@article { ISI:000311056800010, title = {3D Hexaporous carbon assembled from single-layer graphene as high performance supercapacitor}, journal = {Chemsuschem}, volume = {5}, number = {11}, year = {2012}, month = {OCT}, pages = {2159-2164}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {Electrochemistry, Energy storage, graphene, porous materials, Supercapacitors}, issn = {1864-5631}, doi = {10.1002/cssc.201200421}, author = {Yadav, Prasad and Banerjee, Abhik and Unni, Sreekuttan and Jog, Jyoti Prakash and Kurungot, Sreekumar and Ogale, Satishchandra} } @article { ISI:000308879000041, title = {Electrochemical preparation of luminescent graphene quantum dots from multiwalled carbon nanotubes}, journal = {Chemistry-A European Journal}, volume = {18}, number = {39}, year = {2012}, month = {SEP}, pages = {12522-12528}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Green luminescent, graphene quantum dots (GQDs) with a uniform size of 3, 5, and 8.2(+/- 0.3) nm in diameter were prepared electrochemically from MWCNTs in propylene carbonate by using LiClO4 at 90?degrees C, whereas similar particles of 23(+/- 2) nm were obtained at 30?degrees C under identical conditions. Both these sets of GQDs displayed a remarkable quantum efficiency of 6.3 and 5.1?\%, respectively. This method offers a novel strategy to synthesise size-tunable GQDs as evidenced by multiple characterisation techniques like transmission and scanning electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray diffraction (XRD). Photoluminescence of these GQDs can be tailored by size variation through a systematic change in key process parameters, like diameter of carbon nanotube, electric field, concentration of supporting electrolyte and temperature. GQDs are promising candidates for a variety of applications, such as biomarkers, nanoelectronic devices and chemosensors due to their unique features, like high photostability, biocompatibility, nontoxicity and tunable solubility in water.

}, keywords = {electrochemical synthesis, graphene, Nanostructures, photoluminescence, quantum dots}, issn = {0947-6539}, doi = {10.1002/chem.201201043}, author = {Shinde, Dhanraj B. and Pillai, Vijayamohanan K.} } @article { ISI:000315209900016, title = {Electrochemical resolution of multiple redox events for graphene quantum dots}, journal = {Angewandte Chemie-International Edition}, volume = {52}, number = {9}, year = {2013}, month = {JAN}, pages = {2482-2485}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {charging energy, differential pulse voltammetry, graphene, quantum dots, single-electron transfer}, issn = {1433-7851}, doi = {10.1002/anie.201208904}, author = {Shinde, Dhanraj B. and Pillai, Vijayamohanan K.} } @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 { ISI:000339729400018, title = {CVD synthesis of graphene nanoplates on MgO support}, journal = {Materials Science-Poland}, volume = {32}, number = {2}, year = {2014}, month = {JUN}, pages = {243-246}, publisher = {OFICYNA WYDAWNICZA POLITECHNIKI WROCLAWSKIEJ}, address = {WYBRZEZE WYSPIANSKIEGO 27, 50-370 WROCLAW, POLAND}, abstract = {

Synthesis of graphene directly on MgO has been carried out and the structural properties of the obtained material have been investigated. Few-layered graphene was produced by simple thermal decomposition of methane over MgO powder at 950 A degrees C in a CVD reactor. The samples were purified by 10 N HNO3 treatment, and studied by TEM, Raman spectroscopy, EDAX and SEM. TEM clearly indicated the formation of graphene. EDAX showed that the purified sample contained only carbon and no traces of MgO. The characteristic Raman features of graphene were also seen as D-band at 1316 cm(-1), G-band at 1602 cm(-1), and a small 2D-band at 2700 cm(-1) in the Raman spectra. The strong D-band suggests that the graphene possess large number of boundary defects. The small 2D-band indicates the formation of few-layered graphene.

