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Graphene and Graphene-Based Composites: A Rising Star in Water Purification - A Comprehensive Overview
No full textGraphene is an interesting two-dimensional carbon sheet possessing
single-layered atom thickness that confers unique physical
and chemical properties. The pristine graphene sheets have
some limited applications in water purification, but the modification
of graphene into the graphene composite by the incorporation
of some functional groups or nanoparticles on the
surface extensively increases its environmental applications. Recently,
graphene nanocomposites have found to show very
promising applications in all types of water purification. The
present review highlights the recent developments in the applications
of graphene and graphene-based composites as adsorbent,
catalyst, photocatalyst, electrocatalyst, photoelectrocatalyst,
and disinfection and desalination agent in
comprehensive water purification systems. We primarily focus
on the environmental engineering applications of graphene
nanocomposites as sorbent materials for the elimination of toxic
inorganic (cationic and anionic), organic, and mixed/multiple
pollutants, and as catalysts for the degradation of toxic organic
contaminants using catalytic oxidation, photocatalytic oxidation,
electrocatalytic oxidation, and photoelectrocatalytic oxidation.
We have also discussed the use and feasibility of graphene
nanocomposites in water disinfection and desalination.
Finally, the future challenges and perspectives are discussed
In-situ monitoring of redox processes of viologen at Au(hkl)single-crystal electrodes using electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy
No full textIn-situ Raman/SERS studies of molecular adsorption/reaction behaviors at well-defined electrochemical interfaces
are important for understanding the fundamentals of electrochemical processes. However, it is still a
great challenge to perform such studies on model single-crystal surfaces as the smooth surface cannot support
surface plasmon resonance (SPR). In this work, shell-isolated nanoparticle-enhanced Raman spectroscopy was
combined with an electrochemical method (EC-SHINERS) to study the adsorption and redox transformation of
a resonant molecule viologen HS-8V8H at Au(hkl) single-crystal electrodes. Changes in the molecular structure
with potential were identified on different single-crystal surfaces, which explained the transformation process
of viologen fromV2+ state to V•+ and then V0. Facet-dependent SERS enhancementwas also observed,which results
from the different imaginary part of the dielectric function on Au(111), Au(100) and Au(110), and is supported
by the FEM simulations. Furthermore, a nonlinear resonant Raman process has been directly observed
in our experiments, which is consistent with the simulation results. These findings increase our understanding
of the electrochemical behavior of molecules in model systems
Novel chelating agent assisted dual doped spinel via sol–gel method for lithium rechargeable batteries
No full textLiMn2O4 and LiCuxAlyMn2 − x − yO4 (x=0.50; y=0.05–0.50) powders have been synthesized via sol–gel method
for the first time using Margaric acid as chelating agent. The synthesized samples have been used to physical
and electrochemical characterization such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD),
Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission
electron microscopy (TEM) and electrochemical characterization viz., electrochemical galvanostatic cycling
studies, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). XRD
patterns of LiMn2O4 and LiCuxAlyMn2−x−yO4 confirm high degree of crystallinitywith better phase purity of synthesized
materials. FESEM images of parent LiMn2O4 depict the most of the particles that are in 0.5 μm while
LiCu0.5Al0.05Mn1.45O4 powders exhibiting ice-cube surface morphology with good agglomerated less particle
size of 50 nm. TEM images of spinel LiMn2O4 and LiCu0.5Al0.05Mn1.45O4 corroborate that all the synthesized particles
are nano-sized with uniformspherical and cloudy particlemorphology. LiMn2O4 samples calcined at 850 °C
deliver the high discharge capacity of 130 mA h g−1 in the first cyclewhile LiCu0.5Al0.05Mn1.45O4 samples deliver
120 mA h g−1 during the first cycle. Inter alia all the dopant compositions investigated, LiCu0.5Al0.05Mn1.45O4 delivers
the stable cycling performance of 119 and 115mAh g−1 in the 5th and 10th cyclewith lowcapacity fade of
