Browsing by Author "Shachi Tiwari"

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A plausible mechanism in premicellar aggregates for photocurrent generation in photogalvanic cell for simultaneously solar power conversion and storage
(Elsevier Ltd, 2022) Chandrakanta Mall; Shachi Tiwari; Prem Prakash Solanki
Photogalvanic (PG) cells are the only solar cell that can convert and store solar energy simultaneously. The PG cell is based on the diffusion of electrolytes (dye, reductant, alkali/acid and surfactant). We have completed photogalvanic study for the four (BCB-fructose, BCB-AA, MB-fructose and MB-AA) redox systems without and with SDS, CTAB and tween 80 surfactant in our previous research work. The results show that the most efficient system is MB-AA-SDS, in which methylene blue (MB) as a photosensitizer, ascorbic acid (AA) as reductant, and sodium dodecyl sulphate (SDS) as anionic surfactant is used. Since, to make an efficient cell, it is very important to understand the mechanism part. Consequently, the aim of this paper is to provide information about the basic difference of photocurrent generation in PV, DSSC and the PG cell, a plausible mechanism for the generation of electricity in the PG cell having MB, AA and SDS, and also give mechanism for stabilization of MB molecules in premicellar region of SDS on the basis of findings of our previous research work and literature study. For the same, first, made a comparative study for generation of electricity in PV, DSSC and the PG cell, then the most possible mechanism for photocurrent generation in PG cell and lastly mechanism for solubilization and stabilization of the MB molecules by SDS have been given. The comparative study of different solar cells shows that the basic principle for conversion of solar to electrical energy is same for all solar cells. The main difference is in the place of chemical reactions which occur on the surface of the electrode in solar cells while in the PG cells, it occurs inside the electrolytic solution. The AA/ascorbate ion and the base form of the MB are stabilized by premicellar aggregates of SDS, this helps to solubilize the MB molecules by providing an ordered way and enhancing the number of MB molecules for absorption of light in the PG cell. This ultimately enhances the number of leuco forms of MB which leads to an increase in the number of electrons in the external circuit of the PG cell. Thus, by understanding the most plausible mechanism one can make a PG cell in which the compatibility of surfactant is maximum with a dye-reductant system for photocurrent generation and storage, simultaneously. Further, it provides basic ideas about conditions and parameters which are responsible for the better electrical output of the PG cell. This may make the cell practically viable for daily life in the future. © 2022 Elsevier Ltd
A review on biomacromolecular hydrogel classification and its applications
(Elsevier B.V., 2020) Swati Sharma; Shachi Tiwari
Biomacromolecular hydrogels are consist of 3D networks, which have a tendency to absorb large amount of water without dissolving in aqueous medium. Such inherent feature of the hydrogels facilitates the scientific research interest to a dominating path in extending their potential in various fields. In recent years, development of responsive hydrogels has been observed in various field. Self-healing property of the hydrogel attracts more attention in different areas because this property increases the lifespan of the polymeric material. By keeping all these views in mind, the present review focuses on the classification of biomacromolecular hydrogels, methods and its applications. The polymeric material exhibiting multi-responsive properties such as swelling, pH responsive, mechanically strong, self-healing, flexible plays vital role in different applications. In addition, this review summarizes the classification of hydrogels, based on their chemical and physical state along with the various applications. At the end, a brief outlook also presented the future aspects of the hydrogels. © 2020 Elsevier B.V.
