The African Maize Cobs (AMC) biomass was converted into activated carbon (AC) for electrode mater... more The African Maize Cobs (AMC) biomass was converted into activated carbon (AC) for electrode materials for supercapacitor application. The carbonization was carried out with concentrated sulphuric acid and the activation was done in three (3) batches using activation temperatures of 600, 700 and 800oC. The AC materials were characterized by Thermogravimetric analysis (TGA-DSC), N2-adsorption-desorption isotherms, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Boehm titration, X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy and electrochemical analysis (EC). The materials activated were highly functionalized with oxygen groups with total acidity of 0.440 – 0.464mmol/g, basicity of 0.09 – 0.420mmol/g and oxygen percentage composition of 22 – 32%. The AC materials were analysed with EC as electrode material for supercapacitor devices. The electrode materials revealed specific capacitance of; 456.4 ...
Abstract An adaptable and simplified arc underwater set-up is designed for synthesis of nanostruc... more Abstract An adaptable and simplified arc underwater set-up is designed for synthesis of nanostructured carbon materials (NSCM) such as carbon onions (CO), multi-walled carbon nanotubes (MWCNTs) and nanoscale graphitic carbon (NGC). Essentially, the set-up consists of a DC power supply, two graphite electrodes and a container for de-ionized water storage. Transmission electron microscopic analysis confirmed that the cathode deposit, floating particles and settled materials consist of MWCNTs, CO and NGC, respectively. The kind of NSCM formation is critically governed by temperature gradient and cooling rate created due to bubble collapse in nucleate boiling during the arcing process. Based on the anode consumption, the total yield of the carbon materials is about ∼ 25.5 wt% which consists 5 wt% of FP, 8.5 wt% of CD and remaining 12 wt% of SP. FP, CD, and SP presented crystallite size of 23.69 nm, 11.84 nm, and 28.91 nm, respectively. The high rate and moderate rate of cooling will determine the growth of MWCNTs and CO, respectively. NGC exhibited specific capacity of 325 mAhg − 1 with lithium half-cell after 50 cycles at a current density of 100 mAg−1.
Natural graphite flakes were intercalated with strong oxidizing agents and were converted into th... more Natural graphite flakes were intercalated with strong oxidizing agents and were converted into thermally expanded graphite (TEG) through thermal exfoliation. Thermally expanded graphite was delaminated and transformed into graphene nanoplatelets (GNP) by using ultrasonic irradiation. GNP integrated polyaniline (PANi) nanocomposites were synthesized via in-situ polymerization of aniline monomers in the presence of GNP. The structure and morphology of composite was evidenced by scanning electron microscopy, Transmission electron microscopy (TEM), X-ray diffraction and Raman spectroscopy. TEM micrographs revealed that GNP consists of 20–25 graphene layers and PANi was uniformly coated on GNP. From Raman analysis it was showed significant interactions between GNP and polyaniline. Electrical conductivity was measured by using 4-point probe device, enhanced conductivity was obtained for composite.
Graphene nanoplatelets (GNP) with few layers were prepared via expanded graphite derived from exf... more Graphene nanoplatelets (GNP) with few layers were prepared via expanded graphite derived from exfoliation and, then solution-phase exfoliation. GNPs consist of 7–12 distinguishable graphene layers and possess lateral sizes in the range of 2–6 μ. An attempt was made to exploit the thermal properties of GNP as filler to ameliorate thermo physical properties of xylitol. Such ultrathin 2-D structured GNP could able to increase thermal conductivity by 38% with the addition of low concentration associated with a reasonable enthalpy of fusion. Phase change materials find application in a medium temperature range such as thermal energy storage of solar energy, direct contact heat storage in heat exchangers, thermal energy storage in spacecraft systems, cooling of engines and compact electronic appliances.
We report on a simplistic procedure of converting solid waste (discarded bicycle’s rubber tube) t... more We report on a simplistic procedure of converting solid waste (discarded bicycle’s rubber tube) to value-added low-dimensional carbon material, and it was used as a negative material (anode) for Na...
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021
Abstract We report on capacitive properties of functionally-graded porous activated nanoscaled-gr... more Abstract We report on capacitive properties of functionally-graded porous activated nanoscaled-graphene platelets (aNGNS) prepared via reexfoliation of graphite, and high-energy fragmentation through mixed solvent strategy followed by thermochemical etch-away conversion. aNGNS based symmetric supercapacitor demonstrated excellent specific capacitance of 242 F/g at the current density of 0.5A/g with a capacity retention of 97.21 % after 1000 cycles. The device shown remarkable energy density of 27.22 Wh/kg at a power density of 230.56 W/kg at constant current density of 0.5 A/g. Moreover, the enormous amount of porosity created via chemical-assisted etching could facilitate minimal ion-diffusion resistance to achieve exceptional specific capacitance.
