We report the synthesis and structural characterization of a bimetallic zinc selenolate complex c... more We report the synthesis and structural characterization of a bimetallic zinc selenolate complex consisting of a redox silent zinc metal ion and a trifunctional ligand that electrocatalyzes the reduction of protons into hydrogen gas.
Role of temperature has been investigated for multifarious nanoporous carbon having physisorbed h... more Role of temperature has been investigated for multifarious nanoporous carbon having physisorbed hydroquinone.
We have explored Co3O4 based nanomaterials for the oxygen evolution reaction prepared via a surfa... more We have explored Co3O4 based nanomaterials for the oxygen evolution reaction prepared via a surfactant directed soft-templating strategy.
Correction for ‘Selective synthesis of single layer translucent cobalt hydroxide for the efficien... more Correction for ‘Selective synthesis of single layer translucent cobalt hydroxide for the efficient oxygen evolution reaction’ by Priyajit Jash et al., Chem. Commun., 2019, 55, 2230–2233.
Remarkable water oxidation reactivity exhibited by a translucent single layer Co(OH)2 nanosheet s... more Remarkable water oxidation reactivity exhibited by a translucent single layer Co(OH)2 nanosheet synthesized from α-Co(OH)2 by liquid phase exfoliation.
The work reported here aims toward the optimization of electrode preparation methodologies for su... more The work reported here aims toward the optimization of electrode preparation methodologies for superior performance of supercapacitors through a rigorous understanding of underlying physical parameters. Oxygenfunctionalized few-layer graphene was employed as an active material while binders [Nafion, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene], solvents for active material dispersion [ethylene glycol and N-methyl-2-pyrrolidone (NMP)], and electrode-drying temperatures (100, 170, and 190°C) were varied. Maximum specific capacitances at different electrode preparation conditions ranged from 240 to 318 F g −1 at 1 mV s −1 scan rate of cyclic voltammetry for the same active material. The study revealed that the electrodes prepared using the PVDF binder, the NMP solvent for active material dispersion, 170°C electrode-drying temperature (slightly below the boiling temperature of the solvent) provided the best electrochemical performance. Electrochemical impedance spectroscopy revealed that the resistance for electron transfer at the electrode/electrolyte interface can be minimized while mass transport and pseudocapacitive charging can be improved significantly by tuning electrode preparation methodologies which resulted in smaller time constants and hence better capacitor performances. Scanning electron microscopy images revealed that graphene layers were properly stacked much similar to the synthesized nanomaterial wherein better electrochemical performances were achieved, avoiding the agglomeration of nanomaterials on the electrode surface. Low viscosity of the solvent for active material dispersion and better solubility of the binder in the solvent helped to reduce the agglomeration of nanomaterials by minimizing the strong van der Waals interaction which causes agglomeration.
Chemical communications (Cambridge, England), Jan 16, 2018
A novel class of pyrene-based conjugated porous organic polymers having an N-containing network w... more A novel class of pyrene-based conjugated porous organic polymers having an N-containing network was developed by employing Buchwald-Hartwig coupling for supercapacitor energy storage. The pristine polymer was found to exhibit a specific capacitance of 456 F g-1 at 0.5 A g-1 current density with excellent long-term cyclic stability.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 30, 2017
We report a simple approach for the synthesis of cobalt phosphonate (CoOP) nanocages with two dis... more We report a simple approach for the synthesis of cobalt phosphonate (CoOP) nanocages with two distinct types of pore diameters by utilizing a novel tetra-constituent assembly of CoCl2 ⋅6 H2 O, nitrilotris(methylene)triphosphonic acid (NMPA), F127 surfactant, and polyvinyl alcohol (PVA, co-surfactant). Transmission electron microscopy images revealed the formation of large nanocages in spheres (pore diameter: 20-60 nm) and the existence of narrow micro/mesopores (pore diameter: 1.5-5 nm) on their walls. Brunauer-Emmett-Teller adsorption/desorption experiments led to the observation of dual porosity and indicated that the contribution of micro/mesopores increased gradually with increasing concentration of PVA during synthesis from CoOP-0 to CoOP-15 (where the number gives the wt % of PVA used in CoOP synthesis). These materials acted as precatalysts for heterogeneous water oxidation at pH 13.9 (1 m KOH) and electrochemical studies revealed that the reactivity improved remarkably with ...
