Browsing by Author "Kour, Pawanpreet"

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All-redox hybrid supercapacitors based on carbon modified stacked zinc cobaltite nanosheets
(Royal Society of Chemistry, 2023-09-12T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.
The role of energy in the present century has increased with the fast advancement of the global economy. In this regard, hybrid supercapacitors (HSCs) as energy storage systems have become an extensive research focus worldwide. This study reports the synthesis of carbon-loaded ZnCo2O4 stacked nanosheets via an in situ hydrothermal process followed by annealing. The electrochemical response was tested in a 2-electrode system. The optimized composite exhibited a capacitance of ?527.6 F g?1 at 5 mV s?1. The symmetric SC (SSC) possessed an energy density (Ed) of ?17.3 W h kg?1 corresponding to a power density (Pd) of 2.25 kW kg?1. Two asymmetric all-redox HSCs have also been fabricated using an optimized composite material as the positive electrode. The previously synthesized MnCo2O4/AC (HSC1) and MnO2/AC (HSC2) were taken as negative electrodes. HSC1 exhibited an Ed of ?24.4 W h kg?1 corresponding to a Pd of ?0.8 kW kg?1. On the other hand, HSC2 exhibited the highest Ed of ?30.8 W h kg?1 at 2.4 kW kg?1. The real-time application of the composite is tested with the fabricated HSCs. HSC1 exhibited a capacitive retention of ?72.2% after 10 000 cycles. On the other hand, HSC2 exhibited a capacitive retention of ?73.4% after 10 000 cycles. The SSC, HSC1, and HSC2 illuminated a 39 red LED panel for ?3 min, 7 min, and 13 min, respectively. The results suggested the promising performance of all-redox HSCs. The overall results present a sustainable approach for creating hierarchical energy materials for the construction of future energy-storage systems. � 2023 The Royal Society of Chemistry.
BiFeO3/g-C3N4/f-CNF ternary nanocomposite as an efficient photocatalyst for methylene blue dye degradation under solar light irradiation
(Elsevier Ltd, 2023-06-21T00:00:00) Deeksha; Kour, Pawanpreet; Ahmed, Imtiaz; Haldar, Krishna Kanta; Yadav, C.S.; Sharma, Surender Kumar; Yadav, Kamlesh
The development of Perovskite oxide photocatalysts with superior dye degradation efficiency under solar light irradiation has gained attention in recent years, owing to their extraordinary flexibility, chemical composition, and tunability. Herein, we report the facile synthesis of a novel ternary composite composed of BiFeO3 (BFO) perovskite, g-C3N4, and functionalized carbon nanofibers (f-CNF), referred to as BFO/g-C3N4/f-CNF using a simple solution method as a photocatalyst to accelerate the degradation of methylene blue dye. Detailed structural and microstructural features confirm the formation of a ternary composite composed of BFO nanoparticles and f-CNFs mounted on g-C3N4 nanosheets. The photocatalytic activity of the sample for the degradation of methylene blue dye was studied in solar light using UV�visible spectroscopy. The BFO/g-C3N4/f-CNF ternary composite displays excellent photocatalytic activity with a degradation rate of 87 % after illumination for 120 min under solar light than BFO, g-C3N4, and binary composites BFO/g-C3N4 and BFO/f-CNF. The highest rate constant (k = 0.01675 min?1) for BFO/g-C3N4/f-CNF further confirms improved photocatalytic efficiency. The red shift in the UV�visible absorption spectrum of BFO/g-C3N4/f-CNF indicates a reduced band gap (1.9 eV) compared to that of pure BFO (2.28 eV) and g-C3N4 ( 2.72 eV). A decrease in the photoluminescence intensity of the ternary composite compared to that of BFO indicates the inhibition of photoexcited electron recombination which results in the availability of more charge carriers for the photocatalytic process. The enhanced efficiency of BFO/g-C3N4/f-CNF can be explained by the synergistic effect between BFO and g-C3N4 and the incorporation of f-CNF further promotes the migration rate of electrons from BFO to g-C3N4. � 2023 Elsevier B.V.