0.1 and 0.1 mA h g−1 cycle−1 corresponding to columbic efficiency of 99 and 99%
Controlled reverse pulse electrosynthesized spikepiece-structured Ni/Ni(OH)2 interlayer nanoplates for electrochemical pseudocapacitor applications
No full textAn ultrathin Ni/Ni(OH)2 hybrid electrode has been synthesized using
a controlled reverse pulse modulated electrochemical approach and
demonstrated as an advanced pseudocapacitor material having a
remarkable specific capacitance and excellent cycling performanc
Perfluoro anion based binary and ternary ionic liquids as electrolytes for dye-sensitized solar cells
No full textIn this work, eight new ionic liquids (ILs) based on triethylammonium (TEA) or n-methylpiperidinium
(NMP) cations and perfluoro carboxylate (PFC) anions having different carbon chain lengths are synthesized
and their physico-chemical properties such as density, decomposition temperature, viscosity
and conductivity are determined. Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) with
binary ionic liquids electrolytes, containing the mixture of the synthesized ILs and 1-methyl-3-propyl
imidazolium iodide (PMII) (v/v ¼ 35/65), are evaluated. Among the different ILs, solar cells containing
NMP based ILs show higher VOC than that of TEA, whereas, higher JSC is noted for the DSSCs incorporated
with the latter when compared to the former. Further, the photo-current of the DSSCs decreases with the
increase of the carbon chain length of perfluoro carboxylate anionic group of ILs. The cell performance of
the DSSC containing ternary ionic liquids-based electrolytes compose of NMP-2C/TEA-2C/PMII (v/v/
v ¼ 28/7/65) exhibits a JSC of 12.99 mA cm�2, a VOC of 639.0 mV, a FF of 0.72, and a cell efficiency of 6.01%.
The extraordinary durability of the DSSC containing the above combination of electrolytes stored in dark
at 50 �C is proved to be unfailing up to 1200 h
An efficient electron transport material of tin oxide for planar structure perovskite solar cells
No full textThe photovoltaic performance of a perovskite solar cell based on a new electron conducting SnO2 film
prepared at low temperature using different solvents was investigated. SnO2 was selected as an electron
conducting medium due to its superior properties over TiO2, such as better antireflective properties,
higher electron mobility, more suitable band edges and a wider band gap. A SnO2 layer was developed by
spin-coating SnCl2 solution followed by annealing at 200 C in air. The low-temperature (200 C)
annealed SnO2 layer exhibits enhanced crystallization, high transmittance, and uniform surface
morphology using ethanol as a solvent rather than water. Solid state CuSCN hole conductor was used as
HTM for reducing the device cost. A planar solar cell fabricated with CH3NH3PbI3 perovskite infiltrated
SnO2 showed a power conversion efficiency of 8.38% with short-circuit current density of 18.99 mA cm�2
,
an open-circuit voltage of 0.96 mV and a fill factor of 45%. The devices were fabricated at >60% humidity
level at room temperature. The results suggest that SnO2 is an effective charge collection system for
CH3NH3PbI3 based planar perovskite solar cells. In addition, these results provide a new direction for the
future improvement of perovskite solar cells using new electron conducting layers
Targeting human telomeric G-quadruplex DNA with curcumin and its synthesized analogues under molecular crowding conditions
No full textThe formation of telomeric G-quadruplexes has been shown to inhibit telomerase activity. Indeed, a number
of small molecules capable of p-stacking with G-tetrads have shown the ability to inhibit telomerase activity
through the stabilization of G-quadruplexes. Curcumin displays a wide spectrum of medicinal properties
ranging from anti-bacterial, anti-viral, anti-protozoal, anti-fungal and anti-inflammatory to anti-cancer
activity. We have investigated the interactions of curcumin and its structural analogues with the human
telomeric sequence AG3(T2AG3)3 under molecular crowding conditions. Experimental studies indicated
the existence of a AG3(T2AG3)3/curcumin complex with binding affinity of 0.72 � 106 M1 under
molecular crowding conditions. The results from UV-visible absorption spectroscopy, a fluorescent TO
displacement assay, circular dichroism and molecular docking studies, imply that curcumin and their
analogues interact with G-quadruplex DNA via groove binding. While other analogs of curcumin studied
here bind to G-quadruplexes in a qualitatively similar manner their affinities are relatively lower in
