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Structural, optoelectronic and electrochemical properties of nickel oxide films
No full textThin nickel oxide (NiO) films were deposited
by the electron beam evaporation technique. The films were
post annealed in air at 450–500 C for 5 h and the effect of
annealing on the structural, microstructural, electrical and
optical properties were studied. X-ray diffraction studies
indicated the polycrystalline nature of the films. The
microstructural parameters were evaluated. The band gap of
the films was found to be about 3.60 eV. Electrical resistivity
of the films was 4.5 9 10-4 X cm. FTIR studies
indicated a broad spectrum centered at 461.6 cm-1. Cyclic
voltammetry studies in 1 M KOH solution revealed good
electronic electrochromic behaviour
High-Capacity Sol-Gel Synthesis of LiNixCoyMn1-x-yO2 (0 e x, y e 0.5) Cathode Material for Use in Lithium Rechargeable Batteries
No full textSuccinic acid assisted sol-gel synthesized layered LiNixCoyMn1-x-yO2 (0 e x, y e 0.5) materials have been
studied as cathode materials for lithium rechargeable batteries. TG/DTA studies were performed on the gel
precursor and suggest the formation of a layered phase around 400 °C. The gel precursor was calcined at 850
°C and characterized by means of X-ray diffraction and FT-IR analyses and reveals that all of the synthesized
materials are found to be well-crystallized with an R-NaFeO2 layered structure. The effect of Co content on
the surface morphology has been examined by scanning electron microscopy, and X-ray photoelectron
spectroscopy studies indicate that the oxidation states of nickel, cobalt, and manganese are +2, +3, and +4,
respectively. The electrochemical galvanostatic charge/discharge cycling behavior of the synthesized layered
materials has been evaluated in the voltage range of 2.7-4.8 V at C/10 and C/5 rates using a 2016 coin-type
cell using 1 M LiPF6 in 1:1 EC/DEC as electrolyte. LiCo0.1Ni0.4Mn0.5O2 cathode material delivered the highest
average discharge capacity of ∼175 mAh/g at a C/10 rate, corresponding to a current density of 0.298 mA
cm-2 over the investigated 50 cycles
Self-Assembled Monolayers As Nucleating Centers for the Preparation of Multilayers of Catalytically Active Pt Films
No full textA soft route for the preparation of catalytically active multilayers of Pt films free from poisoning effects is
reported. The SAMs (self-assembled monolayers) were initially formed on the gold substrates and they act
as nucleating centers initiating the formation of multilayers of Pt on gold substrates. The nanoscale to mesoscale
structures of Pt thus prepared were characterized by SEM and XPS. The SAM-based Pt structures exhibited
well-defined hydrogen adsorption, desorption regions associated with very high charge indicating high surface
area Pt. The electrocatalytic activity of the multilayers of Pt was characterized by methanol oxidation and a
comparison was made with two commercial Pt catalyst preparations
Recycled waste paper—A new source of raw material for electric double-layer capacitors
No full textFor the first time, a new carbon–carbon composite electrode material for supercapacitors is prepared by
simple KOH activation ofwaste newspaper. The amorphous nature and surface morphology of the carbon
composite are investigated by X-ray diffraction (XRD), N2 adsorption/desorption and scanning electron
microscopy. The surface area and pore diameter are 416m2 g−1 and 5.9 nm, respectively. Electrochemical
characteristics are evaluated by cyclic voltammetry (CV) and charge–discharge tests in 6.0M KOH at a
1mAcm−2 current density. The CV results reveal amaximumspecific capacitance of 180 F g−1 at a 2mVs−1
scan rate and the data explore a development of new use for waste paper into a valuable energy storage
material
Pulse electrodeposition of tin from sulphate bath
No full textIn the present work, the pulse electrodeposition of tin from sulphate bath containing SnSO4, H2SO4, phenol sulphonic acid, gelatin and ß-napthol has been studied. The influences of pulsed current, duty cycle on the thickness, hardness and current efficiency of the tin deposit were
studied. Electrochemical corrosion studies of the deposited tin on mild steel were conducted by potentiodynamic polarisation and electrochemical impedance spectroscopy. Cyclic voltammetry studies using potential sweep of 10 mV s21 provide information about the potential ranges for tin
deposition and stripping. The tin deposit on a brass substrate has been investigated using XRD, SEM and AFM. The XRD analysis revealed that the tin plated is Sn(200) and crystalline. The morphology of tin deposit is a typical fine grained and granular structure as seen from SEM and
AFM
A process for the recovery of pure nickel sulphate from the spent nickel stripper solution
No full textThe present invention provides a process for the recovery of pure nickel sulphate from the spent nickel stripper solution using sulphuric acid for precipitating the organic materials and roasting the impure nickel sulfate crystals at optimum temperature and duration and finally employing active charcoal treatment to get pure nickel sulfate solution from which nickel sulfate salts are crystallized. The novelty of the present invention is that impure nickel sulphate salt crystallized from nickel stripper solution is decomposed to break the nickel proprietary organic complex at 300-600°C in the roasting operation of the impure salt to liberate nickel in the form of pure nickel oxid
On the observation of a huge lattice contraction and crystal habit modifications in LiMn2O4 prepared by a fuel assisted solution combustion
No full textTwo batches of poly-crystalline lithium manganate were prepared by a fuel assisted solution
combustion method. LiMn2O4(S) was prepared using starch as the fuel and LiMn2O4(P) was prepared
using poly vinyl alcohol (PVA) as the fuel. XRD studies indicated a significant and consistent shift in the
2y values of all the hkl peaks to higher values in LiMn2O4(P) compared to LiMn2O4(S) indicating a lattice
contraction in the former. TG/DTA studies indicated a higher formation temperature (25 1C higher) for
LiMn2O4(P). The higher formation temperature most likely promotes the oxidation of some Mn3+ to
Mn4+ with a lower ionic radius causing a lattice contraction. This hypothesis is confirmed through XPS
studies which indicated the presence of a higher fraction of Mn4+ in LiMn2O4(P) than that present in
LiMn2O4(S). A crystal shape algorithm was used to generate the crystal habits of lithium manganate
from their XRD data leading to an understanding on the exposed hkl planes in these materials. From the
atomic arrangement on the exposed hkl planes it is predicted that LiMn2O4(P) would be less prone to
manganese dissolution and hence would possess a higher cycle life when compared to LiMn2O4(S)
Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview
No full textPolymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during
the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by
several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity.
The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on
modified-Nafion membranes
Photoelectrochemical characteristics of brush electrodeposited dSexte1-x thin films
No full textCdSexTe1-x thin films were brush plated on titanium and conducting glass substrates from
the precursors at different substrate temperatures in the range of 30 - 80°C. X-ray
diffraction studies indicated the films to possess hexagonal structure irrespective of
composition. The strain and dislocation density decrease with increase of substrate
temperature. The crystallite size increased from 30 – 100 nm as the substrate temperature
increased. Optical band gap of the films varied in the range of 1.45 – 1.72 eV.
Photoelectrochemical cells were made with the electrodes of different composition. The
photo output was nearly equal to earlier reports