Effects of Dy3+-doping on the band-gap widening and formation of mixed cubic and monoclinic phases of Sm2O3 nanoparticles
(Springer Science and Business Media Deutschland GmbH, 2023-10-30T00:00:00) Sain, Rachana; Roy, Ayan; Kumar, Ajay; Anu; Deeksha; Kour, Pawanpreet; Singh, Ravi Pratap; Yadav, Kamlesh
We synthesized Sm2?xDyxO3 (where X = 0.00, 0.03, 0.06, 0.09, and 0.12) nanoparticles using a co-precipitation method and investigated their structural and optical properties. X-ray diffraction (XRD) results reveal that Dy3+-doping in Sm2O3 nanoparticles leads to the formation of a monoclinic polymorphic phase along with the cubic phase of Sm2O3 and its fraction increases with increasing Dy3+-doping concentration. The substitution of Dy3+ at the Sm3+ site converts the cubic Sm2O3 unit cells into distorted monoclinic Sm2?XDyXO3 unit cells. The average crystallite and nanoparticle sizes decrease with increasing Dy3+-doping concentration. Dy3+-ions act as particle size inhibitors, which is attributed to an increase in the segregation of Dy3+-dopant ions at the surface of the nanoparticles with increasing Dy3+-doping content. The peak appearing at 851�cm?1 in the Fourier transform infrared spectroscopy (FTIR) spectra confirms the formation of Sm2O3. Widening of the band gap (Eg) above the band gap of pure cubic Sm2O3 with Dy3+-doping concentration has been observed for X > 0.06, which is due to the Moss-Burstein and quantum size effects. � 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
Effects of Interfacial Interactions and Nanoparticle Agglomeration on the Structural, Thermal, Optical, and Dielectric Properties of Polyethylene/Cr2O3 and Polyethylene/Cr2O3/CNTs Nanocomposites
(Springer, 2022-11-22T00:00:00) Gupta, Jaya; Kumar, Ajay; Roy, Ayan; Anu; Deeksha; Kour, Pawanpreet; Singh, Ravi Pratap; Yogesh, Gaurav Kumar; Yadav, Kamlesh
In this report, we have synthesized the binary and ternary phase nanocomposites [(polyethylene (PE)1?X/(Cr2O3)x) and (PE)1?X/(Cr2O3)X/CNTs (where X = 0,�2%, 4%, 6%, 8%, and 10%)] using the melt mixing method and studied the structural, optical, thermal and dielectric properties with an increase in Cr2O3 nanofiller concentration. Our results show an increase in interfacial interactions between Cr2O3 nanofiller and PE matrix with an increase in nanofiller concentration up to X = 6%. After that, the interactions decreased with a further increase in X because of the increase in the size of the Cr2O3 nanoparticle aggregates. Incorporating 2% carbon nanotubes (CNTs) into (PE)1?X/(Cr2O3)X nanocomposites, further decreases the interactions between the Cr2O3 nanofiller and the PE matrix. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Effects of interfacial interactions on structural, optical, thermal degradation properties and photocatalytic activity of low-density polyethylene/BaTiO3 nanocomposite
(Elsevier Ltd, 2023-04-10T00:00:00) Roy, Ayan; Panda, Sambit; Gupta, Jaya; Anu; Singh, Ravi Pratap; Deeksha; Kour, Pawanpreet; Sharma, M.P.; Yadav, Kamlesh
Barium titanate (BaTiO3) filled low density polyethylene (LDPE), (LDPE)100?x/(BaTiO3)x (where x = 0, 2, 4, 6 and 10) nanocomposites are prepared via a solvent-free melt-mixing method. The effects of nano-sized BaTiO3 (nBT) on the structural, optical and thermal degradation properties of LDPE are investigated to address the qualitative interfacial interaction effects due to the spatial distribution of nBT particles in the LDPE matrix. X-ray diffraction (XRD) results confirm the uniform dispersion of nBT nano-fillers in the LDPE polymer matrix. The crystallite size of LDPE increases with increasing the nBT content. Fourier transform infrared spectroscopy (FTIR) results indicate the enhancement in interfacial physical interactions between the polymer and nano-fillers with increasing nano-filler content. The band gap energy of the nanocomposites decreases with increasing nano-filler content, which suggests chemical imperfections close to the interfaces. DSC results depict higher Tm values for the composites which is attributed to the heterogeneous nucleating effects of the nBT particles. Thermo-gravimetric analysis (TGA) results indicate an increase in the decomposition temperature (TD), thermal stability and good dispersibility probability of nBT with increasing nBT. The photocatalytic decomposition of MB is highest (73.52%) for the 10% nBT incorporated LDPE nanocomposite sample. These results correlate with the effect of the interfacial interactions between the nBT fillers and the LDPE polymer matrix. � 2023 Elsevier Ltd