}, keywords = {graphene, magnesium oxide, nanographene}, issn = {2083-1331}, doi = {10.2478/s13536-013-0193-6}, author = {Jugade, Ravin M. and Sharma, Shalini and Gokhale, Suresh} } @conference { ISI:000352795700066, title = {Enhancement in the field emission behavior of graphene in N-2/O-2 high vacuum ambience}, booktitle = {2014 27th International Vacuum Nanoelectronics Conference (IVNC) }, series = {International Vacuum Nanoelectronics Conference}, year = {2014}, note = {27th International Vacuum Nanoelectronics Conference (IVNC), Engelberg, SWITZERLAND, JUL 06-10, 2014}, month = {JUL}, publisher = {IEEE, 345 E 47th ST, New York, NY 10017 USA}, organization = {IEEE, 345 E 47th ST, New York, NY 10017 USA}, address = {Engelberg, Switzerland}, abstract = {

Herein we report, pressure dependent field emission (FE) behaviour of a few-layer graphene emitter. Gas dependent FE properties have been investigated in ultra high vacuum (UHV), as well as in N-2 and O-2 ambience at base pressure similar to 1x10(-6) torr. Interestingly, the graphene emitter when operated in N-2/O-2 ambience exhibits lower turn-on field and higher emission current density, as compared to the UHV conditions. The emission current stability investigated at preset value of similar to 1 mu A over the period of more than 2 hrs is found better in the N2 ambience and is characterized by fewer fluctuations, in contrast to the behaviour in the O-2 ambience. The observed enhanced electron emission behavior in N-2/O-2 ambience is attributed to modulation of the work function of graphene emitter.

}, keywords = {graphene, Pressure Dependent Field Emission}, isbn = {978-1-4799-5306-6}, issn = {2164-2370}, doi = {10.1109/IVNC.2014.6894791}, author = {Suryawanshi, S. R. and Kolhe, Pankaj S. and Gavhane, D. S. and Patil, S. S. and Chavan, P. G. and More, Mahendra A. and Late, Dattatray J.}, editor = {Tsujino, S. and Gobrecht, J. and Paraliev, M. and Braun, H. H. and Groening, O. and Feurer, T.} } @article { ISI:000337617500028, title = {Plasmon-enhanced photocurrent generation from click-chemically modified graphene}, journal = {Chemistry-A European Journal}, volume = {20}, number = {24}, year = {2014}, month = {JUN}, pages = {7402-7409}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

The visible-light response of Au nanoparticles (AuNPs) assembled on rGO through different molecular bridges was investigated by transient photocurrent generation. We prepared rGO with two self-assembled monolayers (SAMs), one linear and the other with aromatic triazoles through a click cycloaddition reaction. A fivefold photocurrent enhancement was observed for triazole linkers over the aminopropyltrimethoxysilane (APTMS) linker. Cyclic voltammetry (CV) and impedance measurements also suggest fast electron transfer on account of the low resistance offered by the click-modified rGO surface whereby introduction of triazoles offers the efficient bridge between the donor AuNPs and acceptor rGO.

}, keywords = {Gold, graphene, Nanoparticles, photophysics, surface plasmon resonance}, issn = {0947-6539}, doi = {10.1002/chem.201400403}, author = {Yenchalwar, Sandeep G. and Devarapalli, Rami Reddy and Deshmukh, Ashvini B. and Shelke, Manjusha V.} } @article { ISI:000330542900022, title = {Sequential electrochemical unzipping of single-walled carbon nanotubes to graphene ribbons revealed by in situ Raman spectroscopy and imaging}, journal = {ACS Nano}, volume = {8}, number = {1}, year = {2014}, month = {JAN}, pages = {234-242}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

We report an in situ Raman spectroscopic and microscopic investigation of the electrochemical unzipping of single-walled carbon nanotubes (SWNTs). Observations of the radial breathing modes (RBMs) using Raman spectral mapping reveal that metallic SWNTs are opened up rapidly followed by gradual unzipping of semiconducting SWNTs. Consideration of the resonant Raman scattering theory suggests that two metallic SWNTs with chiralities (10,4) and (12, 0) get unzipped first at a lower electrode potential (036 V) followed by the gradual unzipping of another two metallic tubes, (9, 3) and (10, 1), at a relatively higher potential (1.16 V). The semiconducting SWNTs with chiralities (11, 7) and (12, 5), however, get open up gradually at +/- 1.66 V. A rapid decrease followed by a subsequent gradual decrease in the metallicity of the SWNT ensemble as revealed from a remarkable variation of the peak width of the G band complies well with the variations of RBM. Cyclic voltammetry also gives direct evidence for unzipping in terms of improved capacitance after oxidation followed by more important removal of oxygen functionalities during the reduction step, as reflected in subtle changes of the morphology confirming the formation of graphene nanoribbons. The density functional-based tight binding calculations show additional dependence of chirality and diameter of nanotubes on the epoxide binding energies, which is in agreement with the Raman spectroscopic results and suggests a possible mechanism of unzipping determined by combined effects of the structural characteristics of SWNTs and applied field.

