Low Cost, High Performance Supercapacitor Electrode Using Coconut Wastes: Eco-Friendly Approach

Low cost, high performance supercapacitor electrodes were fabricated using coconut waste as precursor. Simple one step pyrolysis is adopted to get the spherical shaped particle where lignocellulosic nature of carbon converts into porous carbon nanospheres. Three types of coconut wastes, namely, coconut fiber (CF), coconut leaves (CL) and coconut stick (CS) have been studied and compared for their application in supercapacitors. Uniform spherical shape with particle size ranging from 30 to 60 nm for leaves and sticks and ∼20 nm for fibers was obtained. The electrochemical properties of the porous carbon nanospheres were studied using cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). The porous carbon nanospheres derived from all the three biowaste samples show good electrochemical performance for supercapacitor application. Porous carbon nanospheres derived from coconut fiber exhibited maximum specific capacitance of 236 F/g followed by coconut stick and coconut leaves with 208 and 116 F/g respectively at a scan rate of 2 mV/s. Further impedance studies showed a charge transfer resistance of 4.9 Ω for the porous carbon nanospheres derived from coconut fiber, while those from coconut leaves and coconut stick exhibited a slightly higher resistance of 6 and 14.2 Ω, respectively. The simple eco-friendly approach we have demonstrated for synthesizing coconut waste based carbon nanospheres makes them excellent candidates for future, low-cost, energy storage devices

Catalytic Activity Studies of Modified Alumina in the Esterification of Benzyl Alcohol with Different Aliphatic Acids

244-252<span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">A varied percentage of Fe, Co and Fe-Co mixtures were deposited on alumina support by dry impregnation method. The prepared materials were analyzed for their crystallinity, surface functional groups, morphology and elemental composition by P-XRD, FT-IR, and SEM-EDS techniques. Specific surface area of the catalytic materials was determined by BET technique using nitrogen as adsorbent. Further, surface acidity was estimated by TPD-NH3 and n- butylamine back titration method. The catalytic performances of these materials were checked in the esterification of benzyl alcohol with various aliphatic acids. The catalytic activity of Fe-Co/Al2O3 with 15% metal loading was found to be superior to other catalysts. The higher catalytic performance of the catalyst may be attributed to the higher surface acidity as well as synergetic effect of the metals. Further, the catalyst Fe-Co/Al2O3 (15%) was recyclable up to 5 times with negligible loss of its catalytic activity. A close relationship was noticed between surface acidity and catalytic performance of the materials.</span

Synthesis of carbon nanotubes over transition metal ions supported on Al(OH)₃

663-668Production of carbon nanotubes on bi-metallic (Fe/Co, Co/Ni, Fe/Ni, Fe/Mo, Co/Mo, Ni/Mo) and trimetallic (Fe/Co/Mo, Co/Ni/Mo, Fe/Ni/Mo) catalysts supported on Al(OH)₃ by catalytic chemical vapor deposition is reported. The support-catalyst systems have been prepared by incipient dry impregnation method and characterized by BET, powder XRD, SEM, and TG/DSC techniques. The carbon nanotubes have been synthesized by allowing C₂H₂ and N₂ to pass over a catalyst bed at 700°C placed on a quartz plate in a tubular furnace. The carbon deposit is examined using TEM. All the catalysts have been found to be active to different extents for the production of multiwall carbon nanotubes of varying thickness (10-15 nm). In the case of catalysts containing Fe/Co or Fe/Ni, a carbon deposit to an extent of 210 to 220% of the initial weight of the catalyst is obtained. This deposit also contains good quantities of carbon nanotubes. The tubes produced on nickel catalysts have been found to be thin and long. The effect of molybdenum on the nature of the carbon nanotubes produced is dependant on whether it is associated with one or two of the other transition metal ions supported over Al(OH)₃. To synthesize good quantities of carbon nanotubes, a binary mixture of Fe, Co and Ni without Mo is the best

A Study on Chemical and Lubrication Properties of Unrefined, Refined and Virgin Coconut Oil Samples

In the present work four samples each of unrefined coconut oil (URCO), refined coconut oil (RCO) and virgin coconut oil (VCO) samples collected from different places were evaluated in terms of physicochemical and lubrication parameters. The physicochemical properties of URCO, RCO and VCO were analyzed in terms of kinematic viscosity, Fatty acid profile, Iodine number, Saponification number, free fatty acid, Peroxide value and flash point. The lubrication properties of the oil samples were compared with the aid of four ball tester. The study revealed that fatty acid profile of VCO samples was slightly different from that of URCO and RCO samples. The saponification and Iodine value of VCO samples was also slightly lower than that of URCO and RCO samples. The four ball test results showed that the average coefficient of friction under tested condition was slightly less for URCO and VCO samples when compared to RCO samples. This difference in frictional property was due to the presence of free acid in the URCO and VCO which acted as boundary lubricant. The increased wear observed with VCO and URCO samples was linked to the presence of peroxides

A Study on Chemical and Lubrication Properties of Unrefined, Refined and Virgin Coconut Oil Samples

100-104In the present work four samples each of unrefined coconut oil (URCO), refined coconut oil (RCO) and virgin coconut oil (VCO) samples collected from different places were evaluated in terms of physicochemical and lubrication parameters. The physicochemical properties of URCO, RCO and VCO were analyzed in terms of kinematic viscosity, Fatty acid profile, Iodine number, Saponification number, free fatty acid, Peroxide value and flash point. The lubrication properties of the oil samples were compared with the aid of four ball tester. The study revealed that fatty acid profile of VCO samples was slightly different from that of URCO and RCO samples. The saponification and Iodine value of VCO samples was also slightly lower than that of URCO and RCO samples. The four ball test results showed that the average coefficient of friction under tested condition was slightly less for URCO and VCO samples when compared to RCO samples. This difference in frictional property was due to the presence of free acid in the URCO and VCO which acted as boundary lubricant. The increased wear observed with VCO and URCO samples was linked to the presence of peroxides