Two-dimensional redox-active covalent organic frameworks (COFs) are ideal materials for energy st... more Two-dimensional redox-active covalent organic frameworks (COFs) are ideal materials for energy storage applications due to their high surface area, extended π conjugated structure, tunable pore size and adjustable functionalities.[1-3] Herein, we report the synthesis and supercapacitor application of two redox active COFs [TpPa-(OH)2 and TpBD-(OH)2] along with the role of their redox active functional groups for the enrichment of specific capacitance.3 Of these COFs, TpPa-(OH)2 exhibited the highest specific capacitance of 416 F g−1 at 0.5 A g−1 current density in three electrode configuration while the highest specific capacitance was 214 F g−1 at 0.2 A g−1 current density in two electrode configuration. Superior specific capacitance was due to emergence of excellent pseudocapacitance by virtue of precise molecular level control over redox functionalities present in the COF backbone. This COF also demonstrated 66% capacitance retention after 10000 cycles along with 43% accessibility of the redox-active hydroquinone (H2Q) moieties in three electrode configuration while the capacitance retention was 88% after 10000 cycles in two electrode configuration. Exceptionally high specific capacitance of TpPa-(OH)2 was due to the reversible proton-coupled electron transfer (2H+/2e−) of hydroquinone/benzoquinone (H2Q/Q) moieties wherein H2Q and Q had comparable chemical stabilities during redox cycling that originated from H-bonding, which was supported by calculated structures.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 19, 2017
Manganese dioxide nanomaterials with "Koosh-ball" like morphology (MnO2-KBs) as well as... more Manganese dioxide nanomaterials with "Koosh-ball" like morphology (MnO2-KBs) as well as worm-like nanotubes (MnO2-NWs) were obtained by employing Tween 20 as the reducing-cum-structure-directing agent, and KMnO4 as a MnO2 precursor. While the MnO2-KBs were interconnected with each other through tubular extensions, MnO2-NWs were largely disconnected. Both MnO2-KBs and MnO2-NWs had large BET surface areas (>200 m2/g), and were thermally robust upto 300 ⁰C. The electrochemical studies revealed that the highest specific capacitance (Csp) obtained for MnO2-KBs was significantly higher (272 F/g) than that of MnO2-NWs (129 F/g). The Csp values correlated amicably with the electroactive surface areas of the material - MnO2-KBs had significantly higher electrolyte-accessible surface area. Electrochemical impedance spectroscopy (EIS) revealed higher electron transfer rate at the electrode/electrolyte interface for MnO2-KBs than that of MnO2-NWs. The multiple tubular interconnecti...
The authors regret that the values denoted on the y-axis of Fig. 3(d) are incorrect in the origin... more The authors regret that the values denoted on the y-axis of Fig. 3(d) are incorrect in the original article. A revised version of Fig. 3, in which the y-axis of Fig. 3(d) has been corrected, is included herein. In addition to the above, the authors would also like to include the following text at the end of the paragraph beginning ''Maier and Tuller highlighted the importance of.. .'' on page 12664: ''Besides, proton conduction in the bulk synthesized GO(150) is restricted due to turbostratic stacking of the layers, i.e. interruptions originating from interlayer interactions 9 and such interruptions are not applicable for OFG(150). Finally, the higher sp 2 carbon content of OFG(150) presumably enhances in-plane conduction compared to through-plane conduction, which also helps to achieve higher conductivity.'' The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. Fig. 3 Nyquist plots of (a) OFG(150) and (b) GO(150) with s values at a particular RH (%) and temperature. (c) s vs. RH (%) at 27 1C for OFG(150) and GO(150). (d) Plots of ln(sT) vs. T À1 for OFG(150) and GO(150) at 95% RH.
The first demonstration of solid state proton conduction (8.7 × 10−3 S cm−1 at 80 °C, 95% relativ... more The first demonstration of solid state proton conduction (8.7 × 10−3 S cm−1 at 80 °C, 95% relative humidity) of oxygen functionalized few-layer graphene.
Iron oxyhydroxide thin films electrochemically deposited from a non-aqueous medium using metal in... more Iron oxyhydroxide thin films electrochemically deposited from a non-aqueous medium using metal inorganic complexes as a metal ion precursor have been demonstrated as an efficient electrochemical water oxidation catalyst under near neutral as well as alkaline pH conditions.
An economical and simple low temperature chemically assisted reduced graphene synthesis has been ... more An economical and simple low temperature chemically assisted reduced graphene synthesis has been reported and the obtained graphene exhibits very high electrical conductivity (1.6 × 103 S cm−1).
