Browsing by Author "Sangeetha, D.N."

Now showing 1 - 6 of 6

h-MoO 3 /Activated carbon nanocomposites for electrochemical applications
(2019) Sangeetha, D.N.; Krishna, Bhat, D.; Selvakumar, M.
MoO 3 nanorods were synthesized through the microwave method and the nanocomposites of MoO 3 /activated carbon were prepared for supercapacitor and hydrogen evolution reaction (HER). The XRD pattern revealed that the prepared MoO 3 has a hexagonal phase (h-MoO 3 ). The as-prepared h-MoO 3 was composited with activated carbon (AC) and tested for supercapacitor studies. The fabricated supercapacitor exhibited an appreciable specific capacitance, power density, and energy densities. Further, dedoping of nitrogen in the doped AC creates defects on AC (DAC). These DAC/MoO 3 nanocomposites were prepared and tested for its electrocatalytic activity towards hydrogen evolution reactions. DAC/MoO 3 nanocomposite showed much higher electrocatalytic activity than the neat MoO 3 . [Figure not available: see fulltext.]. 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
h-MoO 3 /Activated carbon nanocomposites for electrochemical applications
(Institute for Ionics ww@tf.uni-kiel.de, 2019) Sangeetha, D.N.; Krishna Bhat, D.; Muthu, M.
MoO 3 nanorods were synthesized through the microwave method and the nanocomposites of MoO 3 /activated carbon were prepared for supercapacitor and hydrogen evolution reaction (HER). The XRD pattern revealed that the prepared MoO 3 has a hexagonal phase (h-MoO 3 ). The as-prepared h-MoO 3 was composited with activated carbon (AC) and tested for supercapacitor studies. The fabricated supercapacitor exhibited an appreciable specific capacitance, power density, and energy densities. Further, dedoping of nitrogen in the doped AC creates defects on AC (DAC). These DAC/MoO 3 nanocomposites were prepared and tested for its electrocatalytic activity towards hydrogen evolution reactions. DAC/MoO 3 nanocomposite showed much higher electrocatalytic activity than the neat MoO 3 . [Figure not available: see fulltext.]. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
High power density and improved H2 evolution reaction on MoO3/Activated carbon composite
(2019) Sangeetha, D.N.; Holla, R.S.; Ramachandra, Bhat, B.; Selvakumar, M.
The formation of hexagonal MoO3 (h- MoO3) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO3/plastic bottle derived activated carbon (PAC) composite in 1 M Na2SO4 aqueous electrolyte. The operating voltage for the aqueous electrolyte was maximized to 1.6 V with this combination. The wide operating voltage led to a maximum specific capacitance of 211 Fg-1, power density of 287 W kg?1 and 79% efficiency even at 5000 charge-discharge cycles for the hybrid supercapacitor combination. The combined effect of PAC micropores along with the 1-D rod-shaped h-MoO3, helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO3 when tested for hydrogen evolution reactions (HER), provided lesser onset potential and Tafel slope values of ?0.23 mV and ?93 mVdec?1. There was a change in the structural environment of carbon due to the heteroatom doping and dedoping producing defects in PAC, termed as PDAC. These defects together with the hexagonal microrods of MoO3 provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H2. 2019 Hydrogen Energy Publications LLC
High power density and improved H2 evolution reaction on MoO3/Activated carbon composite
(Elsevier Ltd, 2020) Sangeetha, D.N.; Holla, R.S.; Badekai Ramachandra, B.; Muthu, M.
The formation of hexagonal MoO3 (h- MoO3) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO3/plastic bottle derived activated carbon (PAC) composite in 1 M Na2SO4 aqueous electrolyte. The operating voltage for the aqueous electrolyte was maximized to 1.6 V with this combination. The wide operating voltage led to a maximum specific capacitance of 211 Fg-1, power density of 287 W kg?1 and 79% efficiency even at 5000 charge-discharge cycles for the hybrid supercapacitor combination. The combined effect of PAC micropores along with the 1-D rod-shaped h-MoO3, helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO3 when tested for hydrogen evolution reactions (HER), provided lesser onset potential and Tafel slope values of ?0.23 mV and ?93 mVdec?1. There was a change in the structural environment of carbon due to the heteroatom doping and dedoping producing defects in PAC, termed as PDAC. These defects together with the hexagonal microrods of MoO3 provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H2. © 2019 Hydrogen Energy Publications LLC
Improving hydrogen evolution reaction and capacitive properties on CoS/MoS2 decorated carbon fibers
(2019) Sangeetha, D.N.; Krishna, Bhat, D.; Senthil, Kumar, S.; Selvakumar, M.
We report a facile method to transform abundantly dumped banana stem fibers into carbon fibers (CFs) useful for energy applications. The CFs surface area is increased by varying the quantity of KOH activation to 488 m2g-1. The solvothermal method is used to synthesize CoS, CoS/MoS2 and also grown on the activated carbon fibers (ACFs). Nano nodules of CoS arranged into sheets and layers of MoS2 stacked together were found in FESEM analysis. The morphology of the CoS/MoS2 differs when grown on ACFs. The growth of CoS/MoS2 along the ACFs length prevents any stacking of the pseudocapacitance materials. The ternary composite ACFs/CoS/MoS2 exhibits superior supercapacitor behavior as well as hydrogen evolution reaction (HER) due to the synergetic effect of the conducting ACF surface and redox active CoS/MoS2. A maximum specific capacitance of 733 Fg-1, energy and power density of 33 WhKg?1 and 999 WKg-1 respectively are obtained. A low Tafel slope value of 61 mVdec?1 is obtained for the ACFs/CoS/MoS2 ternary composite electrode. The present work therefore offers a fresh insight into the effective conversion of waste materials into electrode material for energy storage and conversion applications. 2019 Hydrogen Energy Publications LLC
Improving hydrogen evolution reaction and capacitive properties on CoS/MoS2 decorated carbon fibers
(Elsevier Ltd, 2020) Sangeetha, D.N.; Krishna Bhat, D.; Senthil Kumar, S.; Muthu, M.
We report a facile method to transform abundantly dumped banana stem fibers into carbon fibers (CFs) useful for energy applications. The CFs surface area is increased by varying the quantity of KOH activation to 488 m2g-1. The solvothermal method is used to synthesize CoS, CoS/MoS2 and also grown on the activated carbon fibers (ACFs). Nano nodules of CoS arranged into sheets and layers of MoS2 stacked together were found in FESEM analysis. The morphology of the CoS/MoS2 differs when grown on ACFs. The growth of CoS/MoS2 along the ACFs length prevents any stacking of the pseudocapacitance materials. The ternary composite ACFs/CoS/MoS2 exhibits superior supercapacitor behavior as well as hydrogen evolution reaction (HER) due to the synergetic effect of the conducting ACF surface and redox active CoS/MoS2. A maximum specific capacitance of 733 Fg-1, energy and power density of 33 WhKg?1 and 999 WKg-1 respectively are obtained. A low Tafel slope value of 61 mVdec?1 is obtained for the ACFs/CoS/MoS2 ternary composite electrode. The present work therefore offers a fresh insight into the effective conversion of waste materials into electrode material for energy storage and conversion applications. © 2019 Hydrogen Energy Publications LLC