Browsing by Author "Meena, M.L."

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Molecular surface-dependent light harvesting and photo charge separation in plant-derived carbon quantum dots for visible-light-driven OH radical generation for remediation of aromatic hydrocarbon pollutants and real wastewater
(Academic Press Inc., 2024) Meena, S.; Sethi, M.; Saini, S.; Kumar, K.; Saini, P.; Meena, S.; Kashyap, S.; Yadav, M.; Meena, M.L.; Dandia, A.; Nirmal, N.K.; Parewa, V.
Despite the growing emphasis on eco-friendly nanomaterials as energy harvesters, scientists are actively searching for metal-free photocatalysts to be used in environmental remediation strategies. Developing renewable resource-based carbon quantum dots (CQDs) as the sole photocatalyst to harvest visible light for efficient pollutant degradation is crucial yet challenging, particularly for addressing the escalating issue of water deterioration. Moreover, the photocatalytic decomposition of H2O2 under visible light irradiation remains an arduous task. Based on this, we designed two types of CQDs, C-CQDs (carboxylic-rich) and A-CQDs (amine-rich) with distinct molecular surfaces. Owing to the higher amount of upward band bending induced by amine-rich molecular surface, A-CQDs efficiently harvest the visible light and prevent recombination kinetics resulting in prolonged lifetimes (25 ps), and augmented charge carrier density (35.7 × 1018) of photoexcited charge carriers. A-CQDs enabled rapid visible-light-driven photolysis of H2O2 (k = 0.058 min−1) and produced higher quantity of •OH radicals (0.158 μmol/sec) for the mineralization of petroleum waste, BETX (i.e. Benzene, Ethylbenzene, Toluene and Xylene) (k = 0.017–0.026 min−1) and real textile wastewater (k = 0.026 min−1). To assess comparative toxicities of both remediated and non-remediated real wastewater samples in a time and dose depended manner, Drosophila melanogaster was used as a model organism. The findings unequivocally demonstrate the potential of remediated wastewater for watering urban forestry. © 2024 Elsevier Inc.
Probing the luminescence behavior of Dy3+/Eu3+ co-doped gadolinium molybdate phosphors under the impact of swift heavy ions
(Springer, 2024) Dutta, S.; Som, S.; Meena, M.L.; Sharma, S.K.
This study delves into the impact of lithium (Li3+) and silver (Ag7+) ion irradiation on the structure and luminescence of Dy3+ doped and Dy3+/Eu3+ co-doped Gd2MoO6 phosphors, synthesized via the hydrothermal method. To explore the influence of ions with varied mass and energy, 30 MeV Li3+ and 100 MeV Ag7+ ions were employed at different fluences. We elucidate the induced effects based on defect formation and the role of these ions’ linear energy transfer (LET) within the irradiated material. SRIM software estimates the depth profile of the ions. Irradiation of the Gd2MoO6 phosphors with Li3+ and Ag7+ ions resulted in the formation of disordered lattices or tracks, modifying their structural, optical, and luminescence properties, which were analyzed by various techniques, including X-ray diffraction, scanning electron microscopy, diffuse reflectance, and photoluminescence. Thermoluminescence (TL) tests and calculations of trapping parameters were conducted to evaluate the dosimetric potential. The findings reveal a more pronounced effect of silver ions compared to lithium ions on the structural and luminescence behavior of doped and codoped Gd2MoO6 phosphors due to their higher atomic weight. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Tuning Surface Energy of Pristine Separator with γ-AlO(OH) Nanocapsules for Inhibiting Lithium Polysulfide Shuttle and Lithium Dendrite Growth
(American Chemical Society, 2024) Abbas, S.A.; Ali, M.; Hakeem, A.S.; Saeed Alzahrani, A.S.; Meena, M.L.; Javid, M.
The severe shuttling of dissolved lithium polysulfides (LiPSs) (Li2Sx, 4 ≤ x ≤ 8) and the generation of lithium dendrites upon cycling have hampered the safety and performance of lithium-sulfur batteries (LSB). Herein, we report the strategy of tuning the surface energy of the pristine separator with γ-AlO(OH) nanocapsules to address the aforementioned problems. The enhanced surface energy from 26.62 to 63.64 mJ m-2 yields multiple benefits, including impeding the migrating polysulfides by chemically binding them with γ-AlO(OH) nanocapsules, enhancing the lithium-ion migration through the separator by promoting hydrophilicity in the separator and mitigating the generation of lithium dendrites by a uniform distribution of Li+ on top of lithium metal via interaction with γ-AlO(OH) nanocapsules. Live discharging of the H-cell demonstrated that the LiPS mitigation can be curtailed by using γ-AlO(OH) nanocapsules modified separator (BNC). Moreover, the BNC separator’s thermally insulating properties render the Li-S battery stable behavior while cycling at an even temperature of 75 °C. The spray coating technology used for coating γ-AlO(OH) nanocapsules on top of pristine separator offers a scalable solution for commercializing such modified separators. © 2024 American Chemical Society.
Visible-light induced effective and sustainable remediation of nitro organics pollutants using Pd-doped ZnO nanocatalyst
(Nature Research, 2024) Vikal, S.; Meena, S.; Gautam, Y.K.; Kumar, A.; Sethi, M.; Meena, S.; Gautam, D.; Singh, B.P.; Agarwal, P.C.; Meena, M.L.; Parewa, V.
Nitroaromatic compounds represent a class of highly toxic pollutants discharged into aquatic environments by various industrial activities, posing significant threats to ecological integrity and human health due to their persistent and hazardous nature. In this study, Pd-doped ZnO nanoparticles were investigated as a potential solution for the degradation of nitro organics, offering heightened photocatalytic efficacy and prolonged stability. The synthesis of Pd-doped ZnO NPs was achieved via the hydrothermal method, with subsequent analysis through XRD spectra and XPS confirming successful Pd doping within the ZnO matrix. Characterization through FESEM and HRTEM unveiled the heterogeneous morphologies of both undoped and Pd-doped ZnO nanoparticles. Additionally, UV–vis and PL spectroscopy provided insights into the optical properties, chemical bonding, and defect structures of the synthesized Pd-doped ZnO NPs. Pd doping induces a redshift in ZnO’s absorption spectra, reducing the bandgap from 3.12 to 2.94 eV as Pd concentration rises from 0 to 0.2 wt.%. The photocatalytic degradation, following pseudo-first-order kinetics, achieved 90% nitrobenzene abatement (200 µg/L, pH 7) under visible light within 320 min with a catalyst loading of 16 µg/mL. The photocatalytic efficacy of 0.08 wt% Pd-doped ZnO (k = 0.058 min?1) exhibited a 25-fold enhancement compared to bare ZnO (k = 3.1 × 10–4 min-1). Subsequent quenching and ESR experiments identified hydroxyl radicals (OH•) as the predominant active species in the degradation mechanism. Mass spectrometry analysis unveiled potential breakdown intermediates, illuminating a plausible degradation pathway. The investigated Pd-doped ZnO nanoparticles demonstrated reusability for up to five successive treatment cycles, offering a sustainable solution to nitro organics contamination challenges. © The Author(s) 2024.