}, keywords = {density functional-based tight binding calculations, Electrochemistry, graphene, Raman spectral mapping, single-walled carbon nanotubes}, issn = {1936-0851}, doi = {10.1021/nn403289g}, author = {John, Robin and Shinde, Dhanraj B. and Liu, Lili and Ding, Feng and Xu, Zhiping and Vijayan, Cherianath and Pillai, Vijayamohanan K. and Pradeep, Thalappil} } @article { ISI:000351972400028, title = {Mechanically stable thermally cross linked poly(acrylic acid)/reduced graphene oxide aerogels}, journal = {ACS Applied Materials \& Interfaces}, volume = {7}, number = {11}, year = {2015}, month = {MAR}, pages = {6220-6229}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Graphene oxide (GO) aerogels, high porosity (\>99\%) low density (similar to 3-10 mg cm(-3)) porous materials with GO pore walls, are particularly attractive due to their lightweight, high surface area, and potential use in environmental remediation, superhydrophobic and superoleophilic materials, energy storage, etc. However, pure GO aerogels are generally weak and delicate which complicates their handling and potentially limits their commercial implementation. The focus of this work Vas to synthesize highly elastic, mechanically stable aerogels that are robust and easy to handle without substantially sacrificing their high porosity or low density. To overcome this challenge, a small amount of readily available and, thermally cross-linkable poly(acrylic acid) (PAA) was intermixed with GO to enhance the mechanical integrity Of the aerogel without disrupting other desirable characteristic properties. This method is a simple straightforward procedure that does not include multistep or complicated chemical reactions, and it produces aerogels with mass densities of about 4-6 mg cm(-3) and \>99.6\% porosity-that can reversibly support up to 10 000 times their weight with full recovery of their original volume. Finally; pressure sensing capabilities were demonstrated and their oil absorption capacities were measured to be around 120 g oil per g aerogel(-1) which highlights their potential Use in practical applications.

}, keywords = {aerogels, environmental remediation, graphene, Nanocomposites, poly(acrylic acid)}, issn = {1944-8244}, doi = {10.1021/acsami.5b00407}, author = {Ha, Heonjoo and Shanmuganathan, Kadhiravan and Ellison, Christopher J.} } @article { ISI:000357617800013, title = {Reduced graphene oxide composite with oxidizable manganese/cobalt mixed oxide for p-cresol oxidation by using molecular oxygen}, journal = {ChemPlusChem}, volume = {80}, number = {7}, year = {2015}, month = {JUL}, pages = {1164-1169}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A composite of graphene oxide (GO) with mixed oxide (MnCo) was prepared by using a solvothermal method. During the synthesis, both the reduction of GO and growth of metal oxides took place simultaneously. The as-prepared composite material was highly selective for the liquid-phase oxidation of p-cresol to form p-hydroxybenzaldehyde in 71\% yield within 1h. The composite material was characterised by SEM, X-ray photoelectron spectroscopy, high-resolution TEM and cyclic voltammetry (CV). A CV study revealed that the increase in the redox potential of the mixed oxide after being supported on GO, led to its higher activity of the catalyst for the oxidation reaction. The stability of the catalyst under the reaction conditions was studied by its successful reuse in three cycles.

