Browsing by Author "Subhajit Jana"

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A fluorescent Ce-EDTA probe for the sensing of ascorbic acid and lysine in real samples
(Royal Society of Chemistry, 2022) None Rajpal; Ashish Kumar; Subhajit Jana; Priya Singh; Rajiv Prakash
In the present work, a fluorescent probe based on an aqueous dispersion of coordination complex Ce-EDTA is utilized for sensing carboxyl compounds. Ce-EDTA is synthesized herein by a hydrothermal method with the help of stoichiometric ratios of cerium (Ce) (+iii) salts and green ligand ethylenediamine N,N,N,N tetra-acetic acid (EDTA). In Ce-EDTA, the Ce ion is surrounded by hexadentate EDTA and three labile aqua ligands, evidenced by FT-IR, XPS, and UV-visible spectroscopy. It exists in the form of polygonal microplates, as apparent by SEM. The sensing mechanism is proposed by choosing carboxyl groups as a part of the ring and open chain. Under the optimized situations, the fluorescence intensities of Ce-EDTA are monitored towards various concentrations of l-lysine (Lys) and ascorbic acid (AA) in these regards. They exhibit a linear response from 20.29 μM to 251.74 μM and 5.62 μM to 60.87 μM with a linear correlation coefficient (R2) of 0.98 and 0.99, respectively. The lower limit of detection is observed as 3.6 μM in the case of Lys and 2.04 μM in the case of AA. The as-prepared probe exhibits suitability for selectivity of AA and Lys in the presence of various interfering agents as well as in real samples for the detection of AA in orange and Lys in soybean seed. © 2022 RSC.
Engineered Ni–Fe prussian blue analogue nanocubes and their transformation into nanocages and mixed oxide for applications as bifunctional electrocatalyst
(Elsevier Ltd, 2024) Shweta Pal; Subhajit Jana; Devesh Kumar Singh; Vellaichamy Ganesan; Uday Pratap Azad; Rajiv Prakash
3D nanostructured Prussian blue analogues (PBA) are promising candidates in the family of metal-organic frameworks (MOFs) for applications as bifunctional electrocatalysts due to their open framework structures, high specific surface areas and variable metal active sites. Due to their facile synthesis approach and unique framework structures, these nanostructures can be easily transformed into different structures/materials having different compositions. Herein, we have synthesized Ni–Fe Prussian blue analogue nanocubes (NiFe-PBA-NC) via a simple precipitation method and converted them into Ni–Fe Prussian blue analogue nanocages (NiFe-PBA-NG) and porous mixed metal oxide (NiFe-oxide). For the conversion of nanocubes to nanocages a very controlled etching process is carried out by using an ammonia solution while for the formation of porous mixed metal oxide, nanocubes are annealed in the presence of air. The transformation of nanocubes to nanocages and mixed metal-oxide is thoroughly characterized by various spectroscopic and microscopic techniques and employed as a bifunctional electrocatalyst for oxygen evolution and oxygen reduction reactions (OER and ORR, respectively) in which NiFe-oxide proved to be the best bifunctional catalyst. This thorough and systematic study reveals the fundamentals of the structure-property co-relation towards engineering novel bifunctional electrocatalysts. © 2023 Hydrogen Energy Publications LLC
Evolution of Edge-On Oriented Polymer Films Self-Assembled at the Air-Liquid Interface for High-Performance Electronic Device Applications
(American Chemical Society, 2022) Subhajit Jana; Rajiv Kumar Pandey; Rajiv Prakash
In the context of semicrystal growth in thin films of organic semiconducting polymers (OSPs) at the air-liquid interface, polymer self-assembly is mainly governed by convective Marangoni flow, compressive viscous force, divergent evaporation flux, and high conformational degrees of freedom of OSPs, which lead to a very complex microstructure having many cumulative and noncumulative disorders. In this regard, first time, major polythiophene derivatives such as poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(3,3‴-didodecyl[2,2′:5′,2″:5′′,2′′′-quaterthiophene]-5,5′′′-diyl) (PQT), and poly[2,5-bis (3- tetradecylthiophen-2-yl) thieno[3,2-b]thiophene] (PBTTT) are collectively employed as model OSPs to explain film growth on aqueous substrates and examined using multiple characterization techniques. At first, we have investigated the degree of paracrystalline disorder along (h00) direction in three different polymer backbone structures. Then, the local in-plane orientation of the polymer chains in crystalline domains along the π-πstacking direction has been studied using the bright field HR-TEM images. Moreover, quantum mechanical penetration of localized trap states into the bandgap induced by those structural imperfections has also been quantified from optical property measurements. Finally, we have studied the charge transport properties in all three directions (out-of-plane and in-plane viz. along and across the polymer chains) of the thin solid polymeric films using vertical and planar device architectures. We have observed maximum out-of-plane mobility (μh) 3.7 × 10-5cm2/V·s for P3HT, and in-plane mobility, μh(along the polymer chains) 0.234 cm2/V·s for PBTTT. By considering the obtained results from different characterizations and all possible flow processes, we have tried to propose the exact growth mechanism of these thin films. Thus, our findings give an insight into the fundamentals of polymer self-assembly to a structure-property correlation, which is extremely important for material processing and device engineering to meet the growing technological appeal. © 2022 American Chemical Society.