Electrochemical performance of mixed-phase 1T/2H MoS2 synthesized by conventional hydrothermal v/s microwave-assisted hydrothermal method for supercapacitor applications
(Elsevier Ltd, 2022-07-05T00:00:00) Kour, Pawanpreet; Deeksha; Yadav, Kamlesh
Mixed-phase 1T/2H MoS2 has been receiving immense attention as an electrode material for supercapacitors due to the synergistic effects of both the phases. Herein, we synthesized mixed-phase 1T/2H MoS2 via two different techniques: conventional hydrothermal (HT) and microwave-assisted hydrothermal (MHT) technique. The formation of MoS2 is confirmed through X-ray diffraction pattern, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman-spectra, and X-ray photoelectron spectra. The electrochemical performance of the two samples is investigated using cyclic voltammetry (CV), Gravimetric charging-discharging (GCD) and electrochemical impedance spectroscopy (EIS). MoS2 synthesized via MHT method (MS-MW) and HT method (MS-HT) deliver capacitances of 421 F g?1 and 742 F g?1 at 5 mV s?1, respectively. The energy density of MS-HT (57 Wh kg?1) is almost double than that of MS-MW (30 Wh kg?1). MS-HT also exhibited remarkable capacitance retention of 91% over 1200 cycles, compared with MS-MW. The results demonstrate that MoS2 synthesized by the hydrothermal method delivers superior electrochemical performance. � 2022 Elsevier B.V.
Hierarchical template-free chestnut-like manganese cobaltite for high-performance symmetric and asymmetric supercapacitor
(Elsevier B.V., 2022-11-25T00:00:00) Kour, Simran; Tanwar, Shweta; Kour, Pawanpreet; Sharma, A.L.
In this work, template-free Chestnut-like MnCo2O4 microspheres are synthesized using a straight-forward hydrothermal process succeeded by calcination. Urea as a reducing/precipitating agent can play an essential role in controlling the morphology of the material without using any additional surfactants or templates. The effect of reducing agent (Urea) on the structural and morphological evolution of MnCo2O4 has been studied. The electrochemical performance of the synthesized materials is investigated in a real device two-electrode cell configuration (symmetric and asymmetric system) rather than a three-electrode configuration. The two-electrode system gives more accurate and practical evaluation of the capacitive behavior of the material. The MnCo2O4 displayed the highest capacitance of 245.34 F g?1 at 5 mV s?1 for 0�1 V in a symmetric cell configuration. It also held an energy density of 22.24 Wh kg?1 at 1500 W kg?1. The optimized sample showed outstanding cyclic performance with only 3% of capacitance loss after 5000 cycles. Based on the structural and electrochemical findings, a charge storage mechanism has been proposed for the symmetric SC. Furthermore, a hybrid asymmetric supercapacitor with MnCo2O4 as a cathode and the previously synthesized MnO2/AC as an anode is also fabricated which exhibited an energy response of 30.12 Wh kg?1 for a power of 7000 W kg?1. For practical applications, different colored LEDs (red, yellow, green, and blue) and a panel with six red LEDs have been illuminated. The panel with six red LEDs is illuminated for 12 mins. for symmetric supercapacitor and 18 mins. for asymmetric supercapacitor. All these remarkable outcomes suggested that the synthesized material has wide potential for supercapacitors. � 2022
LaCoO3Perovskite Nanoparticles Embedded in NiCo2O4Nanoflowers as Electrocatalysts for Oxygen Evolution
(American Chemical Society, 2022-11-08T00:00:00) Kubba, Deeksha; Ahmed, Imtiaz; Kour, Pawanpreet; Biswas, Rathindranath; Kaur, Harpreet; Yadav, Kamlesh; Haldar, Krishna Kanta