}, keywords = {cyclic voltammetry, graphene, Oxidation, supported catalysts, transition metals}, issn = {2192-6506}, doi = {10.1002/cplu.201500053}, author = {Jha, Ajay and Patil, Sagar H. and Solanki, Bhanu P. and Ribeiro, Ana P. C. and Castro, Carlos A. N. and Patil, Kashinath R. and Coronas, Alberto and Rode, Chandrashekhar V.} } @article { ISI:000379967000006, title = {3D interconnected porous graphene sheets loaded with cobalt oxide nanoparticles for lithium-ion battery anodes}, journal = {Energy Technology}, volume = {4}, number = {7}, year = {2016}, month = {JUL}, pages = {816-822}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Nanomaterials with high surface-to-volume ratio and tunable electronic and optical properties have expanded their use in variety of applications, especially energy conversion and storage. Here we report on the synthesis of a cobalt oxide (Co3O4)/3D-interconnected porous graphene (PG) nanocomposite by using a simple solvothermal route and its application as a Li-ion battery anode. Among the different compositions investigated, the composite PG-600 (with 50\% PG) showed a discharge capacity of 700mAhg(-1) at a current density of 500mAg(-1) and maintained 90\% retention after 80cycles. The high surface area of the 3DPG sheets helps the Co3O4 nanoparticles to form a uniform dispersion on the surfaces. The increased surface area (accessibility) and electrical conductivity of the composite result in significant enhancement in the capacity, cycling stability, and rate capability than the native Co3O4 phase.

}, keywords = {Cobalt oxide, Energy storage, graphene, lithium-ion batteries, Nanocomposites}, issn = {2194-4288}, doi = {10.1002/ente.201500497}, author = {Puthusseri, Dhanya and Aravindan, Vanchiappan and Madhavi, Srinivasan and Ogale, Satishchandra} } @article {43888, title = {TiO2/RGO composites: Its achievement and factors involved in hydrogen production}, journal = {Renewable \&sustainable energy reviews}, volume = {76}, year = {2017}, month = {SEP}, pages = {1384-1392}, type = {Article}, abstract = {

The immense potential shown by TiO2 to participate as a designer material resulting into a new class of high performing photocatalyst has acclaimed it to become an important player in the designing and synthesis of various solar harvesting materials. This role has further been explored by the introduction of graphene into TiO2 matrix. TiO2/reduced graphene oxide (TiO2/RGO) or TiO2/graphene (TiO2/GR) has shown its prospects or relevance to be considered as the next generation photocatalyst for hydrogen production by its reported values in terms of producing hydrogen gas. Hence, there is a requirement of having a detailed up to date write up on the work done in this area in terms of its synthetic procedures, properties and its effect on hydrogen production. Herein, we discuss the different methods involved in the synthesis of such highly efficient materials followed by a brief explanation on its structural and morphological properties. Furthermore, a comparative study on the recent developments in terms of hydrogen evolution efficiency along with a mechanistic approach is also described. Finally, the current challenge and possibility of the future development in this direction is emphasized.

}, keywords = {Au-tio2 Photocatalysts, Evolution, Generation, graphene, Hydrogen generation, Nanocomposite, Nitrogen-doped Tio2, Photocatalysis, Photocatalytic H-2 Production, Recent Progress, Reduced graphene oxide, TiO2, Tio2-graphene Nanocomposites, Visible-light Irradiation, Water}, issn = {1364-0321}, doi = {10.1016/j.rser.2017.03.1}, author = {Gupta, Bhavana and Melvin, Ambrose A.} } @article {44488, title = {Temperature and pressure dependent Raman spectroscopy of plasma treated multilayer graphene nanosheets}, journal = {Diamond and Related Materials}, volume = {84}, year = {2018}, month = {APR }, pages = {146-156}, type = {Journal Article}, abstract = {

Understanding of the fine structure at the atomic level and properties of graphene by creating defects is important from the point of view of thermal and stress management. Here we report Raman spectroscopic studies on pristine and plasma treated multilayer graphene to explore the remarkable structure and phonon properties with temperature and pressure. Temperature dependent studies illustrate monotonic softening of G and G' bands in the temperature range 78 to 573 K. This process can be of fundamental importance in other promising and emerging nano and heterostructured materials. The pressure dependent Raman spectroscopic investigations on G-band of these samples were carried out up to 25 GPa using a diamond anvil cell. Comparatively weak and more compressible nature of the G band (E2g in-plane mode) as a function of applied pressure is found in plasma treated graphene. After pressure release, the samples recover to their original ordered structure. The present study is important for further understanding of the fine structure, properties and effect of defects in graphene, which can affect the atomic bonds, thermal expansion, specific heat, and thermal conductivity as well.

