulfur-doped nickel oxide (S-NiO) spherical nanosheets by emulsion method. The structure of the S-NiO nanosheets is characterized by using TGA, XRD, XPS, BET, FE-SEM and FE-TEM. From the TGA, XPS and EDAX results conclude the nickel oxide is doped with sulfur. The specific capacitance of the S-NiO nanosheets was showing 313Fg<SUP>−1</SUP> at the sweep rate of 5mVs<SUP>−1</SUP> by cyclic voltammetry. The S-NiO nanosheets showing the high rate performance of 80% at the current density ranging from 1 to 8Ag<SUP>−1</SUP> and high retention of the capacitance 99% after completion of 1000 charge–discharge cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of sulfur-doped nickel oxide spherical nanosheets with the thickness of <10nm. </LI> <LI> As prepared nickel hydroxide present in the form of nanodiscs. </LI> <LI> S-NiO exhibiting high capacitance of 313Fg<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis and characterization of MnO₂-decorated graphene for supercapacitors

Singu, Bal Sydulu,Yoon, Kuk Ro Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>We report the simple one-step synthesis of a reduced graphene oxide–manganese oxide (rGO-MnO<SUB>2</SUB>) nanocomposite using graphene oxide (GO) and KMnO<SUB>4</SUB> in the presence of sulfuric acid. The crystal structure, morphology, thermal, pore size, and other physical properties of the rGO-MnO<SUB>2</SUB> nanocomposite were systematically analyzed by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller analysis. XPS analysis confirmed the synthesis of exfoliated GO and rGO-MnO<SUB>2</SUB> nanocomposite. The rGO-MnO<SUB>2</SUB> nanocomposite exhibited a maximum specific capacitance, energy, and power density of 290Fg<SUP>−1</SUP>, 25.7Whkg<SUP>−1</SUP>, and 8008.7Wkg<SUP>−1</SUP>, respectively, in a 1M Na<SUB>2</SUB>SO<SUB>4</SUB> electrolyte, and a high retention (87.5%) of capacitance after 5000 cycles. The enhanced electrochemical properties are caused by good contact between MnO<SUB>2</SUB> nanorods and graphene nanosheets, and the higher conductive and capacitive behavior of graphene.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Exfoliated graphene-manganese oxide nanocomposite electrode materials for supercapacitor

Singu, Bal Sydulu,Yoon, Kuk Ro Elsevier 2019 Journal of alloys and compounds Vol.770 No.-

<P><B>Abstract</B></P> <P>In this paper, one-pot approach was used to produce the highly exfoliated reduced graphene oxide-manganese oxide nanocomposites (rGO-MnO<SUB>x</SUB> and rGO-Mn<SUB>3</SUB>O<SUB>4</SUB>) and systematically analyzed by spectral, thermal, elemental and electron microscope. From the FE-SEM analysis confirms the exfoliated reduced graphene oxide-manganese oxide nanocomposites formation. In the nanocomposites, manganese oxide nanoparticles present in the spherical (rGO-Mn<SUB>3</SUB>O<SUB>4</SUB>), spherical and cube shape (rGO-MnO<SUB>x</SUB>). The electrochemical properties of the rGO-MnO<SUB>x</SUB> and rGO-Mn<SUB>3</SUB>O<SUB>4</SUB> nanocomposites were analyzed by cyclic voltammetry and charge-discharge study. The highly exfoliated rGO-MnO<SUB>x</SUB> nanocomposite show the higher electrochemical capacitive responsive than rGO-Mn<SUB>3</SUB>O<SUB>4</SUB> nanocomposite. The rGO-MnO<SUB>x</SUB> nanocomposite exhibiting the utmost capacitance of 398.8 F g<SUP>−1</SUP> at a sweep rate of 5 mV s<SUP>−1</SUP>, the energy density of 23.3 Wh kg<SUP>−1</SUP> and power density of 2001 W kg<SUP>−1</SUP>, owing to the synergistic effect of reduced graphene oxide and spherical and cubical shape of manganese oxide nanoparticles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Exfoliated reduced graphene oxide-manganese oxide nanocomposites are prepared. </LI> <LI> The rGO-MnO<SUB>x</SUB> nanocomposite exhibiting the utmost capacitance of 398.8 F g<SUP>−1</SUP>. </LI> <LI> The rGO-MnO<SUB>x</SUB> has showing the capacitance retention of 80% over 5000 cycles. </LI> </UL> </P>

Honeycomb-like manganese oxide nanospheres for redox supercapacitors

Singu, Bal Sydulu,Hong, Sang Eun,Yoon, Kuk Ro INSTITUTE FOR IONICS 2018 IONICS -KIEL- Vol.24 No.2

<P>Honeycomb-like MnO2 nanospheres were synthesized using stainless steel substrates by a facile chemical bath deposition method. The obtained nanospheres were about 200-400 nm in diameter and consisted of porous ultrathin nanosheets. Honeycomb-like MnO2 nanospheres exhibited a high specific capacitance of 240 F g(-1) and 87.1% capacitance retention after 1000 cycles at a current density of 0.5 A g(-1). These remarkable electrochemical results imply great potential for applications of the honeycomb-like MnO2 nanospheres in supercapacitors.</P>

Ultra-thin and ultra-long α-MnO2 nanowires for pseudocapacitor material

Singu, Bal Sydulu,Hong, Sang Eun,Yoon, Kuk Ro Springer-Verlag 2017 Journal of solid state electrochemistry Vol.21 No.11

Highly exfoliated GO-PPy-Ag ternary nanocomposite for electrochemical supercapacitor

Singu, Bal Sydulu,Yoon, Kuk Ro Elsevier 2018 ELECTROCHIMICA ACTA Vol.268 No.-

<P><B>Abstract</B></P> <P>In this work, we report the one-pot synthesis of highly exfoliated graphene oxide-polypyrrole-Ag (GO-PPy-Ag) ternary nanocomposite using graphene oxide, silver nitrate and pyrrole. Formation of highly exfoliated GO-PPy-Ag ternary nanocomposite was systematically investigated by using FT-IR, Raman, XRD, XPS, TGA, BET, FE-SEM and TEM. Based on the surface morphology, it is concluded that the PPy-Ag nanoparticles are uniformly distributed over the highly exfoliated graphene oxide nanosheets. From the electrochemical study, GO-PPy-Ag ternary nanocomposite exhibits a highest specific capacitance of 370.6 F g<SUP>−1</SUP> than the corresponding PPy-Ag binary nanocomposite (103.4 F g<SUP>−1</SUP>). The GO-PPy-Ag ternary nanocomposite showing the high rate performance of 87.4% at a current density ranging from 1 to 10 A g<SUP>−1</SUP>. The improved electrochemical properties are attributed to the good contact between PPy-Ag nanoparticles and graphene oxide nanosheets.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>