Debajyoti Mahanta | Gauhati University (original) (raw)

Papers by Debajyoti Mahanta

Journal of Solid State Chemistry, Oct 1, 2007

Heterogeneous conducting polymer composites (organic/inorganic) have been attracting attention ow... more Heterogeneous conducting polymer composites (organic/inorganic) have been attracting attention owing to their applications in various fields [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15] and [16] such as charge storage materials, catalysts, solar cells [8], [9] and ...

Physical Chemistry Chemical Physics

The K+ ion electrochemistry of graphite in aqueous batteries is illustrated.

Materials Today Communications

Journal of Energy Storage

Journal of Energy Storage

ACS Omega, 2021

This study proposes the development of an electrochemical sensor based on fabrication of a glassy... more This study proposes the development of an electrochemical sensor based on fabrication of a glassy carbon electrode (GCE) with Fe 3 O 4-polyaniline (Fe 3 O 4-PANI) nanocomposite, which was further used for enzyme-less detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous medium. Spectroscopic studies, microstructural studies, and elemental analysis established the formation of Fe 3 O 4 nanoparticles with polyaniline coating. The fabricated Fe 3 O 4-PANI-GCE was characterized by electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical response of 2,4-D on Fe 3 O 4-PANI-GCE was evaluated by performing cyclic voltammetry and amperometry experiments. The synergistic effect of the composite causes the superior electrochemical behavior of Fe 3 O 4-PANI-GCE toward the detection of 2,4-D. Amperometric measurements exhibited a linear concentration range from 1.35 to 2.7 μM. The sensitivity and detection limit were evaluated from the amperometric responses, which were found to be 4.62 × 10 −7 μA μM −1 cm −2 and 0.21 μM, respectively. The electrochemical sensing response could be attributed to adsorption of 2,4-D onto the Fe 3 O 4-PANImodified GCE (Fe 3 O 4-PANI-GCE) surface. Fe 3 O 4-PANI-GCE is found to be a simple, low-cost, and biocompatible non-enzymatic sensor for detection of 2,4-D in aqueous medium at ambient temperature.

Journal of Porous Materials, 2014

A new porous carbon with high surface area of 1,313.41 m2 g−1 with pore volume 1.359 cm3 g−1 has ... more A new porous carbon with high surface area of 1,313.41 m2 g−1 with pore volume 1.359 cm3 g−1 has been synthesized from matured tea leaves by chemical activation method using phosphoric acid. The carbon was found to be highly efficient for removal of Cr(VI) from aqueous solution. The effects of various parameters such as contact time, initial metal ion concentration, pH, temperature and amount of adsorbent on the extent of adsorption were studied. Langmuir, Freundlich and Temkin adsorption models were used to interpret the experimental data. The adsorption data were best fitted with Langmuir isotherm model. The adsorption capacity of Cr(VI) onto the activated carbon calculated from Langmuir isotherm was found to be 30.8 mg g−1 at pH 4.8 and temperature 303 K. The adsorption capacity increases from 25.36 to 32.04 mg g−1 with an increase in temperature from 303 to 323 K at initial Cr(VI) concentration of 60 mg L−1. The adsorption process followed a pseudo second order kinetic model. Thermodynamic parameters ΔH0 (28.6 KJ mol−1), ΔG0 at three different temperatures [(−0.145, −1.09, −2.04) KJ mol−1] and ΔS0 (94.87 J mol−1 K−1) were calculated. These values confirm the adsorption process to be endothermic and spontaneous in nature.

Electrochimica Acta, Jan 30, 2009

Coatings prepared from polyaniline–nano-TiO2 particles synthesized by in situ polymerization were... more Coatings prepared from polyaniline–nano-TiO2 particles synthesized by in situ polymerization were found to exhibit excellent corrosion resistance much superior to polyaniline (PANI) in aggressive environments. The corrosion studies were carried out on steel plates coated with these formulations containing 10wt% polyaniline prepared with different concentrations of nano-TiO2. The electrochemical impedance spectroscopy was studied at periodic intervals during exposure to hot saline (65° C) conditions for prolonged ...