comparison to curcumin. The Knoevenagel condensate, a methoxy-benzylidene derivative of curcumin,
also exhibited significant binding to G-quadruplex DNA, although with two times decreased affinity. Our
study establishes the potential of curcumin as a promising natural product for G-quadruplex specific ligands
Simultaneous unzippingandsulfonationofmulti-walledcarbon nanotubestosulfonatedgraphenenanoribbonsfornanocomposite membranesinpolymerelectrolytefuelcells
No full textSimultaneous insituunzippingandsulfonationofmulti-walledcarbonnanotubes(MWCNTs)using
potassium sulfate(K2SO4) andsodiumdodecylbenzenesulfonate(SDBS)byahydrothermalsynthetic
routeiscarriedouttopreparesulfonatedgraphenenanoribbons(sGNR)asconfirmed byvariouschar-
acterization techniques.Further,nanocompositepolymerelectrolytemembranesofthiswithsulfonated
polyetheretherketone(SPEEK)showenhancedionexchangecapacity(IEC),protonconductivityand
wateruptakecomparedtothatofpristineSPEEKmembrane.Highermechanicalstabilityforthese
composite membranesisobservedincomparisonwithpristineSPEEKmembrane.Interestingly,these
SPEEK/sGNR compositeelectrolytemembranes(0.1wt%sGNR)whiletestinginaprotonexchange
membrane fuelcell(PEMFCs)test-bed,showsacurrentdensityof840mAcm�2 at 0.6V(peakpower
density of660mWcm�2) comparedtothecurrentdensityof480mAcm�2 at 0.6V(peakpowerdensity
of 331mWcm�2) forpristineSPEEK.Theaccelerateddurabilitytestforthemembranesconfirms that
composite membranesofSPEEK/sGNRarehighlydurableevenafter200hwithmarginaldropinOCV
with negligiblefuelcross-overupto175htosuggestitspotentialapplicationsinslewoffuturetech-
nologies includingpolymerelectrolytefuelcells,waterelectrolyzersandelectrochemicalsensor
Newer polyanionic bio-composite anode for sodium ion batteries
No full textNASICON frame work Na3V2(PO4)3 (NVP), wrapped by nitrogen and sulfur doped bio-carbon matrix
derived from human hair (HHC) has been investigated for its anode behavior in SIBs. Basically, NVP is
bestowed with a crystal structure of 3D open framework and a moderate theoretical capacity of 118 mAh
g�1, which are the twin advantages and motivation behind the selection of this material. Prepared
through a simple, scalable and facile method, the key problems associated with pristine NVP electrode
material, such as inferior conductivity and severe volume change have been mitigated to a great extent
through the formation of a composite containing HHC. Herein, HHC is a cheap and eco-friendly composite
additive, obtained from a universal bio-waste, viz., human hair and hence NVP/HHC qualifies itself
as a green composite. Interestingly, NVP/HHC-10 (in-situ) and NVP/HHC-20 (ex-situ) anodes show
excellent electrochemical performance in terms of cycling stability up to 500 cycles and rate capability @
2 A g�1, which are superior than similar category NVP anodes reported in the literature. Further, post
cycling structure and morphology of NVP/HHC composite anodes evidence the appreciable stability
bestowed with the select composition, which is found to get maintained upon extended cycles and even
after rate capability test
A highly sensitive NADH biosensor using nitrogen doped graphene modified electrodes
No full textThe present work describes the fabrication of highly sensitive and selective β-nicotinamide adenine dinucleotide
(NADH) sensor using nitrogen doped graphene (NDG). NDG modified glassy carbon electrode (GCE) exhibits
strong and stable electrocatalytic response towards NADH oxidation. A substantial (253 mV) decrease in the
overpotential for NADH oxidation reaction (compared to GCE) is observed at NDG/GCE. NDG was prepared
using hydrothermal procedure and characterized using spectroscopy and microscopy techniques. Furthermore,
amperometric responses of NDG/GCE have high sensitivity towards NADH oxidation at lower oxidation potential
and minimization of surface contamination. The fabricated NADH biosensor exhibited enhanced and reproducible
sensitivity of 0.16 μA/μM (S/N = 3) with a response time of b3 s and the calculated limit of detection is
0.37 μM. A linear dynamic range from0.5–12 μMwas observed for the fabricated biosensorwith a correlation coefficient
(R2) of 0.99. Moreover, the biosensor exhibited strong stability after prolonged usage. The oxidation
peak potential at the NDG/GCE remained unchanged even after 15 days, with minimum surface contamination.
Therefore, NDG materials are found useful and promising candidates for NADH detection and are attractive for
dehydrogenase based biosensor