@article { ISI:000325548600016, title = {Redox-mediated synthesis of functionalised graphene: a strategy towards 2D multifunctional electrocatalysts for energy conversion applications}, journal = {ChemPlusChem}, volume = {78}, number = {10}, year = {2013}, month = {OCT}, pages = {1296-1303}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A simple, one-step synthetic route for developing a two-dimensional multifunctional electrocatalyst is reported, by the functionalisation of graphene using oxidised ethylenedioxythiophene (O-EDOT). The mutually assisted redox reaction between graphene oxide (GO) and EDOT facilitates the reduction of GO to graphene with a concomitant deposition of O-EDOT on the surface of the graphene. The oxidised surface of GO catalyses the reaction without using an added reducing agent, so a controlled and uniform deposition of O-EDOT is ensured on the surface of graphene, which essentially prevents the restacking of the layers. UV/Visible, IR, Raman and X-ray photoelectron spectroscopy give valid evidence for the reduction and functionalisation of graphene sheets. The functional groups present on the surface of graphene are found to tune the physical and chemical properties of graphene. Consequently, the functionalised material displays enhanced electrocatalytic activity for the reduction of oxygen to water and I3- to I- relative to pristine graphene. These distinct property characteristics make the material a versatile cathode electrocatalyst for both alkaline anion-exchange membrane fuel cells and dye-sensitised solar cells.

}, keywords = {electrocatalysts, fuel cells, graphene, redox chemistry, solar cells}, issn = {2192-6506}, doi = {10.1002/cplu.201300153}, author = {Unni, SreeKuttan M. and Bhange, Siddheshwar N. and Anothumakkool, Bihag and Kurungot, Sreekumar} } @article {45632, title = {Reduced graphene oxide modified electrodes for sensitive sensing of gliadin in food samples}, journal = {ACS Sensors}, volume = {1}, year = {2016}, month = {DEC}, pages = {1462-1470}, type = {Article}, abstract = {

Incidences of food allergies are on the rise, which can greatly affect the well-being of children as well as adults. Intolerance to gluten, a protein composite of gliadin and glutenin, present in wheat, barley, and rye and several cereals, can be the causative agent of celiac disease (CD) and other allergic reactions. A gluten-free diet has become essential for people affected by CD, and consequently, the amount of gluten in food products needs to be strictly controlled. In this paper, we report an electrochemical label-free immunosensor for ultrasensitive and specific detection of gliadin. The sensor takes advantage of the specific properties of porous reduced graphene oxide (prGO) covalently functionalized with anti-gliadin antibodies using 1-pyrenecarboxylic acid as linker molecule. Using differential pulse voltammetry (DPV) and [Fe(CN)6](3-/4-) as a redox probe, a decrease of current is linked to the presence of gliadin. The sensor achieved a detection limit of 1.2 ng mL(-1) over a 1.2-34 ng mL(-1) linear range with high selectivity. The advantages offered by this sensor are the possibility to regenerate the surface of the immunosensor, its rapid and ease of production, as well as applicability for the screening of gliadin concentrations in real food samples, as shown here.

}, keywords = {anti-gliadin antibody, food samples, gliadin, Immunosensor, Porous reduced graphene oxide}, issn = {2379-3694}, doi = {10.1021/acssensors.6b00608}, author = {Chekin, Fereshteh and Singh, Santosh K. and Vasilescu, Alina and Dhavale, Vishal M. and Kurungot, Sreekumar and Boukherroub, Rabah and Szunerits, Sabine} } @article {44373, title = {Rationally designed self-standing V2O5 electrode for high voltage non-aqueous all-solid-state symmetric (2.0 V) and asymmetric (2.8 V) supercapacitors}, journal = {Nanoscale}, volume = {10}, year = {2018}, month = {MAY}, pages = {8741-8751}, abstract = {The maximum capacitive potential window of certain pseudocapacitive materials cannot be accessed in aqueous electrolytes owing to the low dissociation potential of 1.2 V possessed by water molecules. However, the inferior pseudocapacitance exhibited by the commonly used electrode materials when integrated with non-aqueous electrolytes still remains a challenge in the development of supercapacitors (SC). Proper selection of materials for the electrode and a rational design process are indeed important to overcome these practical intricacies so that such systems can perform well with non-aqueous electrolytes. We address this challenge by fabricating a prototype all-solid-state device designed with high-capacitive V2O5 as the electrode material along with a Li-ion conducting organic electrolyte. V2O5 is synthesized on a pre-treated carbon-fibre paper by adopting an electrochemical deposition technique that effects an improved contact resistance. A judicious electrode preparation strategy makes it possible to overcome the constraints of the low ionic and electrical conductivities imposed by the electrolyte and electrode material, respectively. The device, assembled in a symmetrical fashion, achieves a high specific capacitance of 406 F g(-1) (at 1 A g(-1)). The profitable aspect of using an organic electrolyte is also demonstrated with an asymmetric configuration by using activated carbon as the positive and V2O5 as the negative electrode materials, respectively. The asymmetric device displays a wide working-voltage window of 2.8 V and delivers a high energy density of 102.68 W h kg(-1) at a power density of 1.49 kW kg(-1). Moreover, the low equivalent series resistance of 9.9 Omega and negligible charge transfer resistance are observed in the impedance spectra, which is a key factor that accounts for such an exemplary performance.}, doi = {10.1039/c8nr00805a}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Soni, Roby and Kurungot, Sreekumar} } @article {44218, title = {Realizing high capacitance and rate capability in polyaniline by enhancing the electrochemical surface area through induction of superhydrophilicity}, journal = {ACS Applied Materials \& Interfaces}, volume = {10}, year = {2018}, month = {JAN}, pages = {676-686}, type = {Article}, abstract = {