It is essential to design high-efficiency, stable, and inexpensive electrocatalysts for the oxygen evolution reaction (OER). We fabricate a hybrid system of perovskite LaCoO3 with spinel NiCo2O4 denoted LaCoO3/NiCo2O4 via an in situ hydrothermal process. In situ incorporation of LaCoO3 nanoparticles on the NiCo2O4 nanoflower surface is confirmed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images. Benefiting from the interface engineering, the obtained LaCoO3/NiCo2O4 hybrid nanoflowers exhibit the lowest overpotential of 353 at a current density of 10 mA/cm2 and a small Tafel slope of 59 mV/dec in alkaline media compared with pristine LaCoO3 (401 mV, 116 mV/dec) and NiCo2O4 (386 mV, 73 mV/dec). The optimized sample possesses a higher electrochemical surface of 111.45 cm2 than LaCoO3 perovskite (35.37 cm2) and NiCo2O4 spinel oxide (61.37 cm2) structures. The enhanced OER performance of the LaCoO3/NiCo2O4 composite structure is due to the accumulation of LaCoO3 nanoparticles over NiCo2O4 petals, which introduces a substantial number of electrochemically active sites for the catalysis process to promote charge and mass transport. In addition to this, LaCoO3/NiCo2O4 exhibits long-term stability over 20 h. Thus, it is believed that the excellent OER activity of the LaCoO3/NiCo2O4 composite structure is associated with strong interaction between LaCoO3 and NiCo2O4 as well as a large surface area and a unique flower structure. � 2022 American Chemical Society.
Mixed-phase MoS2 nanosheets anchored carbon nanofibers for high energy symmetric supercapacitors
(Elsevier Ltd, 2023-03-14T00:00:00) Kour, Pawanpreet; Deeksha; Kour, Simran; Sharma, A.L.; Yadav, Kamlesh
Mixed-phase MoS2 (MS) nanosheets anchored carbon nanofibers (CNFs) have been synthesized via a hydrothermal route. The concentration of CNFs has been varied in the MS/CNF-x composite (where, x = 1, 1.5, 2, and 3 represents the molar concentration of CNFs) to investigate the impact of CNFs on the electrochemical behavior of the material. The incorporation of CNFs offers a conductive path for the diffusion of ions and provides structural support which limits the restacking of the MoS2 layers during the charging/discharging. The MS/CNF-2 composite delivered superior electrochemical performance compared with the other composites owing to the positive synergy between MoS2 and CNFs. The specific capacitance manifested by MS/CNF-2 (626.08 F g?1 at 1 A g?1) is about four times that of pristine MS (159.35 F g?1). It is also observed that MS/CNF-2 exhibited higher electrochemical stability than pristine MS. Furthermore, the symmetric supercapacitor (SSC) device achieved a tremendous energy density of 42.6 Wh kg?1 at 2.4 kW kg?1. To test its practical applicability, LEDs of different color (red, green, and blue) have been illuminated using a series combination of three symmetric electrode cells. The red, green, and blue LEDs lighted up for 15 mins, 7 mins, and 3 mins. The results demonstrate the superiority of the MS/CNF composite for symmetric supercapacitors. � 2023
MoS2-based core-shell nanostructures: Highly efficient materials for energy storage and conversion applications
(Elsevier Ltd, 2023-04-19T00:00:00) Kour, Pawanpreet; Deeksha; Kour, Simran; Sharma, A.L.; Yadav, Kamlesh
Molybdenum disulfide (MoS2) has acquired immense research recognition for various energy applications. The layered structure of MoS2 offers vast surface area and good exposure to active edge sites, thereby, making it a prominent candidate for lithium-ion batteries (LIBs), supercapacitors (SCs), and hydrogen evolution reactions (HERs). However, the limited conductivity, less number of active sites, and structural instability of MoS2 during continuous electrochemical cycling hinder its applications. In this regard, the formation of core-shell structures has been evolving as a prominent approach to uplift the electrochemical/electrocatalytic activity of MoS2 for energy-based applications. The unique core-shell composites of MoS2 with different electro-active materials exhibit superior electrochemical and electrocatalytic properties on account of the synergy