Study on Effect of Aging and Aging Temperature on Frictional Properties of Coconut Oil Samples

376-380The present study evaluates the effect of aging and aging temperature on the frictional properties of Unrefined Coconut oil (URCO), Refined Coconut oil (RCO) and Virgin Coconut oil (VCO) samples using four ball tester. It was observed that the variations in the physicochemical properties of fresh URCO, RCO and VCO samples were attributed to the difference in their composition. This study showed that URCO, RCO and VCO samples followed same trend in their physicochemical and tribological properties when subjected to aging. The drop in flash point of aged oil samples with aging was attributed to the increased content of free fatty acids generated due to the degradation of triglyceride molecules. It was observed that the degradation of peroxide molecules has resulted in  the stabilization in the  peroxide content of  URCO, RCO and VCO samples when aged at 100 0C

A Comparative Study on Electrochemical Behaviour of Co3O4 and Co3O4-MWCNTs for Supercapacitors

Co3O4 and Co3O4/MWCNTs were prepared by hydrothermal process under autogenous pressure in Teflon lined autoclave and calcined at 250 degrees C. Both samples were characterized by PXRD, FT-IR, SEM-EDS, TEM & FT-Raman to evaluate their surface and bulk properties. The PXRD pattern of the materials indicated the formation of cubic phase of Co3O4. FT-IR results showed the presence of metal oxygen bond in the samples. The SEM and TEM images of the Co3O4 / MWCNTs indicated spherical and cubic aggregates of metal oxide particles (10-30 nm) decorated both on the surface and inside the tubes of carbon nanotubes. The characteristic Ig and Id (graphitic and defects) Raman bands indicated the retention of tubular structure of MWCNTs even after the deposition of Co3O4. The calcined Co3O4-MWCNTs composites and Co3O4 exhibited specific capacitance of 284 & 205 F/g at a sweep rate of 2mVs(-1) in 6M KOH by cyclic voltammetry. The psuedocapacitance performances of calcined Co3O4-MWCNTs were found to be better than Co3O4. Chronopotentiometric studies made for the materials at a current density of 500mA/g indicated 100% columbic efficiency at 2000th cycle for Co3O4/ MWCNTs which is a better electrode material than Co3O4

<span style="font-size:15.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-GB">A Comparative Study on Electrochemical Behaviour of Co₃O₄and Co₃O₄-MWCNTs for Supercapacitors</span>

202-208Co3O4 and Co3O4/MWCNTs were prepared by hydrothermal process under autogenous pressure in Teflon lined autoclave and calcined at 2500C. Both samples were characterized by PXRD, FT-IR, SEM-EDS, TEM & FT-Raman to evaluate their surface and bulk properties. The PXRD pattern of the materials indicated the formation of cubic phase of Co3O4. FT-IR results showed the presence of metal oxygen bond in the samples. The SEM and TEM images of the Co3O4 / MWCNTs indicated spherical and cubic aggregates of metal oxide particles (10-30 nm) decorated both on the surface and inside the tubes of carbon nanotubes. The characteristic Ig and Id (graphitic and defects) Raman bands indicated the retention of tubular structure of MWCNTs even after the deposition of Co3O4. The calcined Co3O4-MWCNTs composites and Co3O4 exhibited specific capacitance of 284 & 205 F/g at a sweep rate of 2mVs-1 in 6M KOH by cyclic voltammetry. The psuedocapacitance performances of calcined Co3O4-MWCNTs were found to be better than Co3O4. Chronopotentiometric studies made for the materials at a current density of 500mA/g indicated 100% columbic efficiency at 2000th cycle for Co3O4 / MWCNTs which is a better electrode material than Co3O4.</sub

A comparative study on electrochemical performance of KOH activated carbons derived from different biomass sources - Musa acuminata stem, Pongamia pinnata seed oil extract cake, cajanus cajan stem and Asclepias syriaca floss

In the present scenario of research, the recycling of inexpensive widely available agricultural waste/biowaste to activate carbon (AC) and procurement of value-added product has significant impact on energy storage systems, particularly in Electrochemical double layer capacitors (EDLCs). Herein, we report the production of KOH activated carbons from different biomass sources such as Musa Acuminata stem (MAC), Pongamia pinnata seed oil extract cake (PPC), Cajanus Cajan stem (CCC) and Asclepias syriaca floss (ASC) for the said purpose. Initially, the biomass materials were pyrolyzed at 550 °C and then activated with KOH at 800 °C. All the carbon materials were characterized for their physico-chemical properties by various analytical techniques and compared. Further, these materials were studied for their electrochemical performance using suitable electro-analytical techniques in 1 M KOH solution. ACs (Activated carbons) derived from MAC, PPC, CCC &amp; ASC were estimated in three electrode system and were found to exhibit a specific capacitance (Cs) of 358, 343, 355 &amp; 540 F/g at a scan rate of 2 mV/s and 102, 188, 253 &amp; 256 F/g at a current density of 2.5 A/g respectively. The main novel objective of this work is to correlate the morphological and surface properties of these ACs obtained from different biomass sources with electrochemical performance. A symmetric coin cell constructed with ASC material exhibited Cs of 67 F/g at a current density of 2.5 A/g with maximum energy &amp; power densities (ED &amp; PD) of 37.2 W h/kg and 19.9 kW/kg respectively. Further the cell showed 25,000 cycles stability with 86% Cs retention and 100% coulombic efficiency