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High Performance Li2Ru1−yMnyO3 (0.2 ≤ y ≤ 0.8) Cathode Materials for Rechargeable Lithium-Ion Batteries: Their Understanding
No full textUnderstanding the origin of the high capacity
displayed by Li2MnO3−LiMO2 (M = Ni, Co) composites is essential
for improving their cycling and rate capability performances. To
address this issue, the Li2Ru1−yMnyO3 series between the iso-structural
layered end-members Li2MnO3 and Li2RuO3 was investigated. A
complete solid solution was found, with the 0.4 ≤ y ≤ 0.6 members
showing sustainable reversible capacities exceeding 220 mAh·g−1
centered around 3.6 V vs Li+/Li. The voltage−composition profiles
display a plateau on the first charge as compared to an S-type curve on
subsequent discharge which is maintained on the following charges/discharges, with therefore a lowering of the average voltage.
We show this profile to evolve upon long cycling due to a structural phase transition as deduced from XRD measurements.
Finally we demonstrate, via XPS measurements, the oxidation and reduction of ruthenium (Ru5+/Ru4+) during cycling together
with a partial activity of the Mn4+/Mn3+ redox couple. Moreover, we provide direct evidence for the reversibility of the O2− →
O− anionic process upon cycling, hence accounting for the high capacity displayed by these materials. This work, by capturing the
main redox processes pertaining to these materials, should facilitate their developmen
Enhanced efficiency of bifacial and back-illuminated Ti foil based flexible dye-sensitized solar cells by decoration of mesoporous SiO2 layer on TiO2 anode
No full textThe present study focuses on enhancing the efficiency of bifacial and back-illuminated dye-sensitized
solar cells (DSCs) by incorporating SiO2 mesoporous layer on TiO2 electrode. The performance of DSCs is
investigated by UVevisible spectroscopy, incident photon conversion efficiency (IPCE) and electrochemical
impedance spectroscopy (EIS). It is observed that the current ratio of back- to front-DSC increases
with the increase in the thickness of SiO2 layer, which in turn influences the incident light to
dyed-TiO2 electrode, especially in the wavelength of 400e600 nm. The Ti foil based flexible small
(0.28 cm2) and sub-module (5 cm � 10 cm) DSCs having this modification show high conversion efficiencies
of 6.76 and 5.54% respectively under 100 mW cm�2 (AM 1.5)
Thiolated Graphene – a New Platform for anchoring CdSe Quantum Dots for hybrid heterostructures
Get PDFEffective organization of small CdSe quantum dots on graphene sheets has been achieved by a simple solution exchange with thiol terminated graphene prepared by diazonium salt chemistry. This generic methodology of CdSe nanoparticles attachment to any graphene surface has remarkable implications in designing hybrid heterostructure
Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar, India
No full textCorrosion behaviour and biofouling characteristics of
mild steel in three different coastal locations in the Gulf of Mannar,India have been studied over a period of 24 months. Oyster fouling was predominant at Open sea - Tuticorin, while barnacle fouling was dominant at both Mandapam and Harbour - Tuticorin.
The rate of corrosion for 24 months exposure period was highest at Mandapam, where fouling was minimal. The surface of the mild steel was characterized by etchings & crevices beneath the hard foulers attached on it, at all the test locations. The depth of crevice caused by hard foulers was higher at Open sea - Tuticorin followed by Harbour - Tuticorin and Mandapam. The loss in ultimate tensile
strength was more in Open sea - Tuticorin than the other two
locations. Corrosion behaviour of mild steel is discussed based on the variation in the biofouling assemblage at the three test locations
Sunlight-enhanced calcareous deposition on cathodic stainless steel in natural seawater
No full textIn replicate series of experiments in natural seawater, one in full darkness and the other in a 1:1 diurnal cycle with as
little as 5% of natural solar illumination, sunlight promoted calcareous deposition on cathodic stainless steel surfaces.