A proof of concept to enhance the specific capacitance and energy density of a supercapacitor has... more A proof of concept to enhance the specific capacitance and energy density of a supercapacitor has been demonstrated wherein reversible 1e- transfer redox chemistry of cations of ionic liquids ([EMIM][EtSO4] and [MIM][HSO4]) which acted as both solvent and electrolyte has been utilized. Outstanding specific capacitance and energy densities in the range of 420-710 F/g and 580-920 Wh/kg, respectively, have been obtained for carbon-based nanomaterials.
The first report of oxygen functionalized few-layer graphene (OFG)
having an interlayer distance ... more The first report of oxygen functionalized few-layer graphene (OFG) having an interlayer distance of 3.6 Å as an excellent proton conductor (8.7 103 S cm1 at 80 8C, 95% RH) utilizing hydrophilic oxygen functionalities present at sheet edges bypassing the theoretical limitation of proton conduction through a basal plane. The synthesized OFG also exhibited excellent supercapacitor performance (296 F g1).
The effect of molecular chirality on electron transmission is explored by photoelectrochemistry. ... more The effect of molecular chirality on electron transmission is explored by photoelectrochemistry. Thiol-terminated chiral scaffold molecules containing a porphyrin chromophore were self-assembled on gold surfaces to form a monolayer. Incorporation of the SAM-coated gold into an electrochemical cell and illumination with visible light generated a cathodic photocurrent. When using circularly polarized light, the photocurrent displayed an asymmetry (different magnitude of photocurrent for right versus left polarization) that changed with the molecular chirality (left- or right-handedness of the scaffold). A symmetry constraint on the electronic coupling between the porphyrin and the organic scaffold is proposed as a possible mechanism for the photocurrent asymmetry.
We report the synthesis and structural characterization of a bimetallic zinc selenolate complex c... more We report the synthesis and structural characterization of a bimetallic zinc selenolate complex consisting of a redox silent zinc metal ion and a trifunctional ligand that electrocatalyzes the reduction of protons into hydrogen gas.
Role of temperature has been investigated for multifarious nanoporous carbon having physisorbed h... more Role of temperature has been investigated for multifarious nanoporous carbon having physisorbed hydroquinone.
We have explored Co3O4 based nanomaterials for the oxygen evolution reaction prepared via a surfa... more We have explored Co3O4 based nanomaterials for the oxygen evolution reaction prepared via a surfactant directed soft-templating strategy.
Correction for ‘Selective synthesis of single layer translucent cobalt hydroxide for the efficien... more Correction for ‘Selective synthesis of single layer translucent cobalt hydroxide for the efficient oxygen evolution reaction’ by Priyajit Jash et al., Chem. Commun., 2019, 55, 2230–2233.
Remarkable water oxidation reactivity exhibited by a translucent single layer Co(OH)2 nanosheet s... more Remarkable water oxidation reactivity exhibited by a translucent single layer Co(OH)2 nanosheet synthesized from α-Co(OH)2 by liquid phase exfoliation.
The work reported here aims toward the optimization of electrode preparation methodologies for su... more The work reported here aims toward the optimization of electrode preparation methodologies for superior performance of supercapacitors through a rigorous understanding of underlying physical parameters. Oxygenfunctionalized few-layer graphene was employed as an active material while binders [Nafion, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene], solvents for active material dispersion [ethylene glycol and N-methyl-2-pyrrolidone (NMP)], and electrode-drying temperatures (100, 170, and 190°C) were varied. Maximum specific capacitances at different electrode preparation conditions ranged from 240 to 318 F g −1 at 1 mV s −1 scan rate of cyclic voltammetry for the same active material. The study revealed that the electrodes prepared using the PVDF binder, the NMP solvent for active material dispersion, 170°C electrode-drying temperature (slightly below the boiling temperature of the solvent) provided the best electrochemical performance. Electrochemical impedance spectroscopy revealed that the resistance for electron transfer at the electrode/electrolyte interface can be minimized while mass transport and pseudocapacitive charging can be improved significantly by tuning electrode preparation methodologies which resulted in smaller time constants and hence better capacitor performances. Scanning electron microscopy images revealed that graphene layers were properly stacked much similar to the synthesized nanomaterial wherein better electrochemical performances were achieved, avoiding the agglomeration of nanomaterials on the electrode surface. Low viscosity of the solvent for active material dispersion and better solubility of the binder in the solvent helped to reduce the agglomeration of nanomaterials by minimizing the strong van der Waals interaction which causes agglomeration.