of the core and the shell materials. These materials offer huge active area, high conductivity, an easy pathway for charge diffusion, and stable cyclic life leading to their outstanding electrochemical activity. In this review, various core-shell structures of MoS2 with carbon, metal oxides/sulfides, and conducting polymers are discussed for LIBs, SCs, and HERs. The function of core and shell materials in elevating the electrochemical activity of MoS2 based core-shell composites have been explored in detail. The effect of doping of core and shells on the performance of the composite has also been elucidated. The doped MoS2 based core-shell composites manifest tremendous electrochemical performance compared to the un-doped counterpart. Thus, these unique structured core-shell composites are regarded as futuristic candidates for energy storage and conversion systems. � 2023
Self-assembled carbon wrapped manganese cobaltite nano-composite with promising electrochemical performance for symmetric and asymmetric supercapacitor device
(Elsevier Ltd, 2023-05-27T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.
The growing energy requirements of modern society have led to an intensive search for advanced supercapacitor (SC) electrode materials. Binary transition metal oxides with excellent supercapacitive performance are among the most promising materials. However, the phase transformation of these metal oxides during repeated charging/discharging is a major concern, which depletes their cyclic performance. Coating metal oxides with carbon can provide structural stability to the metal oxide, thereby increasing their cyclic life. In addition, the highly conductive carbon enhances the capacitance of metal oxides by allowing the effective transfer of charges from MnCo2O4 to the current collector. In this study, self-assembled carbon-wrapped MnCo2O4 composite has been prepared through a two-step process involving hydrothermal and solution-mixing processes. The structural/electrochemical performances of the composites have been investigated. The optimized composite offered a maximum capacitance of 626.8 Fg?1 withholding 98 % of capacitance for 6000 cycles. Furthermore, the electrochemical performance of the composite has also been tested in an all-redox symmetric SC (SSC) as well asymmetric (ASC) configuration. In the symmetric cell, 30.2 Whkg?1 of energy is reported for 1.6 kWkg?1 of power. The asymmetric cell with the optimized composite as a cathode and MnO2/Activated carbon as an anode was fabricated. The ASC displayed 45.5 Whkg?1 of energy corresponding to 10 kWkg?1. Three SSCs/ASCs in series illuminated a panel of 39 red-LEDs for 9 and 15 min, respectively. The results suggest the promising performance of such composites for hybrid supercapacitors. Thus, the fabrication of all-redox-type SSCs/ASCs can be a futuristic approach for hybrid storage systems. � 2023 Elsevier Ltd
Synergistic improvement in electrochemical performance of Cr-doped MoS2/CuCo2S4 binary composite for hybrid supercapacitors
(Elsevier Ltd, 2023-10-31T00:00:00) Kour, Pawanpreet; Kour, Simran; Deeksha; Sharma, A.L.; Yadav, Kamlesh
The synergistic effect of transition metal doping and composite formation can be imperative to improve the limited conductivity and inferior cyclic stability of MoS2 for supercapacitors. In this work, firstly, the impact of Cr-doping on the electrochemical activity of MoS2 has been discussed. Afterwards, the optimized Cr-doped MoS2 (CrMS-5) sample has been combined with CuCo2S4 (CCS) to further enhance its charge storage ability and cyclic stability. The CrMS-5/CCS composite delivers tremendous electrochemical activity as an electrode with a specific capacity of approximately 1324.08 C g?1 at 4 A g?1. The outstanding performance of the doped binary composite is on account of the synergism between doping and composite formation that results in increased conductivity and numerous redox active sites for charge storage. Furthermore, a symmetric supercapacitor device (SSC) has been fabricated using a CrMS-5/CCS electrode. It attains a high energy density of 46.63 Wh kg?1 corresponding to 1 kW kg?1 of power and exhibits remarkable cyclic stability of 81% for up to 5,000 cycles. The device illuminates a star-shaped LED panel of 12 red LEDs for 30 min. Thus, the above outcomes demonstrate the superiority of the doped MoS2-based composites for high-energy symmetric supercapacitors. � 2023 Elsevier Ltd