Polyaniline (PANI) as a pseudocapacitive material has very high theoretical capacitance of 2000 F g(-1). However, its practical capacitance has been limited by low electrochemical surface area (ESA) and unfavorable wettability toward aqueous electrolytes. This work deals with a strategy wherein the high ESA of PANI has been achieved by the induction of superhydrophilicity together with the alignment of PANI exclusively on the surface of carbon fibers as a thin layer to form a hybrid assembly. Superhydrophilicity is induced by electrochemical functionalization of the Toray carbon paper, which further induces superhydrophilicity to the electrodeposited PANI layer on the paper, thereby ensuring a high electrode-electrolyte interface. The Toray paper is electrochemically functionalized by the anodization method, which generates a highly active electrochemical surface as well as greater wettability (superhydrophilic) of the carbon fibers. Because of the strong interaction of anilinium chloride with the hydrophilic carbon surface, PANI is polymerized exclusively over the surface of the fibers without any appreciable aggregation or agglomeration of the polymer. The PANI-Toray paper assembly in the solid-state prototype supercapacitor can provide a high gravimetric capacitance of 1335 F g(-1) as well as a high areal capacitance of 1.3 F cm(-2) at a current density of 10 A g(-1). The device also exhibits high rate capability, delivering 1217 F g(-1) at a current density of 50 A g(-1) and a high energy density of 30 W h kg(-1) at a power density of 2 kW kg(-1).

}, keywords = {electrochemical active sulfate area, electrochemical functionalization, electropolymerization, polyaniline, supercapacitor, superhydrophilic}, issn = {1944-8244}, doi = {10.1021/acsami.7b15534}, author = {Soni, Roby and Kashyap, Varchaswal and Nagaraju, Divya and Kurungot, Sreekumar} } @article {44643, title = {Repeated photoporation with graphene quantum dots enables homogeneous labeling of live cells with extrinsic markers for fluorescence microscopy}, journal = {Light-Science \& Applications}, volume = {7}, year = {2018}, month = {AUG}, pages = {47}, abstract = {

In the replacement of genetic probes, there is increasing interest in labeling living cells with high-quality extrinsic labels, which avoid over-expression artifacts and are available in a wide spectral range. This calls for a broadly applicable technology that can deliver such labels unambiguously to the cytosol of living cells. Here, we demonstrate that nanoparticle-sensitized photoporation can be used to this end as an emerging intracellular delivery technique. We replace the traditionally used gold nanoparticles with graphene nanoparticles as photothermal sensitizers to permeabilize the cell membrane upon laser irradiation. We demonstrate that the enhanced thermal stability of graphene quantum dots allows the formation of multiple vapor nanobubbles upon irradiation with short laser pulses, allowing the delivery of a variety of extrinsic cell labels efficiently and homogeneously into live cells. We demonstrate high-quality time-lapse imaging with confocal, total internal reflection fluorescence (TIRF), and Airyscan super-resolution microscopy. As the entire procedure is readily compatible with fluorescence (super resolution) microscopy, photoporation with graphene quantum dots has the potential to become the long-awaited generic platform for controlled intracellular delivery of fluorescent labels for live-cell imaging.

}, issn = {2047-7538}, doi = {10.1038/s41377-018-0048-3}, author = {Liu, Jing and Xiong, Ranhua and Brans, Toon and Lippens, Saskia and Parthoens, Eef and Zanacchi, Francesca Cella and Magrassi, Raffaella and Singh, Santosh K. and Kurungot, Sreekumar and Szunerits, Sabine and Bove, Hannelore and Ameloot, Marcel and Fraire, Juan C. and Teirlinck, Eline and Samal, Sangram Keshari and De Rycke, Riet and Houthaeve, Gaelle and De Smedt, Stefaan C. and Boukherroub, Rabah and Braeckmans, Kevin} } @article {46777, title = {Role of B site ions in bifunctional oxygen electrocatalysis: a structure-property correlation study on doped Ca(2)Fe(2)O(5)brownmillerites}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, year = {2020}, month = {JUL }, pages = {15520-15527}, type = {Article}, abstract = {