As exemplified by scanning electron microscopy, the deposit that formed under the natural diurnal cycle, in the presence
of photosynthetic biofilms, was composed of finer calcareous crystals that provided more compact and more uniform
surface coverage than the one formed in the dark. The light-enhanced deposit also possessed better scale
properties, as suggested by X-ray analysis and electrochemical measurements. Sunlight enhancement of calcareous
deposition looked all the more conspicuous when day and night regimes were examined independently. These results
not only bear important implications for cathodic protection in marine waters, but also provide an intriguing analogy
to coral reef calcificatio
Microwave assisted polyol method for the preparation of Pt/C, Ru/C and PtRu/C nanoparticles and its application in electrooxidation of methanol
No full textA polyol process activated by microwave irradiation was implemented to prepare efficient Pt/C, Ru/C and
Pt1Ru1/C electrocatalysts for methanol oxidation with reducing synthesis cost and time. Study of the
post-synthesis mixture by UVevisible spectroscopy led to determine the minimum batch temperature
and synthesis time necessary for the complete reduction of metal salts. It was shown that disappearance
of metal salts and colloid formation took place after 5 min at 100 �C for Pt, 5 min at 130 �C for Ru and
5 min at 160 �C for Pt1Ru1. The PtRu catalyst characterizations by TGA, TEM and XRD indicated that the
nominal loading and nominal composition were achieved, and that the structure of this material consisted
of a mixture of Pt0.8Ru0.2 monocrystalline particles of ca. 2.5e3.0 nm, RuO2 nanoclusters and
probably Ru nanoclusters. Pt1Ru1/C catalyst displayed a high activity towards CO and methanol electrooxidation,
with onset potentials of ca. 0.2 V lower than those obtained on Pt/C catalysts, and a low
surface poisoning at 0.6 V vs. as demonstrated by chronoamperometry measurement RHE and in situ
infrared reflectance spectroscop
Deposition and optoelectronic properties of ITO (In2O3:Sn) thin films by Jet nebulizer spray (JNS) pyrolysis technique
No full textNanocrystalline ITO thin films were deposited
on glass substrates by a new spray pyrolysis route, Jet
nebulizer spray (JNS) pyrolysis technique, for the first time
at different substrate temperatures varying from 350 to
450 �C using a precursor containing indium and tin solution
with 90:10 at% concentration. The structural, optical
and electrical properties have been investigated as a
function of temperature. X-ray diffraction analysis showed
that the deposited films were well crystallized and polycrystalline
with cubic structure having (222) preferred
orientation. The optical band gap values calculated from
the transmittance spectra of all the ITO films showed a blue
shift of the absorbance edge from 3.60 to 3.76 eV revealing
the presence of nanocrystalline particles. AFM analysis
showed uniform surface morphology with very low surface
roughness values. XPS results showed the formation of ITO
films with In3? and Sn4? states. TEM results showed the
nanocrystalline nature with grain size about 12-15 nm and
SAED pattern confirmed cubic structure of the ITO films.
The electrical parameters like the resistivity, mobility and
carrier concentration are found as 1.82 9 10-3 X cm,
8.94 cm2/Vs and 4.72 9 1020 cm-3, respectively for ITO
film deposited at 400 �C. These results show that the ITO
films, prepared using the new JNS pyrolysis technique, have
the device quality optoelectronic properties when deposited
under the proposed conditions at 400 �C
Synthesis, Structure, and Electrochemical Properties of the Layered Sodium Insertion Cathode Material: NaNi1/3Mn1/3Co1/3O2
No full textA layered phase, NaNi1/3Mn1/3Co1/3O2 (NaNMC), isostructural
to NaCoO2 has been synthesized. Stoichiometric NaNMC crystallizes in a
rhombohedral R3̅m space group where Na is in an octahedral environment
(O3-Type). Galvanostatic cycling on NaNMC vs Na cell indicated
a reversible intercalation of 0.5 Na, leading to a capacity of 120 mAh·g−1 in
the voltage range of 2−3.75 V and indicating its possible application in Naion
batteries. The electrochemically driven Na insertion/deinsertion in
NaNMC is associated with several phase transitions and solid solution
regimes which are studied by in situ X-ray diffraction. Sodium deinsertion in
NaxNMC resulted in sequential phase transitions composed of biphasic and
monophasic domains. The composition driven structural evolution in
NaxNMC follows the sequence O3 ⇒ O1 ⇒ P3 ⇒ P1 phases with an
increased ‘c’ parameter, while the ‘a’ parameter remains almost unchanged
Solar powered lithium-ion battery incorporating high performing electrode materials
No full textThe development of portable electronic communities requires high performing and high power
lithium rechargeable batteries. Herein, we explore a new lithium ion battery combined with a new
carbon based anode and cobalt based cathode which delivers an energy output of 280 Wh kg21 and
cycling efficiency of 97% over the investigated 500 cycles (1 C rate) of the lithium ion cel
Naked eye detection of nitric oxide release from nitrosothiols aided by gold nanoparticles
No full textIn this work we have demonstrated that nitric oxide can be monitored
spectrophotometrically using cyclodextrin encapsulated
ferrocene. The detection course showed the colour change from
yellow to blue which can be detected with the naked eye. Also we
describe the catalytic effect of gold nanoparticles in enhancing nitric
oxide release from S-nitrosothiols