Browsing by Author "Sharma, Surender Kumar"

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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.
The Curie temperature: a key playmaker in self-regulated temperature hyperthermia
(Royal Society of Chemistry, 2023-11-13T00:00:00) Niraula, Gopal; Wu, Chengwei; Yu, Xiaogang; Malik, Sonia; Verma, Dalip Singh; Yang, Rengpeng; Zhao, Boxiong; Ding, Shuaiwen; Zhang, Wei; Sharma, Surender Kumar
The Curie temperature is an important thermo-characteristic of magnetic materials, which causes a phase transition from ferromagnetic to paramagnetic by changing the spontaneous re-arrangement of their spins (intrinsic magnetic mechanism) due to an increase in temperature. The self-control-temperature (SCT) leads to the conversion of ferro/ferrimagnetic materials to paramagnetic materials, which can extend the temperature-based applications of these materials from industrial nanotechnology to the biomedical field. In this case, magnetic induction hyperthermia (MIH) with self-control-temperature has been proposed as a physical thermo-therapeutic method for killing cancer tumors in a biologically safe environment. Specifically, the thermal source of MIH is magnetic nanoparticles (MNPs), and thus their biocompatibility and Curie temperature are two important properties, where the former is required for their clinical application, while the latter acts as a switch to automatically control the temperature of MIH. In this review, we focus on the Curie temperature of magnetic materials and provide a complete overview beginning with basic magnetism and its inevitable relation with Curie's law, theoretical prediction and experimental measurement of the Curie temperature. Furthermore, we discuss the significance, evolution from different types of alloys to ferrites and impact of the shape, size, and concentration of particles on the Curie temperature considering the proposed SCT-based MIH together with their biocompatibility. Also, we highlight the thermal efficiency of MNPs in destroying tumor cells and the significance of a low Curie temperature. Finally, the challenges, concluding remarks, and future perspectives in promoting self-control-temperature based MIH to clinical application are discussed. � 2023 The Royal Society of Chemistry.
Facile synthesis of Bi2WO6/rGO nanocomposites for photocatalytic and solar cell applications
(Elsevier Ltd, 2021-02-22T00:00:00) Shad, Naveed Akhtar; Sajid, Muhammad Munir; Afzal, Amir Muhammad; Amin, Nasir; Javed, Yasir; Hassan, Safia; Imran, Zahid; Razaq, Aamir; Yousaf, Muhammad Imran; Munawar, Anam; Sharma, Surender Kumar
Manipulation of materials at nanoscale provides many new and enhanced properties to be utilized for multifaceted applications, which was not possible before. In this study, we fabricated Bi2WO6/rGO composites using hydrothermal method. The obtained composites were then examined using different analytical techniques such as XRD, SEM, TEM, FTIR, XPS, BET, and AFM. Their catalytic properties were assayed by carrying out the degradation of organic dye Rhodamine B (RhB) and employed as a hole transport layer (HTL) in the perovskite solar cells. The fabricated nanocomposites were able to degrade 98% of dye solution within 4 h. The improved photocatalysis is attributed to a large surface area ~86.06 m2/g with pore size 7.812 nm and enhanced separation of electron-hole pair charges due to rGO sheets. The open-circuit voltage was increased up to 0.94 V when composite materials were used as HTL. The power conversion efficiency (PCE) of the device was enhanced to 11% because of the improvement in the interface quality between HTL and the perovskite layer. It is conceived that the fabricated nanomaterial may show excellent potential in smart solar cell applications. � 2021 Elsevier Ltd and Techna Group S.r.l.
Modern Luminescence from Fundamental Concepts to Materials and Applications: Volume 1: Concepts of Luminescence
(Elsevier, 2023-01-27T00:00:00) Sharma, Surender Kumar; da Silva, Carlos Jacinto; Garcia, Daniel Jaque; Shrivastava, Navadeep
Modern Luminescence: From Fundamental Concepts to Materials and Applications, Volume One, Concepts and Luminescence is a multivolume work that reviews the fundamental principles, properties and applications of luminescent materials. Topics addressed include key concepts of luminescence, with a focus on important characterization techniques to understand a wide category of luminescent materials. The most relevant luminescent materials, such as transition metals, rare-earth materials, actinide-based materials, and organic materials are discussed, along with emerging applications of luminescent materials in biomedicine, solid state devices, and the development of hybrid materials. This book is an important introduction to the underlying scientific concepts needed to understand luminescence, such as atomic and molecular physics and chemistry. Other topics explored cover the latest advances in materials characterization methods, such as Raman spectroscopy, ultrafast spectroscopy, nonlinear spectroscopy, and more. Finally, there is a focus on the materials physics of nanophotonics. � 2023 Elsevier Ltd. All rights reserved.