The role of B site doping with transition metals in brownmillerites, a perovskite related family of compounds, in bifunctional oxygen electrocatalysis,viz., simultaneous reduction and evolution reactions, is analysed. Ca2Fe1.9M0.1O5(M = Mn, Co, Ni, and Cu) is synthesised and structurally characterised by powder XRD and Rietveld refinement. Valence states of the surface B site ions are identified by X-ray photoelectron spectroscopy. Bifunctional oxygen electrochemistry is studied with the RDE and RRDE techniques and correlated with the structural and electronic parameters like oxygen non-stoichiometry and B site catalytic activity. Since the widely accepted electronic descriptors like e(g)filling may not be sufficient for explaining the bifunctional activity, B site electron donating capability as well as the extent of oxygen vacancies enhancing O(2)adsorption is also considered. Such structural parameters are also found to influence both the ORR and OER and based on this, Ni doping is proposed as advantageous for the bifunctional activity.

}, issn = {1463-9076}, doi = {10.1039/d0cp02391d}, author = {Thundiyil, Shibin and Vinod, C. P. and Kurungot, Sreekumar and Devi, R. Nandini} } @article {48119, title = {Recent advances in the metal-organic framework-based electrocatalysts for trifunctional electrocatalysis}, journal = {Dalton Transactions}, volume = {51}, year = {2022}, month = {SEP}, pages = {13573-13590}, type = {Review}, abstract = {

The sustainable energy technology is in great demand due to the depletion and the risks associated with the use of fossil fuels. Various energy technologies like regenerative fuel cells, zinc-air batteries, and overall water-splitting devices have a huge scope in the growth of green energy. The efficiency of these devices is reliant upon the multifunctional electrocatalysts, which include both bifunctional and trifunctional electrocatalysts. Among the different categories of the materials used for such multifunctional electrocatalysis, metal-organic-frameworks (MOFs) occupy a very consolidated place because of their high surface area, porosity, and many other unique physicochemical properties. However, the use of MOFs for the trifunctional electrocatalytic applications is in the budding phase and needs to be explored more. Further, most of these MOF-based trifunctional electrocatalysts are derived by pyrolyzing MOFs at high temperatures. Therefore, there is a need to develop more conductive MOFs which can be directly utilized for the trifunctional applications. In this frontier article, we present the latest reports on the MOF-based materials for trifunctional applications. The material design strategies of the MOF-based materials for trifunctional electrocatalysis have been discussed. The progressive improvements made with MOFs in electrocatalytic applications have been provided with emphasis on the structural, active site and compositional requirements. Finally, the challenges and viewpoints on the future development of the MOF-based materials for trifunctional electrocatalysis have been provided.

}, issn = {1477-9226}, doi = {10.1039/d2dt01981g}, author = {Devi, Bandhana and Koner, Rik Rani and Kurungot, Sreekumar} } @article {49080, title = {Role of nitrogen doping in modulating ruthenium nanocatalysts for enhanced electrochemical hydrogen evolution reaction in alkaline medium}, journal = {Chemistry of Materials }, volume = {36}, year = {2024}, month = {APR }, pages = {4262-4274}, type = {Article}, abstract = {

Nitrogen doping has become a fundamental approach to enhance the catalytic performance of carbon materials across various applications. The introduction of nitrogen creates defects and active sites, promoting the formation of small metal particles and strengthening the metal-support interaction within carbon materials. However, the challenge lies in developing sustainable and cost-effective methods for synthesizing nitrogen-doped carbon materials. In this study, we present a sustainable approach for the synthesis of ruthenium on nitrogen-doped carbon catalysts (Ru-CCP) using chitosan as a nitrogen and carbon source. Unlike traditional methods, our process avoids the use of additional nitrogen precursors and templates, streamlining the synthesis while using a renewable resource. The synthesized material exhibits an exceptional performance in the electrochemical hydrogen evolution reaction (HER) in alkaline conditions by achieving a current density of 25 mA cm(-2) at an impressively low overpotential of 46 mV, outperforming Pt/C under similar conditions. The detailed studies on structural and electronic properties of the materials using X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) revealed that the remarkable catalytic activity is upheld by the unique interplay between Ru delta+ and surface nitrogen moieties, notably pyridinic and pyrrolic nitrogen. Here, we demonstrate the control of particle size and electronic environment around the metal atom via the interaction of nitrogen and unravel the role of nitrogen doping in tuning the catalytic performance. In addition, this work offers insights into efficient HER catalyst design and emphasizes the potential of biomass-derived materials like chitosan in advancing clean hydrogen production for renewable energy applications.

}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.3c03169}, author = {Korampattu, Lavanya and Barik, Sidharth and Pandikassala, Ajmal and Urkude, Rajashri R. and Kurungot, Sreekumar and Dhepe, Paresh L.} }