Oxidation behavior of tungsten disulphide (WS2) nanosheet powder with an average thickness of abo... more Oxidation behavior of tungsten disulphide (WS2) nanosheet powder with an average thickness of about 10 nm was studied in the temperature range of 25-700°C. The samples were subjected to exposures...
Abstract Among various energy storage devices, pseudo capacitive supercapacitors have gained much... more Abstract Among various energy storage devices, pseudo capacitive supercapacitors have gained much attention due to its unique features of high-power density and fair enough energy density. This work is aimed to fabricate high power density and energy density supercapacitor by using MnO2 nano-flakes as electrode material. MnO2 nano-flakes have been synthesized using hydrothermal technique and incorporated in supercapacitor structure to study the performance. The electrochemical performance of MnO2 nano-flake electrode was investigated and obtained a specific capacitance of 145 F.g−1 at 5 mV.s−1 with energy density of 20.16 Wh.kg−1 and power density of 363.03 W.kg−1.
Abstract For sustainable application of supercapacitor high energy density along with high power ... more Abstract For sustainable application of supercapacitor high energy density along with high power density is becoming an obvious requirement. This work is aimed at utilizing the features of 2D-layered structure and high surface area of MoS2 as electrode for supercapacitor to achieve high energy density and capacitance retention. One step hydrothermal technique is used to synthesize MoS2 layered structure and its performance is studied through electrochemical analysis. The electrochemical performance of MoS2 electrode is tested in a full cell module and a specific capacitance of 255 F·g−1 at 0.25 A·g−1 with energy density of 35.5 W·kg−1 is achieved.
ABSTRACT Substitutional nitrogen doped aligned carbon nanotubes (NACNTs) with uniform height and ... more ABSTRACT Substitutional nitrogen doped aligned carbon nanotubes (NACNTs) with uniform height and high packing density of arrays was synthesized by using the liquid injection CVD process. Transmission electron micrographs indicated that the NACNTs are having nano-bell morphology of graphene layers with series of internal compartments. Field emission study of NACNTs showed that they are good emitters with low turn-on and threshold field. The maximum current density was observed to be 18.8 mA/cm2 at electric field of 1.89 V/μm.
... these results. We are also thankful to Dr. Padmanabham, Associate Director for his encour-age... more ... these results. We are also thankful to Dr. Padmanabham, Associate Director for his encour-agement during this work. We also thank Ms. Malathi, Mr. G. VenkatReddy and K. Subba Rao for their extensive help. The authors ...
The African Maize Cobs (AMC) biomass was converted into activated carbon (AC) for electrode mater... more The African Maize Cobs (AMC) biomass was converted into activated carbon (AC) for electrode materials for supercapacitor application. The carbonization was carried out with concentrated sulphuric acid and the activation was done in three (3) batches using activation temperatures of 600, 700 and 800oC. The AC materials were characterized by Thermogravimetric analysis (TGA-DSC), N2-adsorption-desorption isotherms, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Boehm titration, X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy and electrochemical analysis (EC). The materials activated were highly functionalized with oxygen groups with total acidity of 0.440 – 0.464mmol/g, basicity of 0.09 – 0.420mmol/g and oxygen percentage composition of 22 – 32%. The AC materials were analysed with EC as electrode material for supercapacitor devices. The electrode materials revealed specific capacitance of; 456.4 ...
Abstract An adaptable and simplified arc underwater set-up is designed for synthesis of nanostruc... more Abstract An adaptable and simplified arc underwater set-up is designed for synthesis of nanostructured carbon materials (NSCM) such as carbon onions (CO), multi-walled carbon nanotubes (MWCNTs) and nanoscale graphitic carbon (NGC). Essentially, the set-up consists of a DC power supply, two graphite electrodes and a container for de-ionized water storage. Transmission electron microscopic analysis confirmed that the cathode deposit, floating particles and settled materials consist of MWCNTs, CO and NGC, respectively. The kind of NSCM formation is critically governed by temperature gradient and cooling rate created due to bubble collapse in nucleate boiling during the arcing process. Based on the anode consumption, the total yield of the carbon materials is about ∼ 25.5 wt% which consists 5 wt% of FP, 8.5 wt% of CD and remaining 12 wt% of SP. FP, CD, and SP presented crystallite size of 23.69 nm, 11.84 nm, and 28.91 nm, respectively. The high rate and moderate rate of cooling will determine the growth of MWCNTs and CO, respectively. NGC exhibited specific capacity of 325 mAhg − 1 with lithium half-cell after 50 cycles at a current density of 100 mAg−1.