}, keywords = {graphene, high pressure, Phonon, Plasma treated graphene, Raman spectroscopy}, issn = {9259635}, doi = {10.1016/j.diamond.2018.03.021}, author = {Pawbake, Amit S. and Mishra, K. K. and Machuno, Luis G. B. and Gelamo, Rogerio V. and Ravindranathan, T. R. and Rout, Chandra Sekhar and Late, Dattatray J.} } @article {47010, title = {Ovalbumin-mediated synthesis and simultaneous functionalization of graphene with increased protein stability}, journal = {Green Chemistry Letters and Reviews}, volume = {13}, year = {2020}, month = {JAN }, pages = {60-67}, type = {Article}, abstract = {

In this article, we have shown an easy, one-step, protein-directed approach for the synthesis of water-soluble and functional graphene using ovalbumin. The obtained ovalbumin functionalized graphene was characterized by UV-visible spectroscopy, X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. Atomic force microscopy was used to check the attachment/functionalization of ovalbumin on grapheme sheets. It was shown that the functionalization of ovalbumin on grapheme sheets makes the protein more thermally stable compare to free ovalbumin, which has been shown by using sodium dodecyl sulfate polyacrylamide gel electrophoresis.

}, keywords = {Atomic force microscopy, graphene, graphene oxide, Ovalbumin, SDS-PAGE, thermal degradation}, issn = {1751-8253}, doi = {10.1080/17518253.2020.1725150}, author = {Ullah, Riaz and Khan, Shadab Ali and Aladresi, Aref Ali Mohammed and Alharbi, Sulaiman Ali and Chinnathambi, Arunachalam} } @article {46766, title = {In situ preparation of ionomer as a tool for triple-phase boundary enhancement in 3D graphene supported Pt catalyst}, journal = {Advanced Sustainable Systems}, volume = {5}, year = {2021}, month = {JAN}, pages = {2000125}, type = {Article}, abstract = {

For improving the performance of platinum electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), it is important to enhance the Pt utilization level in the catalyst systems. A high performing electrocatalyst (Pt/3DNG) is developed for PEMFC applications by using nitrogen-doped 3D graphene (3DNG) as the support material and an in situ grafted active {\textquoteleft}{\textquoteleft}triple-phase boundary{\textquoteright}{\textquoteright} to more precisely control the formation of the proton conducting ionomer interface at the active sites. Considering the 3D morphology of the system, during the electrode fabrication for realistic single-cell evaluation, the concept of in situ generation of the proton conducting-ionomer based {\textquoteleft}{\textquoteleft}active triple-phase boundary{\textquoteright}{\textquoteright} is introduced, which could potentially replace the conventional method of using Nafion ionomer for the electrode preparation. The monomers owing to their small-size can access the pores and inner regions of the 3DNG support, which on UV-curing, undergo polymerization and transform into an ionomer with an extended interfacial network into the nanoregimes of 3DNG. Single cell evaluation of the membrane electrode assembly in a high-temperature PEMFC by using phosphoric acid doped polybenzimidazole membrane demonstrates the utility of the present strategy.

}, keywords = {electrocatalysts, fuel cells, graphene, oxygen reduction reaction}, issn = {2366-7486}, doi = {10.1002/adsu.202000125, Early Access Date = JUL 2020}, author = {Gangadharan, Pranav K. and Vijayakumar, Vidyanand and Nediyirakkal, Shijil A. and Fernandez, Roshni Tresa and Siddharthan, V. Adhrika and Kurungot, Sreekumar} } @article {47372, title = {Synthesis of graphene from activated carbon at liquid nitrogen temperature and its detailed structural analysis}, journal = {Applied Physics A-Materials Science \& Processing}, volume = {127}, year = {2021}, month = {MAY}, pages = {319}, type = {Article}, abstract = {

The present study deals with the synthesis of graphene using thermal quenching of pre-heated activated carbon (a-C) (1370 K for 3 h) at liquid nitrogen temperature and its detailed structural analysis using XRD, TEM, FTIR and Raman spectroscopy. The analysis of lattice parameters (L-a, L-c,L- and d) of constituent nanographitic domains using XRD shows restoration of graphene-like structure in the resultant product (a-CL). TEM image reveals porosity and partially crystallinity (from SAED) in a-C. While thin layers of graphene are observed in the TEM images of a-CL Deconvoluted Raman spectra have been used to investigate the evolution of crystalline behaviour of a-C with temperature in view of Ferrari and Robertson{\textquoteright}s three-stage model. The evolution of G peak and increase in I-D/I-G reveals restoration of crystallinity in a-CL. The development of the D peak indicates disordering of graphite but ordering of amorphous carbon. The reported method is technologically beneficial for graphene synthesis for large number of applications such as supercapacitors, H-2 storage, gas separation and purification.