Journal of Chemical & Engineering Data, 2015

Ab stract: Mark, trace and struc ture have been in con sis tently used in ichnology for many year... more Ab stract: Mark, trace and struc ture have been in con sis tently used in ichnology for many years; we wish to clar ify the or i gins and to pre scribe cor rect us age of these terms. The or i gins of the words are an cient and com plex; in the twen ti eth cen tury they were given clear def i ni tions as ichnologic terms. Seilacher (1953) de fined a mark (Ger man Marke) as a phys i cal (abiogenic) sed i men tary struc ture, as in the com mon terms sole mark, flute mark, but not bite mark or scratch mark. Trace has been de fined many times; we rec om mend the con sen sus def i ni tion of Bertling et al. (2006) as "a mor pho log i cally re cur rent struc ture re sult ing from the life ac tiv ity of an in di vid ual or gan ism (or homotypic or gan isms) mod i fy ing the sub strate"; this in cludes dwell ing trace, feed ing trace, bite trace. Struc ture, as im plied in an other con sen sus pa per (Frey, 1973), is a neu tral term for geo logic pat terns re sult ing from ei ther biogenic or abiogenic pro cesses. Use of the three terms in a clear con sis tent man ner will aid com mu ni ca tion both among ichnologists and be tween ichnologists and their col leagues in other fields.

Polymers are incredibly versatile materials in the modern-day world. Applications of polymers are... more Polymers are incredibly versatile materials in the modern-day world. Applications of polymers are highly diverse, which includes all fields of engineering from avionics to tissue engineering, biomedical applications, drug delivery system, cosmetics, biosensors, etc. Thus, processing and improvement of polymers such as development of biodegradable or biocompatible polymers via eco-friendly processes have gained much interest currently. Use of greener solvents in polymer synthesis and processing is a well acclaimed step toward making the polymer industry more popular and prosperous. In this chapter, various examples have been cited illustrating the use of water and supercritical water (SCW) as a polymerization medium. This chapter reviews the current status and future prospects of SCW in polymer technology. Many works have been reported till now highlighting the use of water or aqueous solutions as reaction media for polymer synthesis processes. Not much work has been reported on the ...

Journal of Energy Storage

New Journal of Chemistry

PANI-GO hybrid nanocomposites by the green interfacial polymerization method for electrochemical ... more PANI-GO hybrid nanocomposites by the green interfacial polymerization method for electrochemical capacitors and glucose sensors.

Ionics

The excellent cyclic efficiency, superior reversible charge/discharge rate, and high specific pow... more The excellent cyclic efficiency, superior reversible charge/discharge rate, and high specific power density have made supercapacitors an important class of energy storage systems in recent time. In this study, two nano-ceria-based composites were developed to use as electrode materials in supercapacitor applications. The composites were synthesized by combining ceria with conductive polyaniline (PANI) and doped with HCl and p-toluene sulfonic acid (PTSA). The materials were characterized by FTIR spectroscopy, SEM, XRD, and XPS techniques. Electrochemical studies were performed by cyclic voltammetry, galvanometric charge-discharge, and AC impedance spectroscopy. The CeO2-PANI doped with HCl and PTSA composites displayed ideal supercapacitor behavior showing higher capacitances up to 504 F g−1 and 454 F g−1, respectively, at current density of 1 A g−1 in comparison with pristine ceria (109 F g−1). Both the composites exhibited excellent specific energy (up to 100.8 W h kg−1) as well as outstanding specific power (up to 830 W kg−1). These findings support the possibility of these composites for practical applicability as electrode materials in energy storage devices.

In this study, we report an enormously simple green approach for the synthesis of polyaniline hyb... more In this study, we report an enormously simple green approach for the synthesis of polyaniline hybrid (PANI-SO) nanofibers in emeraldine salt form. We have carried out the synthesis via an interfacial polymerization method using vegetable oil as an organic phase instead of the commonly used solvents like CHCl 3 , CCl 4 , etc. Characterization techniques such as Fourier transform infrared (FTIR), UV−visible, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used for studying the synthesized polyaniline hybrid nanofibers. An interesting observation is the crystallization of small organic molecules in the PANI matrix. PANI-SO shows a pseudocapacitance behavior with a capacitance value of 302 F g −1 at a current density of 1 A g −1. In addition, the material shows an energy density of 26.8 W h kg −1 and a maximum power density of 402.6 W kg −1. Furthermore, the PANI-SO electrode maintains about 84% of the initial capacitance after 1000 cycles. Similarly, the PANI-SO symmetric solid-state supercapacitor shows an areal capacitance of 118.7 mF cm −2 and retains a stability of 80% even after 1000 cycles. Thus, the PANI-SO electrode shows a good cyclic performance, which implies the structural stability of PANI-SO nanofibers. The electrochemical properties of PANI-SO are compared with those of PANI nanofibers synthesized by taking CHCl 3 as the organic phase and keeping all other parameters identical. PANI-SO is observed to be a superior material compared to the latter one. All electrochemical analyses show that the PANI synthesized using cooking soyabean oil (PANI-SO) is an effective supercapacitor material.