CMC studies of CTAB, SLS & tween 80 by spectral and conductivity methodology to explore its potential in photogalvanic cell
(Elsevier B.V., 2020) Shachi Tiwari; Chandrakanta Mall; Prem Prakash Solanki
In the present article, the critical micelle concentration (CMC) of cetyltrimethylammonium bromide (CTAB, cationic), sodium lauryl sulphate (SLS, anionic) and tween 80 (nonionic) surfactants has been studied in the presence and absence of methylene blue (MB) dye via spectral and conductometric studies. The magnitude of CMC value of SLS was decreased in large amount in presence of MB due to the cationic and anionic (electrostatic) interaction, while a little bit decrement was obtained with tween 80 and no remarkable change was obtained with CTAB. Since, both the observed values with conductometric and spectral studies supports each other and also founds that the CMC value of SLS and CTAB with MB dye was almost similar to the reported resultant concentration of SLS and CTAB at which the maximum electrical out put was obtained for diffrent dye-reductant-surfactant systems in photogalvanic cells. Therefore, the surfactant (SLS) whose CMC value is more affected in the presence of cationic dye (MB) may be more useful in the photogalvanic cell with suitable reductant. Hence, with this study, the micellar concentration of surfactants can evaluate and dye-surfactant combination in which CMC of surfactant is more affected in presence of dye can be utilized to enhance the overall electrical performance of the photogalvanic cells. © 2020 Elsevier B.V.
Comparison of dye (oxazine and thiazine) materials as a photosensitizer for use in photogalvanic cells based on molecular interaction with sodium dodecyl sulphate by spectral study
(Elsevier B.V., 2019) Chandrakanta Mall; Shachi Tiwari; Prem Prakash Solanki
The photochemistry of dye is playing a significant role for understanding the mechanism of electron transfer reactions in photoelectrochemical devices such as photogalvanic cells, DSSC, semiconductor photo-catalysis, photoconductors, etc. Oxazines (Brilliant Cresyl Blue and Nile Blue O) and thiazines (Azur A, Azur B, Azur C, Methylene Blue and Toluidine Blue O) dyes have been used widely as a photosensitizer with and without surfactants in the photogalvanic cells for solar power conversion and storage. Since, the stability and solubility of photosensitizers (dyes) are increased in the presence of surfactant and these properties lead to enhance the electrical output of the photogalvanic cells. Therefore, here we have studied the extent of interaction of different dyes with sodium dodecyl sulphate (SDS), find out the order of stability of dye–SDS on the basis of magnitudes of shifting in λmax of dye monomer and try to correlate order of dye–SDS interaction with already reported electrical output data of photogalvanic cells. Brilliant Cresyl Blue, Nile Blue O, Azur A and TB O have shown red shifting while Azur B, Azur C and MB have shown blue shifting in their λmax value with SDS, which indicates formation of dye–surfactant complex. But, the extent of formation of complex for different dyes with SDS was different due to change in their alkyl groups. Dyes with red shifting have greater stability in excited state as well as higher electrical output data of the cell than dye with blue shifting. On the basis of both red and blue shifting, order of stability of dyes–SDS complex was found as: Brilliant Cresyl Blue > Toluidine Blue O > Azur A > Nile Blue > Azur B > Methylene Blue > Azur C. The order of electrical output values of these dyes in photogalvanic cells have also been supported by literature data in the presence of SDS. Hence, the dye–surfactant complex which would have greater stability in excited state might be more useful for improvement of conversion efficiency and storage capacity of photogalvanic cells in the future. © 2018 King Saud University
Correlation between Photoelectrochemical and Spectrophotometric Study of Dye-Surfactant Combination in Photogalvanic Cell
(Pleiades Publishing, 2019) Chandrakanta Mall; Shachi Tiwari; Prem Prakash Solanki
Abstract: The photogalvanic cells are rechargeable device with the sun light in which surfactant solutions are potentially important for efficient energy conversion and storage. Here, effect of cationic cetyltrimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulphate (SDS) and non ionic tween 80 surfactants on the electrical output of the cationic oxazine dye brilliant cresyl blue (BCB)-fructose (redox couple) system in photogalvanic cells have been studied. For this, the photopotential and photocurrent for different cells having BCB-fructose system without and with surfactant (CTAB, SDS and tween 80) in the alkaline medium have been measured. The total 30 different cells have been prepared for optimizing the concentration of electrolytes corresponding to the higher electrical out put. Generally, the electrical output increases in presence of a particular surfactant, due to increase in solubilization and stabilization properties of dye molecules in the water. The amount of enhancement in electrical output of BCB-fructose system was highest with SDS and lowest with tween 80, i.e. the order for BCB-fructose system with different surfactants in photogalvanic cells is: BCB-fructose-SDS > BCB-fructose-CTAB > BCB-fructose-tween 80. This order for electrical output was good agreement with the stability order of BCB-SDS/CTAB/tween 80 system, on the basis of spectrophotometric study. Hence, among these surfactants, SDS has stronger capacity, (due to opposite charge on BCB and SDS) to stabilize the BCB-fructose system leads to enhancement in electrical output of photogalvanic cells. Therefore, dye and surfactant, having chemical structure, like BCB and SDS, has a great importance of improvement of electrical performance to photogalvanic cells in the future. © 2019, Allerton Press, Inc.