Natural graphite flakes were intercalated with strong oxidizing agents and were converted into th... more Natural graphite flakes were intercalated with strong oxidizing agents and were converted into thermally expanded graphite (TEG) through thermal exfoliation. Thermally expanded graphite was delaminated and transformed into graphene nanoplatelets (GNP) by using ultrasonic irradiation. GNP integrated polyaniline (PANi) nanocomposites were synthesized via in-situ polymerization of aniline monomers in the presence of GNP. The structure and morphology of composite was evidenced by scanning electron microscopy, Transmission electron microscopy (TEM), X-ray diffraction and Raman spectroscopy. TEM micrographs revealed that GNP consists of 20–25 graphene layers and PANi was uniformly coated on GNP. From Raman analysis it was showed significant interactions between GNP and polyaniline. Electrical conductivity was measured by using 4-point probe device, enhanced conductivity was obtained for composite.
Graphene nanoplatelets (GNP) with few layers were prepared via expanded graphite derived from exf... more Graphene nanoplatelets (GNP) with few layers were prepared via expanded graphite derived from exfoliation and, then solution-phase exfoliation. GNPs consist of 7–12 distinguishable graphene layers and possess lateral sizes in the range of 2–6 μ. An attempt was made to exploit the thermal properties of GNP as filler to ameliorate thermo physical properties of xylitol. Such ultrathin 2-D structured GNP could able to increase thermal conductivity by 38% with the addition of low concentration associated with a reasonable enthalpy of fusion. Phase change materials find application in a medium temperature range such as thermal energy storage of solar energy, direct contact heat storage in heat exchangers, thermal energy storage in spacecraft systems, cooling of engines and compact electronic appliances.
We report on a simplistic procedure of converting solid waste (discarded bicycle’s rubber tube) t... more We report on a simplistic procedure of converting solid waste (discarded bicycle’s rubber tube) to value-added low-dimensional carbon material, and it was used as a negative material (anode) for Na...
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021
Abstract We report on capacitive properties of functionally-graded porous activated nanoscaled-gr... more Abstract We report on capacitive properties of functionally-graded porous activated nanoscaled-graphene platelets (aNGNS) prepared via reexfoliation of graphite, and high-energy fragmentation through mixed solvent strategy followed by thermochemical etch-away conversion. aNGNS based symmetric supercapacitor demonstrated excellent specific capacitance of 242 F/g at the current density of 0.5A/g with a capacity retention of 97.21 % after 1000 cycles. The device shown remarkable energy density of 27.22 Wh/kg at a power density of 230.56 W/kg at constant current density of 0.5 A/g. Moreover, the enormous amount of porosity created via chemical-assisted etching could facilitate minimal ion-diffusion resistance to achieve exceptional specific capacitance.
Oxidation behavior of tungsten disulphide (WS2) nanosheet powder with an average thickness of abo... more Oxidation behavior of tungsten disulphide (WS2) nanosheet powder with an average thickness of about 10 nm was studied in the temperature range of 25-700°C. The samples were subjected to exposures...
Abstract Among various energy storage devices, pseudo capacitive supercapacitors have gained much... more Abstract Among various energy storage devices, pseudo capacitive supercapacitors have gained much attention due to its unique features of high-power density and fair enough energy density. This work is aimed to fabricate high power density and energy density supercapacitor by using MnO2 nano-flakes as electrode material. MnO2 nano-flakes have been synthesized using hydrothermal technique and incorporated in supercapacitor structure to study the performance. The electrochemical performance of MnO2 nano-flake electrode was investigated and obtained a specific capacitance of 145 F.g−1 at 5 mV.s−1 with energy density of 20.16 Wh.kg−1 and power density of 363.03 W.kg−1.
Abstract For sustainable application of supercapacitor high energy density along with high power ... more Abstract For sustainable application of supercapacitor high energy density along with high power density is becoming an obvious requirement. This work is aimed at utilizing the features of 2D-layered structure and high surface area of MoS2 as electrode for supercapacitor to achieve high energy density and capacitance retention. One step hydrothermal technique is used to synthesize MoS2 layered structure and its performance is studied through electrochemical analysis. The electrochemical performance of MoS2 electrode is tested in a full cell module and a specific capacitance of 255 F·g−1 at 0.25 A·g−1 with energy density of 35.5 W·kg−1 is achieved.
ABSTRACT Substitutional nitrogen doped aligned carbon nanotubes (NACNTs) with uniform height and ... more ABSTRACT Substitutional nitrogen doped aligned carbon nanotubes (NACNTs) with uniform height and high packing density of arrays was synthesized by using the liquid injection CVD process. Transmission electron micrographs indicated that the NACNTs are having nano-bell morphology of graphene layers with series of internal compartments. Field emission study of NACNTs showed that they are good emitters with low turn-on and threshold field. The maximum current density was observed to be 18.8 mA/cm2 at electric field of 1.89 V/μm.
... these results. We are also thankful to Dr. Padmanabham, Associate Director for his encour-age... more ... these results. We are also thankful to Dr. Padmanabham, Associate Director for his encour-agement during this work. We also thank Ms. Malathi, Mr. G. VenkatReddy and K. Subba Rao for their extensive help. The authors ...
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