Journal of Solid State Chemistry, Oct 1, 2007

Heterogeneous conducting polymer composites (organic/inorganic) have been attracting attention ow... more Heterogeneous conducting polymer composites (organic/inorganic) have been attracting attention owing to their applications in various fields [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15] and [16] such as charge storage materials, catalysts, solar cells [8], [9] and ...

Physical Chemistry Chemical Physics

The K+ ion electrochemistry of graphite in aqueous batteries is illustrated.

Materials Today Communications

Journal of Energy Storage

Journal of Energy Storage

ACS Omega, 2021

This study proposes the development of an electrochemical sensor based on fabrication of a glassy... more This study proposes the development of an electrochemical sensor based on fabrication of a glassy carbon electrode (GCE) with Fe 3 O 4-polyaniline (Fe 3 O 4-PANI) nanocomposite, which was further used for enzyme-less detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous medium. Spectroscopic studies, microstructural studies, and elemental analysis established the formation of Fe 3 O 4 nanoparticles with polyaniline coating. The fabricated Fe 3 O 4-PANI-GCE was characterized by electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical response of 2,4-D on Fe 3 O 4-PANI-GCE was evaluated by performing cyclic voltammetry and amperometry experiments. The synergistic effect of the composite causes the superior electrochemical behavior of Fe 3 O 4-PANI-GCE toward the detection of 2,4-D. Amperometric measurements exhibited a linear concentration range from 1.35 to 2.7 μM. The sensitivity and detection limit were evaluated from the amperometric responses, which were found to be 4.62 × 10 −7 μA μM −1 cm −2 and 0.21 μM, respectively. The electrochemical sensing response could be attributed to adsorption of 2,4-D onto the Fe 3 O 4-PANImodified GCE (Fe 3 O 4-PANI-GCE) surface. Fe 3 O 4-PANI-GCE is found to be a simple, low-cost, and biocompatible non-enzymatic sensor for detection of 2,4-D in aqueous medium at ambient temperature.

Journal of Porous Materials, 2014

A new porous carbon with high surface area of 1,313.41 m2 g−1 with pore volume 1.359 cm3 g−1 has ... more A new porous carbon with high surface area of 1,313.41 m2 g−1 with pore volume 1.359 cm3 g−1 has been synthesized from matured tea leaves by chemical activation method using phosphoric acid. The carbon was found to be highly efficient for removal of Cr(VI) from aqueous solution. The effects of various parameters such as contact time, initial metal ion concentration, pH, temperature and amount of adsorbent on the extent of adsorption were studied. Langmuir, Freundlich and Temkin adsorption models were used to interpret the experimental data. The adsorption data were best fitted with Langmuir isotherm model. The adsorption capacity of Cr(VI) onto the activated carbon calculated from Langmuir isotherm was found to be 30.8 mg g−1 at pH 4.8 and temperature 303 K. The adsorption capacity increases from 25.36 to 32.04 mg g−1 with an increase in temperature from 303 to 323 K at initial Cr(VI) concentration of 60 mg L−1. The adsorption process followed a pseudo second order kinetic model. Thermodynamic parameters ΔH0 (28.6 KJ mol−1), ΔG0 at three different temperatures [(−0.145, −1.09, −2.04) KJ mol−1] and ΔS0 (94.87 J mol−1 K−1) were calculated. These values confirm the adsorption process to be endothermic and spontaneous in nature.

Electrochimica Acta, Jan 30, 2009

Coatings prepared from polyaniline–nano-TiO2 particles synthesized by in situ polymerization were... more Coatings prepared from polyaniline–nano-TiO2 particles synthesized by in situ polymerization were found to exhibit excellent corrosion resistance much superior to polyaniline (PANI) in aggressive environments. The corrosion studies were carried out on steel plates coated with these formulations containing 10wt% polyaniline prepared with different concentrations of nano-TiO2. The electrochemical impedance spectroscopy was studied at periodic intervals during exposure to hot saline (65° C) conditions for prolonged ...