Predominated capacitive behavior of Ag-doped magnesium vanadate as a novel electrode material for supercapacitors
(Elsevier Ltd, 2023-06-11T00:00:00) Umair, Muhammad; Shad, Naveed Akhtar; Hussain, S.; Jilani, Asim; Sajid, Muhammad Munir; Arshad, Muhammad Imran; Hasnain Rana, Hafiz Talha; Sharma, Surender Kumar; Mishra, Yogendra Kumar; Javed, Yasir
Transition metal vanadate nanostructures are getting significant importance as an efficient electrode material for modern energy storage applications. In this work, a simple hydrothermal method is employed for the synthesis of magnesium vanadate (MgV2O5) and Ag-doped magnesium vanadate (Ag doped MgV3O8) nanomaterials. The X-ray diffraction (XRD) analysis reveals the formation of an orthorhombic structure for magnesium vanadate, whereas the Ag-doped magnesium vanadate results in a monoclinic structure. Interestingly, the optical bandgap is observed to increase from 2.85 eV to 3.92 eV with the increase in Ag-doping as revealed from Tauc's plot of the UV-visible absorption spectrum. The electrochemical performance of magnesium vanadate electrodes is thoroughly investigated by cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy. The Ag-doped magnesium vanadate shows higher specific capacitance (Cs = 706 Fg?1) in comparison to undoped (325 Fg?1) at a current density J = 5 Ag?1. The theoretical investigations through Dunn's model demonstrate a major contribution arises from surface-controlled processes, which increase as high as 91% at scan rate of 60 mVsec?1. Our findings indicate that Ag-doping significantly improves the overall electrochemical response of magnesium vanadate as an efficient electrode material for supercapacitor applications. � 2023 Hydrogen Energy Publications LLC
Probing the optical and magnetic modality of multi core-shell Fe3O4@SiO2@?-NaGdF4:RE3+ (RE = Ce, Tb, Dy) nanoparticles
(Elsevier B.V., 2023-02-22T00:00:00) Shrivastava, Navadeep; Ospina, Carlos; Jacinto, Carlos; de Menezes, Alan S.; Muraca, Diego; Javed, Yasir; Knobel, Marcelo; Luo, Zhiping; Sharma, Surender Kumar
A robust yellowish-green emitting multi core-shell Fe3O4@SiO2@?-NaGdF4:RE3+ (RE = 5% Ce, 5% Tb, x% Dy; x = 1, 5 and 10 mol.%) nanoparticles (NPs) containing both magnetic and luminescence modalities, are synthesized using simple, fast and efficient microwave-assisted hydrothermal method. The Rietveld analysis of X-ray diffraction and high-resolution transmission electron microscopy provides an average crystallite size of ?30 nm, confirming the successful coating of the ?-NaGdF4 hexagonal phase over Fe3O4. The detailed photoluminescence investigation suggests a down-converting energy transfer process, Ce3+?Gd3+?Tb3+? Dy3+ in which Gd3+ ions play a significant intermediate role assisted by Tb3+. The excitation spectra consist of dominant broadband at ?252 nm due to Ce3+ (4f�5d), two sharp lines at ? 271 nm, and ?311 due to Gd3+ (8S7/2?6IJ and 6PJ), and frail f?f transitions due to Tb3+ and Dy3+ ions. The excitation at ?252 nm fetches weak and sharp emission of Gd3+ ions at 310 nm, weak broad emission of Ce3+ (300�400 nm), and strong emission color lines of RE3+ (400�700 nm) due to characteristic transitions of Tb3+ (5D4?7FJ, J = 6�3), and Dy3+ (4F9/2�6H15/2, 6H13/2), respectively. The quenching phenomenon is observed due to concentration, and back transfer energy is proposed. The magnetic hysteresis loops display superparamagnetic behavior at 300 K and ferromagnetic ordering at 2 K with a remarkable difference in their magnetization values and confirming the blocking temperatures around physiological temperature ranges. The magneto-luminescence characteristics of the bifunctional system can be easily manipulated under an external magnetic field and suggest an efficient candidate for hybrid medical imaging such as MRI plus X-ray imaging and radiation detection. � 2023 Elsevier B.V.