Dynamic imine bond based chitosan smart hydrogel with magnified mechanical strength for controlled drug delivery
(Elsevier B.V., 2020) Swati Sharma; Pallavi Jain; Shachi Tiwari
Hydrogel finds an interesting candidate in the biomedical field due to their unique properties such as biocompatibility, biodegradability, soft as tissue etc. In the reported research article natural biopolymer i.e. chitosan based hydrogel was developed via condensation reaction with cuminaldehyde. Chitosan and cuminaldehyde were used for the gel formation by covalent bonding between free amino group and carbonyl group of chitosan & cuminaldehyde respectively. A series of hydrogel has been developed by taking different concentration of cuminaldehyde (6-10 mmol). Chemical structure of the synthesized hydrogel was further confirmed by FTIR. The surface morphology of the synthesized hydrogel was confirmed from the scanning electron microscopy (SEM). Prepared hydrogel was swelled very fast similar to the super-porous hydrogel along with rapid self-healing property which is confirmed by rheology statistics. Mechanical strength of the hydrogel was investigated from the rheology analysis and demonstrates good mechanical properties i.e. storage modulus (G') found to 107 pa. Further, the sustained release of hydrophilic drug i.e. levofloxacin from the hydrogel matrix at different pH range 6–7 has been carried out. Hydrogel with maximum cuminaldehyde amount releases max drug i.e. 96% while hydrogel with 6 mmol shows minimum drug release i.e.54%. Hydrogel shows controlled release of levofloxacin up to 90 h. The present research work revealed that produced hydrogel will become a promising candidate in biomedical field. © 2020
Evaluation of mixed dye combination by spectral study for the application as photosensitizer in photogalvanic cells for solar energy conversion and storage
(Elsevier B.V., 2022) Shachi Tiwari; Chandrakanta Mall; Prem Prakash Solanki
The mixed dye combination has significant capacity to absorb broad portion of solar spectrum, which enhance the performance of the photogalvanic cell. Therefore, in present work, all possible (55) combinations of binary mixed dyes of different 11 dyes have been studied, in order to select stable mixed dye combination that can absorb wider range of solar spectrum and retains λmax value of both dyes. Out of all these mixed dyes combinations, MB+BCP absorbs broadest visible wavelength (431.0–664.0 nm) followed by AB+BCP (431.0–645.0 nm), TB+BCP (431.0–628.0 nm) and lowest by BCB+BCP (431.0–625.0 nm). The MB+BCP absorbs the widest visible solar spectrum and retain λmax value of both dyes. The absorbance maxima of these dyes, in mixed dye solution, show no change in their λmax values. It may be because of chemically, MB and BCP both are very stable in nature. Thus, this type of stable mixed dyes combination of photosensitizer may selected as an efficient and broader visible radiation absorbing combination which may enhance the performance of the photogalvanic cell. The broad solar spectrum absorbing mixed dye combination, obtained from present study may offer a promising alternative to the existing dye (randomly selected) as an efficient photosensitizer of the photogalvanic cell for solar energy conversion and storage. © 2021 Elsevier B.V.