Transition Metal-based Perovskite Oxides: Emerging Electrocatalysts for Oxygen Evolution Reaction
(John Wiley and Sons Inc, 2023-01-23T00:00:00) Deeksha; Kour, Pawanpreet; Ahmed, Imtiaz; Sunny; Sharma, Surender Kumar; Yadav, Kamlesh; Mishra, Yogendra Kumar
Development of clean and sustainable renewable energy sources is imperative to deal with the future energy crises. Various technologies have been developed in this context, for example, water electrolysis, reversible fuel cell and metal-air batteries etc. However, the sluggish kinetics of oxygen evolution reaction (OER) occurring at the anode of these energy storage/conversion systems becomes a significant hurdle. Recently, researchers utilized noble metals as electrocatalysts to enhance their efficiency still the high cost and scarcity of these materials draw the attention of researchers towards the cost-effective Perovskite oxide nanomaterials due to their extraordinary flexibility. In this review, the importance of perovskite oxide nanomaterials as electrocatalysts for OER is discussed, followed by related reaction mechanisms and series of activity descriptors. Fundamental understanding about the instrumentation, parameters and protocols for the experimental measurements including concerned issues are also summarized. Moreover, various activation strategies adopted in recent years to enhance the electrocatalytic performance of perovskite oxides are also underlined. The article concludes with an outlook of existing challenges and future scope of these materials as electrocatalysts. The challenges and prospects discussed herein may pave the ways to rationally design the highly active and stable perovskites to outperform noble metal-based OER electrocatalysts. � 2023 The Authors. ChemCatChem published by Wiley-VCH GmbH.
Tuning the Morphology of Lanthanum Cobaltite Using the Surfactant-Assisted Hydrothermal Approach for Enhancing Oxygen Evolution Catalysis
(Springer Science and Business Media Deutschland GmbH, 2022-09-01T00:00:00) Deeksha; Kour, Pawanpreet; Ahmed, Imtiaz; Haldar, Krishna Kanta; Yadav, Kamlesh
The high consumption rate of fossil fuels to meet the global energy demands attracts the progress of innovative energy storage and conversion systems. Among them, water electrolysis shows major concern because of its great potential to produce clean hydrogen energy. The dawdling dynamics of the oxygen evolution reaction (OER) that occurs on the anode results in the low energy efficiency of the process. Perovskite oxide with transition metal on the B site possesses a high intrinsic as well as extrinsic activity toward OER. However, the low specific surface area restricts their catalytic activity. Here, we report on the synthesis of lanthanum cobaltite (LaCoO3) nanoparticles and bundles of nanorods using glycine and PVP surfactants, respectively, via the hydrothermal method. Structural characterizations confirmed the pure phase synthesis of LaCoO3 perovskite nanomaterials and further their electrocatalytic performance is investigated in an alkaline medium (1 M KOH). The results show that randomly oriented bundles of nanorods (average length 515 nm, average diameter 65 nm) exhibit smaller overpotential (? = 420 mV) at j = 10 mA cm?2 and the Tafel slope (99 mV dec?1) compared with nanoparticles (? = 450 mV and Tafel slope ~ 110 mV dec?1). The dramatically improved OER activity and larger electrochemical surface area (ECSA) of nanorods as compared to nanoparticles are because of the interconnected porous architecture of nanorods. Our work not only highlights the surfactant-assisted hydrothermal approach to synthesize the nanorods but also introduces the effect of a change in morphology on electrochemical activity. � 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.