Chemical communications (Cambridge, England), Jan 16, 2018
A novel class of pyrene-based conjugated porous organic polymers having an N-containing network w... more A novel class of pyrene-based conjugated porous organic polymers having an N-containing network was developed by employing Buchwald-Hartwig coupling for supercapacitor energy storage. The pristine polymer was found to exhibit a specific capacitance of 456 F g-1 at 0.5 A g-1 current density with excellent long-term cyclic stability.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 30, 2017
We report a simple approach for the synthesis of cobalt phosphonate (CoOP) nanocages with two dis... more We report a simple approach for the synthesis of cobalt phosphonate (CoOP) nanocages with two distinct types of pore diameters by utilizing a novel tetra-constituent assembly of CoCl2 ⋅6 H2 O, nitrilotris(methylene)triphosphonic acid (NMPA), F127 surfactant, and polyvinyl alcohol (PVA, co-surfactant). Transmission electron microscopy images revealed the formation of large nanocages in spheres (pore diameter: 20-60 nm) and the existence of narrow micro/mesopores (pore diameter: 1.5-5 nm) on their walls. Brunauer-Emmett-Teller adsorption/desorption experiments led to the observation of dual porosity and indicated that the contribution of micro/mesopores increased gradually with increasing concentration of PVA during synthesis from CoOP-0 to CoOP-15 (where the number gives the wt % of PVA used in CoOP synthesis). These materials acted as precatalysts for heterogeneous water oxidation at pH 13.9 (1 m KOH) and electrochemical studies revealed that the reactivity improved remarkably with ...
Two-dimensional redox-active covalent organic frameworks (COFs) are ideal materials for energy st... more Two-dimensional redox-active covalent organic frameworks (COFs) are ideal materials for energy storage applications due to their high surface area, extended π conjugated structure, tunable pore size and adjustable functionalities.[1-3] Herein, we report the synthesis and supercapacitor application of two redox active COFs [TpPa-(OH)2 and TpBD-(OH)2] along with the role of their redox active functional groups for the enrichment of specific capacitance.3 Of these COFs, TpPa-(OH)2 exhibited the highest specific capacitance of 416 F g−1 at 0.5 A g−1 current density in three electrode configuration while the highest specific capacitance was 214 F g−1 at 0.2 A g−1 current density in two electrode configuration. Superior specific capacitance was due to emergence of excellent pseudocapacitance by virtue of precise molecular level control over redox functionalities present in the COF backbone. This COF also demonstrated 66% capacitance retention after 10000 cycles along with 43% accessibility of the redox-active hydroquinone (H2Q) moieties in three electrode configuration while the capacitance retention was 88% after 10000 cycles in two electrode configuration. Exceptionally high specific capacitance of TpPa-(OH)2 was due to the reversible proton-coupled electron transfer (2H+/2e−) of hydroquinone/benzoquinone (H2Q/Q) moieties wherein H2Q and Q had comparable chemical stabilities during redox cycling that originated from H-bonding, which was supported by calculated structures.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 19, 2017
Manganese dioxide nanomaterials with "Koosh-ball" like morphology (MnO2-KBs) as well as... more Manganese dioxide nanomaterials with "Koosh-ball" like morphology (MnO2-KBs) as well as worm-like nanotubes (MnO2-NWs) were obtained by employing Tween 20 as the reducing-cum-structure-directing agent, and KMnO4 as a MnO2 precursor. While the MnO2-KBs were interconnected with each other through tubular extensions, MnO2-NWs were largely disconnected. Both MnO2-KBs and MnO2-NWs had large BET surface areas (>200 m2/g), and were thermally robust upto 300 ⁰C. The electrochemical studies revealed that the highest specific capacitance (Csp) obtained for MnO2-KBs was significantly higher (272 F/g) than that of MnO2-NWs (129 F/g). The Csp values correlated amicably with the electroactive surface areas of the material - MnO2-KBs had significantly higher electrolyte-accessible surface area. Electrochemical impedance spectroscopy (EIS) revealed higher electron transfer rate at the electrode/electrolyte interface for MnO2-KBs than that of MnO2-NWs. The multiple tubular interconnecti...
