This work focuses on the development of a novel type of chemically activated carbon networks composited with the graphene oxide. Here, the carbon networks were derived from green biomass wastes such as orange peels, banana peels and potato starch. All the obtained carbon materials were being activated using different activating agents based on the higher specific capacitance such as phosphoric acid activated orange peel derived carbon, sulphuric acid activated banana peel derived carbon and hydrochloric acid activated potato starch. Further they were individually composited with graphene oxide for enhanced performance. Different chemical activation is employed for the sake of obtaining higher specific capacitance, energy and power density. Phosphoric acid activation on orange peel derived carbon network was selected due to the improvement in the micropores and further increased the surface area with the controlling capability of structures of activated carbon. To improve the conductivity of the samples, graphene oxide was added. The electrochemical performance of orange peel, banana peel and potato starch derived nano porous activated carbon materials composited with graphene oxide for supercapacitor applications is evaluated using aqueous H2SO4 electrolytes at a scan rate of 10 mV s-1. The samples that are prepared are structurally characterized using fourier transform infrared spectroscopy, x-ray diffraction and electrochemically characterized using cyclic voltammetry, galvanostatic charge and discharge measurements, and electrochemical impedance spectroscopy. From the electrochemical measurements, suitability of material as electrode for supercapacitors can be understood. The superior electrochemical performance is attributed in orange peel derived nano porous carbon/ graphene oxide due to porous structure.

Because of the increasing demands in energy, growth in alternate energy sources is inevitable. By activation followed by carbonization of starch of solanum tuberosum makes a porous carbon network as electrode material for supercapacitor. To achieve an improvement in specific capacitance, activating the starch of solanum tuberosum using chemicals such as hydrochloric acid, phosphoric acid and sulphuric acid were done. The structural and electrochemical performance of activated carbon derived from the starch of solanum tuberosum is evaluated using FTIR, XRD, CV, GCD and EIS. The improved performance of chemically treated starch of solanum tuberosum in energy storage mechanism is ascribed to fast ionic diffusion of the electrolyte into and out of the pores. From the CV analysis, the higher specific capacitance (94 F.g-1) is obtained for sulphuric acid treated activated carbon derived from the starch of solanum tuberosum with good capacity retention ratio. From GCD analysis, 78.3, 56.7, 82.7 and 74.9 Fg-1 of specific capacitance is obtained for POC, POCH, POCP and POCS, respectively. When compared to all the prepared samples, POC exhibited small equivalent series resistance and POCS exhibited small charge transfer resistance.

Supercapacitor electrodes synthesized from activated carbon (AC) has high energy and power capabilities as they have larger surface area, greater conductivity, and also AC has the ability to optimize the properties of supercapacitors. Supercapacitor has gained its attention due to its fast charging/discharging speed and long‐term stability than the normal batteries. In this work, GO/PPy/AC composite electrodes was synthesized to increase the specific capacitance and the energy storage capability of supercapacitor through modified hummers’ method, sacrificial template polymerization method, and hydrothermal method. Here, the AC was derived from seeds of Ziziphus jujuba and shells of Prunus dulcis. The performances of GO, GO/PPy, GO/PPy/ACZJ, and GO/PPy/ACPD electrodes were evaluated using 6 M KOH electrolyte at different current densities and scan rates. The electrochemical properties of the electrodes were characterized by CV, GCD, and EIS analysis to study the suitability of the electrode material. GO/PPy/ACPD electrode exhibited the specific capacitance of 1217.1, 456.67, 270.44, and 90.88 F g^-1 with current densities of 1, 2, 4, and 10 A g^-1, respectively. GO/PPy/ACPD has high specific capacitance of 1217.1 F g^-1 at 1 A g^-1. The enhanced electrochemical performance is due to better surface area and higher specific capacitance.

Design and Fabrication of Flexible Nanoantenna-Based Sensor Using Graphene-Coated Carbon Cloth: Carbon nanomaterials have attracted significant consideration and concern due to the unique chemical and physical properties. Recently, nanodiamonds, graphene, and carbon nanotubes are served as electrodes, hydrogen storage elements, and composite materials. In this work, a 5GHz graphene nanoantenna that falls inside the very-small-aperture terminal (VSAT) C-band range has been fabricated. A graphene substrate with a thickness of h=0.5cm is formed which is then used for fabricating a graphene nanoantenna working at 5GHz. To design and simulate the antenna, Analysis System (ANSYS) electromagnetic desktop software was used. Using the designed graphene antenna, the parameters such as voltage standing wave ratio, three-dimensional radiation pattern, and directivity were obtained. After designing of the antenna using ANSYS software, it was physically fabricated. The graphene was used as a dielectric, copper sheet acted as a patch over as well as ground. Finally, the design was testedusing Vector Network Analyzer (Model: N9925A) and the transmission range was found as 5GHz.

The objective of this study is the design, simulation, and performance optimization of a micromixer device using the three input parameters of device structure, flow rate and diffusion coefficient of gold nanoparticles while the output parameters are concentration, velocity, pressure and time domain analysis. Each input parameter in the microfluidic chip influences the system output. The data were gathered through extensive study in order to optimize the diffusion control. The fuzzy logic approach is used to optimize the performance of the device with respect to the input parameters. In this study, we have chosen three different flow rates of 1, 5, and 10 μL min⁻¹, three different diffusion coefficient values of low, average and high diffusivity gold nanofluids (15.3 e⁻¹², 15.3 e⁻¹¹, 15.3 e⁻¹⁰ m² s⁻¹) which are used in three different shapes of micromixer device, Y-shaped straight channel micromixer, herringbone-shaped micromixer, and herringbone shape with obstacles micromixer, and we measured the output performance, such as mixing efficiency, pressure drop, concentration across the microchannel and time domain. The data were obtained by fuzzy logic analysis and it was found that the herringbone shape with obstacles micromixer shows 100% mixing efficiency within a short duration of 5000 μm, and complete mixing was achieved within 10 seconds with a low pressure drop of 128 Pa.