Scopes of laser in spectroscopy
(Elsevier, 2023-01-27T00:00:00) Verma, Dalip Singh; Shrivastava, Navadeep; Sharma, Surender Kumar
Spectroscopy deals with the interaction of light radiation with matter, which provides information on the structure and properties of matter (solids, liquids, and gasses). If laser light is used in place of the light radiation, then the spectroscopy is known as laser spectroscopy. Laser spectroscopy has emerged as a tool in many scientific techniques like tracking air quality, process control, medical research, national security, agriculture, artwork authentication, and many more. This is due to the special characteristics of lasers as compared to ordinary light. Although the emission of laser radiation is governed by the same rules and principles as that of any other light sources, laser light is not like any other ordinary source of radiation found in nature. It is a much more powerful technological tool than light from ordinary sources. Its features like coherence, monochromaticity, and collimation (directionality or low-beam divergence) make it special. The laser beam emerging from the output mirror of the resonant cavity is highly parallel, and its divergence (the spread in a beam of light) is typically a few milliradians, that is, negligibly small. The photons emitted even at a slight angle with respect to the tube axis bounce back into the walls of the tube and do not contribute to the output beam (not 100% true due to diffraction). The laser cavity is resonant only for the frequencies ?=nc/2d, where d is the separation between the mirrors of the resonant cavity adjusted as an integral of half of the wavelength, limiting the wavelength range (production of laser of well-defined wavelength). The intensity of the laser, defined as the power emitted per unit area of the output mirror per unit solid angle, is extremely high compared with that of a conventional source. The conventional sources of radiation are incoherent in nature, which means that any two photons of the electromagnetic waves of the same wavelength are out of phase, while the laser is both temporally and spatially coherent, which means that the coherence of the laser medium exists for a relatively long time and over a relatively large distance. Laser, by virtue of its coherent nature, is used for local heating, as in metal cutting, metal welding, and for holography. The coherent nature of the laser is by virtue of the mechanism through which it is produced, that is, the process of stimulated emission where photons are essentially copied or exactly in phase. The production of laser in the same phase takes place as all emitted photons are at exactly the same wavelength due to the transition between two fixed energy levels (the amplification mechanism of the laser). The simplest explanation for these properties of the laser is in the mechanism of the laser itself. The process mainly includes the stimulated emission, which takes place in the amplifying medium contained by the laser. This is done with the application of a set of mirrors used for feeding the light back to the amplifying medium so that the developed beam is grown continuously. The key concept for the realization of the laser operation is the principle of coherence accompanying stimulated emission. This stimulated emission needs the process of population inversion, for which the lasing medium must have at least three energy levels. � 2023 Elsevier Ltd. All rights reserved.
Strain-mediated magnetoelectricity probed by Raman spectroscopy in h-ErMn O3
(American Physical Society, 2023-07-05T00:00:00) Correa, A.; Barbosa, D.A.B.; De Menezes, A.S.; Valente-Rodrigues, C.L.; Sharma, Surender Kumar; Santos, C.C.
We show the role of strain in magnetoelectric effect through coupling between order parameters and their interplay using infrared/Raman-active optical phonons in hexagonal manganite (h-ErMnO3). The magnetoelectric coupling is arbitrated through strain from infrared-active phonons, which by symmetry are also Raman active. The identification of the primitive order parameters by spin-phonon coupling opens a promising avenue to realize the strategy based on coupling of spins, optical phonons, and strain to create magnetoelectrics with strain-mediated interaction through spin-lattice coupling in bulk inducing a ferromagnetic-ferroelectric state in an antiferromagnetic-paraelectric phase. � 2023 American Physical Society.
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.