}, keywords = {activated carbon, Amorphous carbon, graphene, H-2 storage applications, Raman spectroscopy, Supercapacitors}, issn = {0947-8396}, doi = {10.1007/s00339-021-04416-w}, author = {Sharma, Preeti and Sharma, Geeta and Punia, Rajesh} } @article {48374, title = {Concurrent polyvalent interaction and electrocatalysis to improve lithium-sulfur battery performance}, journal = {Batteries \& Supercaps}, volume = {5}, year = {2022}, month = {FEB}, type = {Article}, abstract = {

Batteries with improved efficiency are desired. Li-S batteries are attractive due to their high specific capacity and energy density. However, sluggish sulfur redox reaction and polysulfide dissolution are significant challenges in Li-S batteries. In this work, we report graphene with doped layer to electrocatalyze the sluggish sulfur redox reaction. The doped layer comprises heteroatoms such as either N or N and S. The doped layer also comprises cations of Ni. We have chosen a {\textquoteleft}{\textquoteleft}doped layer on graphene{\textquoteright}{\textquoteright} over {\textquoteleft}{\textquoteleft}doped graphene{\textquoteright}{\textquoteright} to avoid defects in the basal plane of graphene. We found the doped layer comprising graphene (DLC-G) to electrocatalyze the polysulfide redox reaction. However, the interaction between the doped layer and polysulfide is still weak, hence the dissolution is not suppressed. To circumvent the polysulfide dissolution, graphene with cationic layer was prepared. We found that cations in the layer electrostatically attract the polysulfides due to the polyvalent interaction. Thus, the dissolution is suppressed. While using this material in the Li-S batteries, the specific capacity, energy density and power density were found to be 1345 mAh g(-1), 782 Wh kg(-1) and 4437 W kg(-1), respectively.

}, keywords = {electrocatalysis, graphene, lithium-sulfur battery, mechanical exfoliation, polyvalent interaction}, doi = {10.1002/batt.202100229}, author = {Kumar, Subramani and Krishnamoorthy, Kothandam} } @article {48721, title = {Can metal cations electrocatalyze sulfur redox reaction and suppress polysulfide shuttle?}, journal = {Batteries \& Supercaps}, volume = {6}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

In lithium-sulfur (Li-S) batteries, sulfur undergoes various changes. It switches between cyclic structure and linear structure. The charge on the sulfur varies between a neutral state and a negative charge-bearing state. Due to these changes, the sulfur/polysulfide dissolves in the battery electrolyte. Furthermore, the kinetics of the sulfur redox reaction is sluggish. Therefore, a material that can suppress sulfur/polysulfide dissolution and electrocatalyze sulfur redox reaction is needed. We hypothesize that the polysulfide dissolution can be suppressed if the host exhibits polyvalent electrostatic attraction. Polysulfide is a negative charge-bearing molecule; hence the host must comprise multiple positive charges. Nickel cations with other heteroatoms have been explored as a host in Li-S batteries. The heteroatoms impart additional interactions. The easier way to circumvent the effect of heteroatoms is the addition of metal salts. However, metal salts can either exhibit monovalent or divalent attraction with polysulfides. Those interactions are weak and we must have polyvalent interaction. Towards this objective, we have designed and synthesized a material that comprises multiple divalent cations that is also devoid of heteroatoms. The Li-S batteries fabricated using the metal cation immobilized graphene showed a maximum specific capacity of 1022 mAh/g at 0.1 C rate. Among the metal cations, nickel cations showed better performance than cobalt cations. Thus, we demonstrate that metal cations immobilized on Graphene can efficiently electrocatalyze the sluggish sulfur redox reaction and suppress the polysulfide dissolution.

}, keywords = {electrocatalysis, graphene, lithium-sulfur batteries, metal cations, polysulfides}, doi = {10.1002/batt.202300136}, author = {Kumar, Subramani and Swain, Gitanjali and Krishnamoorthy, Kothandam} }