Evaluation of most efficient redox couple based on compatibility of donor–acceptor in photogalvanic cell for simultaneous solar power conversion and storage
(Elsevier B.V., 2022) Chandrakanta Mall; Shachi Tiwari; Prem Prakash Solanki
There are several devices for direct conversion of solar energy to electric energy, but, all have zero storage capacity. Photogalvanic cell (PG) has both properties to convert and store (chemical form) the solar energy. Therefore, the PG cells may be playing a very important role to fulfill energy demand in the future. Here, our aim is to evaluate the most efficient redox (dye-reductant combination) couple based on the compatibility of the dnor (reductant) and acceptor (dye) species for the PG cell. For this, we have completed photogalvanics (measurement and calculation of different electrical parameters of each cell) for brilliant cresyl blue (BCB) or methylene blue (MB)-fructose/ascorbic acid (AA) redox couple for solar power conversion and storage. Here, MB/BCB and fructose/AA have been used as photosensitizers and reductants, respectively. Results show the order for redox couple based on electrical output is: MB-AA > MB-fructose > BCB-AA > BCB-fructose. The electrical output is high when MB is used as a photosensitizer with both fructose and AA. It may be because of the larger λmax and the low molecular weight of MB than BCB. Indeed, the generation of electricity in the PG cell is the outcome of the diffusion process of molecules or ions in an electrolytic solution. The results reported in the literature for the different dye-AA systems of the PG cells clearly indicate that the electrical output of every system has a lower value as compared to the MB-AA redox couple of present study. Hence, MB-AA is the most efficient and stable system out of the four redox couples. Thus, the dye and reductant having structures like MB and AA are more compatible for electron acceptor and donor power for simultaneous solar power conversion and storage in the PG cell. © 2022 Elsevier B.V.
Retraction notice to “A review on biomacromolecular hydrogel classification and its applications” [ Int. J. Biol. Macromol. 162 (2020) 737-747, (S0141813020335492), (10.1016/j.ijbiomac.2020.06.110)]
(Elsevier B.V., 2023) Swati Sharma; Shachi Tiwari
Retraction notice. This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and Author. The work included substantial parts copied without attribution from a prior work by Varaprasad et al. (2017): https://doi.org/10.1016/j.msec.2017.05.096 © 2023 Elsevier B.V.
Studies of binding of oxazine and thiazine dyes with cetyltrimethylammonium bromide and tween 80 surfactant spectrophotometrically for the photogalvanic cell for solar energy conversion and storage
(Elsevier B.V., 2021) Chandrakanta Mall; Shachi Tiwari; Prem Prakash Solanki
The spectral study of binding of oxazine (NB) and thiazine (AA, AB, AC, MB and TB O) dyes with cationic cetyltrimethylammonium bromide (CTAB) and non ionic tween 80, surfactant has been done in alkaline medium at lab temperature. All dyes show blue shifting in their λmax value in presence of both CTAB and tween 80 but high absorbance with CTAB. Since, the dye which shows less blue shifting in its λmax and more absorbance value with CTAB/tween 80 is considered more stable. Therefore, the dyes MB, TB O and AA (less blue shifting) are more stable than AB, AC and NB (more blue shifting) in presence of CTAB/tween 80. It means the dyes may be more solubilized and stabilized with CTAB than tween 80 and the stability of dye-CTAB/tween 80 is directly proportional to the electrical output in photogalvanic cells. The order of stability of these dyes on the basis of blue shifting with CTAB/tween 80 is: MB > AA > TB O > AB > AC > NB. Hence, this type of study may be helpful for choosing a stable dye-surfactant combination and to understand the reason for stability and higher electrical output of the photogalvanic cell for solar energy conversion and storage. © 2021