Santosini Patra

We report a simple and low-cost technique to prepare a composite comprising of activated carbon and few layers of graphene sheets and fabricated as electrode material for supercapacitor (SC) applications. The composite is characterised by using Raman spectroscopy, powder X-ray diffraction (XRD), scanning electron microscope (SEM) and current-voltage (I-V) measurements. The synthesized composite is investigated by using galvanostatic chargedischarge (GCD) and cyclic voltammetry (CV) measurements in 3M KOH aqueous electrolyte to evaluate its electrochemical performance. The composite results high specific capacitance from 173 to 564 F/g at different scan rates (100-5 mV/s), analysed by CV and the capacitances resulted in GCD measurement were 196 to 587 F/g at various current densities (5-1 A/g). The cycle stability of the as-prepared AC/graphene composite is also tested and observed that 89% of capacitance is retained even after 5000 cycles which reveals the excellent long term charge...

We report the preparation of an electrode material made up of MnO2/graphene/ activated carbon ternary composite by hydrothermal method for supercapacitor (SC) applications. The prepared ternary composite has been characterized by using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman spectroscopy measurements. The prepared objective electrode has been investigated using galvanostatic charge-discharge (GCD) and cyclic voltammetry (CV) measurements in a 3-electrode system using 3M KOH aqueous electrolyte for the analysis of their electrochemical performance. The prepared MnO2 /graphene/activated carbon composite results in maximum capacitance of ∼493.57 F/g at 5 mV/s using CV and moreover the highest capacitance obtained from the GCD measurement is ∼485.29 F/g at 1 A/g. The long-term cycle stability of the composite electrode is also demonstrated and it shows outstanding cyclic performance where 97% of capacitance is le...

Abstract A composite has been prepared by incorporating few layers of graphene sheets (FLGS) synthesized by an electrochemical method in poly (3-hexylthiophene-2, 5-diyl) (P3HT): [6] , [6] -phenyl-C61-butyric acid methyl ester (PCBM). The composite has been used as active layer in the photovoltaic device (ITO/FLGS:P3HT:PCBM/Al) and the device characteristics were investigated. The as prepared FLGS has been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV–Vis), and Raman spectroscopy. The performance of the composite based device has been studied under illumination and the results have been compared with the reference device (ITO/P3HT:PCBM/Al). Short circuit current density (Jsc) of 6.24 mA.cm−2, open circuit voltage (Voc) of 0.54 V, Fill factor (FF) of 44.22% and solar power conversion efficiency (PCE) of 1.49% have been obtained for reference photovoltaic device. After introducing FLGS in the active layer with P3HT:PCBM blend, improvement of Jsc of 8.2 mA.cm−2, Voc of 0.57 V, FF of 42.15% and solar power conversion efficiency of 1.97% have been observed. The performance improvement in FLGS incorporated device compared to the reference device is attributed to the advantage of electron accepting feature and high electron transport capability of FLGS.

Abstract A new hybrid composite of activated carbon (AC)/multiwalled carbon nanotubes (MWCNTs)-ZnFe2O4 has been prepared by the modest and low-cost method for its application as supercapacitor electrode material. The carbon-based composite electrode gives excellent cycle stability with moderate capacitance. So the capacitance of carbon-based composite electrode could be further improved by incorporating metal oxides as they involve reversible redox reaction. In this regard, zinc ferrite (ZnFe2O4) among various metal oxides is being considered as important additive material towards supercapacitor (SC) applications owing to its excellent physical and chemical properties. Hence, ZnFe2O4 is integrated with the carbon composite of MWCNTs and AC for better SC performance and cycle stability. The composite has resulted in maximum specific capacitance of 613 F/g at 5 mV/s when measured from cyclic voltammetry (CV) in 3M KOH electrolyte. The measurement from galvanostatic charge-discharge (GCD) on synthesised composite has shown capacitance of 609 F/g at 1 A/g and that implying the significant storage performance of the prepared hybrid material. The stability, which is vital for the application of the composite, has been subjected for stability test and found that it retained 91% of the capacitance even after 10000 cycles. Further, the synthesised materials have been characterized by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH). The variation of current as a function of the applied voltage was analysed by current-voltage (I-V) measurements. These results suggest that the prepared composite can proficiently serve as a reliable choice for the electrode material for high-performance supercapacitor applications.

Few layers of electrochemically exfoliated graphene (FLECEG) of high quality have been synthesized by a modest method, and their composites with PEDOT:PSS and P3HT have been prepared by a simple solution process. The increase in filler FLECEG wt. % in the polymer has been observed to cause attractive modifications in the physical properties of all the composites, encouraging for their applications in energy systems. Conventional bulk heterojunction organic solar cells (OSCs) have been fabricated by separately using the composites as additional electrode layers and in the active layer of the device. A significant enhancement in the magnitude of device parameters of the OSCs due to the incorporation of FLECEG has been perceived compared with the corresponding reference devices. The caustic effects of intrinsic and additional extrinsic degradation processes on the output of the OSCs have been studied by periodically measuring the device's electrical properties under different environmental conditions. When compared with the performance of reference devices, OSCs manufactured by the application of the composites in both the charge transport layer and the active layer have been noticed to be sustaining with a remarkable stability, while the increment in power conversion efficiency is well maintained. This report has the potential to provide motivation for concentrating advanced research towards the development of composite materials for their applications in manufacturing more stable and efficient organic optoelectronic devices.

Abstract Carbon nanotubes (CNTs) have been synthesized by a simple and efficient pyrolysis technique, and composites of CNTs with PEDOT:PSS, and with P3HT:PCBM blend have been prepared by a modest solution treatment. Bulk heterojunction organic photovoltaic cell (OPVC) has been fabricated by spin coating technique with configuration ITO/PEDOT:PSS/P3HT:PCBM/Al to serve as reference OPVC. Three more OPVCs have been fabricated by the same procedure, the first one with CNTs/PEDOT:PSS composite replacing PEDOT:PSS, second one with CNTs/P3HT:PCBM composite replacing P3HT:PCBM blend, and the third one with both replacements. The performances of all the OPVCs at room temperature have been compared and CNTs have been observed to cause extraordinary increment in the power conversion efficiency (PCE) as well as other electrical parameters of all the devices depending on the layer in which they have been incorporated. To extend the study for understanding further advantages of CNTs incorporation in fighting against degradation, all the fabricated OPVCs have been exposed to open atmosphere and their electrical properties have been measured at room temperature in regular intervals. Encouragingly positive outcomes have been attained, demonstrating not only a well maintained enhancement in the PCE, but also a considerably improved device stability. The best performing OPVC has achieved 24% more PCE and 67% more lifetime in open atmosphere than the reference device, which clearly does indicate the significance of applications of filler CNTs to improve not only the performance but also the stability of OPVCs.

Graphene is an excellent 2D material due to its exceptional electrical properties which can be potentially used in optoelectronic. In order to use graphene in optoelectronics, the electrical properties need to be tuned. To tune electrical properties, few-layer graphene sheets (FLGS) prepared by electrochemical method have been used. The prepared FLGS has been characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform Infrared (FTIR), and Raman Spectroscopy. The optimized FLGS by characterization has been employed to tune the electrical properties in the presence and absence of water drop under ultraviolet and visible light. The obtained current of FLGS thin film is ~ 0.8mA whereas; the measured current under ultraviolet light is ~ 1.7mA and under visible light ~ 1.07mA. However, it has been observed that the measured current has decreased to under ...