Journal of Chemical & Engineering Data, 2015

Ab stract: Mark, trace and struc ture have been in con sis tently used in ichnology for many year... more Ab stract: Mark, trace and struc ture have been in con sis tently used in ichnology for many years; we wish to clar ify the or i gins and to pre scribe cor rect us age of these terms. The or i gins of the words are an cient and com plex; in the twen ti eth cen tury they were given clear def i ni tions as ichnologic terms. Seilacher (1953) de fined a mark (Ger man Marke) as a phys i cal (abiogenic) sed i men tary struc ture, as in the com mon terms sole mark, flute mark, but not bite mark or scratch mark. Trace has been de fined many times; we rec om mend the con sen sus def i ni tion of Bertling et al. (2006) as "a mor pho log i cally re cur rent struc ture re sult ing from the life ac tiv ity of an in di vid ual or gan ism (or homotypic or gan isms) mod i fy ing the sub strate"; this in cludes dwell ing trace, feed ing trace, bite trace. Struc ture, as im plied in an other con sen sus pa per (Frey, 1973), is a neu tral term for geo logic pat terns re sult ing from ei ther biogenic or abiogenic pro cesses. Use of the three terms in a clear con sis tent man ner will aid com mu ni ca tion both among ichnologists and be tween ichnologists and their col leagues in other fields.

Polymers are incredibly versatile materials in the modern-day world. Applications of polymers are... more Polymers are incredibly versatile materials in the modern-day world. Applications of polymers are highly diverse, which includes all fields of engineering from avionics to tissue engineering, biomedical applications, drug delivery system, cosmetics, biosensors, etc. Thus, processing and improvement of polymers such as development of biodegradable or biocompatible polymers via eco-friendly processes have gained much interest currently. Use of greener solvents in polymer synthesis and processing is a well acclaimed step toward making the polymer industry more popular and prosperous. In this chapter, various examples have been cited illustrating the use of water and supercritical water (SCW) as a polymerization medium. This chapter reviews the current status and future prospects of SCW in polymer technology. Many works have been reported till now highlighting the use of water or aqueous solutions as reaction media for polymer synthesis processes. Not much work has been reported on the ...

Journal of Energy Storage

New Journal of Chemistry

PANI-GO hybrid nanocomposites by the green interfacial polymerization method for electrochemical ... more PANI-GO hybrid nanocomposites by the green interfacial polymerization method for electrochemical capacitors and glucose sensors.

Ionics

The excellent cyclic efficiency, superior reversible charge/discharge rate, and high specific pow... more The excellent cyclic efficiency, superior reversible charge/discharge rate, and high specific power density have made supercapacitors an important class of energy storage systems in recent time. In this study, two nano-ceria-based composites were developed to use as electrode materials in supercapacitor applications. The composites were synthesized by combining ceria with conductive polyaniline (PANI) and doped with HCl and p-toluene sulfonic acid (PTSA). The materials were characterized by FTIR spectroscopy, SEM, XRD, and XPS techniques. Electrochemical studies were performed by cyclic voltammetry, galvanometric charge-discharge, and AC impedance spectroscopy. The CeO2-PANI doped with HCl and PTSA composites displayed ideal supercapacitor behavior showing higher capacitances up to 504 F g−1 and 454 F g−1, respectively, at current density of 1 A g−1 in comparison with pristine ceria (109 F g−1). Both the composites exhibited excellent specific energy (up to 100.8 W h kg−1) as well as outstanding specific power (up to 830 W kg−1). These findings support the possibility of these composites for practical applicability as electrode materials in energy storage devices.

In this study, we report an enormously simple green approach for the synthesis of polyaniline hyb... more In this study, we report an enormously simple green approach for the synthesis of polyaniline hybrid (PANI-SO) nanofibers in emeraldine salt form. We have carried out the synthesis via an interfacial polymerization method using vegetable oil as an organic phase instead of the commonly used solvents like CHCl 3 , CCl 4 , etc. Characterization techniques such as Fourier transform infrared (FTIR), UV−visible, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used for studying the synthesized polyaniline hybrid nanofibers. An interesting observation is the crystallization of small organic molecules in the PANI matrix. PANI-SO shows a pseudocapacitance behavior with a capacitance value of 302 F g −1 at a current density of 1 A g −1. In addition, the material shows an energy density of 26.8 W h kg −1 and a maximum power density of 402.6 W kg −1. Furthermore, the PANI-SO electrode maintains about 84% of the initial capacitance after 1000 cycles. Similarly, the PANI-SO symmetric solid-state supercapacitor shows an areal capacitance of 118.7 mF cm −2 and retains a stability of 80% even after 1000 cycles. Thus, the PANI-SO electrode shows a good cyclic performance, which implies the structural stability of PANI-SO nanofibers. The electrochemical properties of PANI-SO are compared with those of PANI nanofibers synthesized by taking CHCl 3 as the organic phase and keeping all other parameters identical. PANI-SO is observed to be a superior material compared to the latter one. All electrochemical analyses show that the PANI synthesized using cooking soyabean oil (PANI-SO) is an effective supercapacitor material.