The authors regret that the values denoted on the y-axis of Fig. 3(d) are incorrect in the origin... more The authors regret that the values denoted on the y-axis of Fig. 3(d) are incorrect in the original article. A revised version of Fig. 3, in which the y-axis of Fig. 3(d) has been corrected, is included herein. In addition to the above, the authors would also like to include the following text at the end of the paragraph beginning ''Maier and Tuller highlighted the importance of.. .'' on page 12664: ''Besides, proton conduction in the bulk synthesized GO(150) is restricted due to turbostratic stacking of the layers, i.e. interruptions originating from interlayer interactions 9 and such interruptions are not applicable for OFG(150). Finally, the higher sp 2 carbon content of OFG(150) presumably enhances in-plane conduction compared to through-plane conduction, which also helps to achieve higher conductivity.'' The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. Fig. 3 Nyquist plots of (a) OFG(150) and (b) GO(150) with s values at a particular RH (%) and temperature. (c) s vs. RH (%) at 27 1C for OFG(150) and GO(150). (d) Plots of ln(sT) vs. T À1 for OFG(150) and GO(150) at 95% RH.
The first demonstration of solid state proton conduction (8.7 × 10−3 S cm−1 at 80 °C, 95% relativ... more The first demonstration of solid state proton conduction (8.7 × 10−3 S cm−1 at 80 °C, 95% relative humidity) of oxygen functionalized few-layer graphene.
Iron oxyhydroxide thin films electrochemically deposited from a non-aqueous medium using metal in... more Iron oxyhydroxide thin films electrochemically deposited from a non-aqueous medium using metal inorganic complexes as a metal ion precursor have been demonstrated as an efficient electrochemical water oxidation catalyst under near neutral as well as alkaline pH conditions.
An economical and simple low temperature chemically assisted reduced graphene synthesis has been ... more An economical and simple low temperature chemically assisted reduced graphene synthesis has been reported and the obtained graphene exhibits very high electrical conductivity (1.6 × 103 S cm−1).
A proof of concept to enhance the specific capacitance and energy density of a supercapacitor has... more A proof of concept to enhance the specific capacitance and energy density of a supercapacitor has been demonstrated wherein reversible 1e- transfer redox chemistry of cations of ionic liquids ([EMIM][EtSO4] and [MIM][HSO4]) which acted as both solvent and electrolyte has been utilized. Outstanding specific capacitance and energy densities in the range of 420-710 F/g and 580-920 Wh/kg, respectively, have been obtained for carbon-based nanomaterials.
The first report of oxygen functionalized few-layer graphene (OFG)
having an interlayer distance ... more The first report of oxygen functionalized few-layer graphene (OFG) having an interlayer distance of 3.6 Å as an excellent proton conductor (8.7 103 S cm1 at 80 8C, 95% RH) utilizing hydrophilic oxygen functionalities present at sheet edges bypassing the theoretical limitation of proton conduction through a basal plane. The synthesized OFG also exhibited excellent supercapacitor performance (296 F g1).
The effect of molecular chirality on electron transmission is explored by photoelectrochemistry. ... more The effect of molecular chirality on electron transmission is explored by photoelectrochemistry. Thiol-terminated chiral scaffold molecules containing a porphyrin chromophore were self-assembled on gold surfaces to form a monolayer. Incorporation of the SAM-coated gold into an electrochemical cell and illumination with visible light generated a cathodic photocurrent. When using circularly polarized light, the photocurrent displayed an asymmetry (different magnitude of photocurrent for right versus left polarization) that changed with the molecular chirality (left- or right-handedness of the scaffold). A symmetry constraint on the electronic coupling between the porphyrin and the organic scaffold is proposed as a possible mechanism for the photocurrent asymmetry.
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Papers by Amit Paul
having an interlayer distance of 3.6 Å as an excellent proton conductor
(8.7 103 S cm1 at 80 8C, 95% RH) utilizing hydrophilic oxygen
functionalities present at sheet edges bypassing the theoretical limitation
of proton conduction through a basal plane. The synthesized OFG
also exhibited excellent supercapacitor performance (296 F g1).
having an interlayer distance of 3.6 Å as an excellent proton conductor
(8.7 103 S cm1 at 80 8C, 95% RH) utilizing hydrophilic oxygen
functionalities present at sheet edges bypassing the theoretical limitation
of proton conduction through a basal plane. The synthesized OFG
also exhibited excellent supercapacitor performance (296 F g1).