Browsing by Author "Madhusree, J.E."

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High-performance hybrid supercapacitor-immobilized Wells-Dawson polyoxometalates on activated carbon electrodes
(Royal Society of Chemistry, 2023) Madhusree, J.E.; Chandewar, P.R.; Shee, D.; Mal, S.S.
The nanofabrication of electroactive hybrid materials for next-generation energy storage devices is becoming increasingly significant as supercapacitor (SC) technology develops rapidly. The present study utilizes activated carbon (AC) templates reinforced with Wells-Dawson polyoxotungstates (POMs) to produce nanohybrid electrodes for high-performance supercapacitors. This study analyzes Wells-Dawson polyoxotungstates (P2W18) for the first time integrated with AC, and its structural and electrochemical performances are discussed. First, the electrochemical performances of symmetric supercapacitors were characterized in an acidic aqueous electrolyte (0.5 M H2SO4). It was observed that a supercapacitor cell containing the 5 wt% AC-P2W18 hybrid symmetric displayed a noteworthy specific capacitance of 289 F g−1 and a remarkable energy density of 40 W h kg−1. Moreover, 5% AC-P2W18 symmetric supercapacitor cells showed 89% cyclic stability over 4000 cycles. Three LED lights were charged onto the electrode. The LEDs continued to illuminate continuously for red until 160 seconds, yellow until 20 seconds, and blue until 10 seconds after removing the electrode from the electrochemical workstation, demonstrating the device's power and energy density. © 2023 The Royal Society of Chemistry.
Organic-inorganic hybrid mixed-valent bisphosphonate-polyoxovanadates composites with activated carbon for energy storage applications
(Nova Science Publishers, Inc., 2024) Madhusree, J.E.; Banerjee, A.; Mal, S.S.
In this book, we discuss the investigation of two different bisphosphonate-functionalized polyoxovanadate compounds for use in electrochemical energy storage applications. The compounds are (NH4)4[H6(VIVO2)(VV2O5)2O3P-C(O)(CH2-2-C5NH4)-PO32].9H2O (m), and (NH4)4[H6(VIVO2)(VV2O5)2O3P-C(O)(CH2-3-C5NH4)-PO32]. 8H2O (n). They have a mixed-valent oxovanadate polyanionic assembly that has two different pyridyl functional groups present on the organic bisphosphonate ligand. Several techniques have been used to characterize composites made from these compounds with activated carbon, including Fourier transform infrared spectroscopy, P-XRD, FESEM, EDX, and surface adsorption-desorption tests. The electrochemical performance of acidic electrolytic solutions containing 0.1 M H2SO4, AC-m, and AC-n electrode materials was investigated. Although the compounds are isotypic mixed-valence polyoxovanadate structures, their electrical behavior varies based on the position of the pyridyl group. AC-n was reported to have the most prominent specific capacitance of 313 F g-1 at a current density of 1 A g-1 in a voltage window of 0-1 V, with exceptional energy and power densities of 43.56 Wh kg-1 and 1999.72 W kg-1, respectively. At the same time, AC-m exhibited a specific capacitance of 212 F g-1 and a specific energy of 29.45 Wh kg-1. By lighting up different LED lights with only 42 mg of carbon clothcoated sample, the composite AC-n electrode displayed exceptional specific power. A further benefit of AC-n nanohybrids is their ability to retain electrochemical performance over time, which suggests long-term stability. © 2024 Nova Science Publishers, Inc. All rights reserved.
Polyoxometalate-based materials for the effluent treatment of removing heavy metals in the water pollutants: mini review
(Springer Science and Business Media Deutschland GmbH, 2023) Madhusree, J.E.; Mal, S.S.
Water contamination is a big concern nowadays due to increased human activity and the quick expansion of modern industry and agriculture. In our current environment, heavy metal pollution has become a primary concern. Treatment of heavy metals is especially significant, because these metals absorb into biological cells and can lead to severe illness and disorders. Several studies have been conducted over the last several years to remove heavy metals from wastewater using various strategies and materials. Among those strategies, complexation's reaction and the electrochemical sensor are attractive because of their excellent metal selectivity, cost-effectiveness, short analytical time, and high removal efficiency. Polyoxometalates (POMs) are a group of metal–oxygen cluster compounds with extremely electronegative and oxo-enriched surfaces and variable structure and size. POMs have drawn much interest in removing toxins from wastewater due to their electrical and physical characteristics. The removal of heavy metals from wastewater is covered in this review using POM and POM-based MOF nanocomposites in various treatment methods like complexation and electrochemical sensor, which have the advantages of high removal efficiency, excellent metal selectivity, in-expansive, and rapid analytical times. © 2023, King Abdulaziz City for Science and Technology.
Wells-Dawson Polyoxometalate Modified Lignin Derived High Surface Area Activated Carbon Electrode Materials for Energy Storage Application
(John Wiley and Sons Inc, 2024) Madhusree, J.E.; Athulya, K.; Chandewar, P.R.; Shee, D.; Mal, S.S.
Supercapacitors have emerged as a potential technology in the search for energy storage solutions, delivering astounding performance, environmental sustainability, safety, and economic feasibility. Biomass-derived activated carbon electrodes have received much interest in this area because of their inherent mechanical stability and eco-friendliness. While Wells-Dawson POMs exhibit excellent redox properties for electrochemical performance, however, their solubility nature leads to poor conductivity. Biomass-derived activated carbon was employed as a solid support material to address this issue, which offers high surface area and cost-effectiveness. This work explores the synthesis of new nanofabricated electrodes by adding vanadium-substituted Wells-Dawson polyoxometalates (P2VW17) to activated carbon derived from lignin (LDAC). In depth, we investigated these novel nanohybrid material's structural properties and electrochemical performance. Furthermore, electrochemical testing was performed for 20 wt % LDAC-P2VW17 in a 0.25 M H2SO4 electrolyte. The 20 wt % LDAC-P2VW17 supercapacitor cell has an excellent specific capacitance of 216.48 F g−1, with great energy and power densities of 30.06 Wh kg−1 and 1999.98 W kg−1. Additionally, it has an excellent capacitance retention of 94.4 % over 4000 cycles with 82.6 % columbic efficiency. A test for practical application has been conducted on 20 wt % LDAC-P2VW17. The first series of LEDs were connected to the workstation and took hold of 30 seconds to discharge. A piezoelectric buzzer was subjected to a trial as part of our testing procedure. Upon integration with our system, the buzzer produced an audible tone that persisted for 140 seconds. © 2024 Wiley-VCH GmbH.