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Abstract
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Cobalt tungstate (CoWO4) nanoparticles were
synthesized by a chemical precipitation reaction in aqueous
ambient involving direct addition of cobalt ion solution to
the solution of tungstate reagent. Optimization of the
synthesis procedure was carried out using Taguchi robust
design as statistical method. In order to controllable, simple
and fast synthesis of CoWO4 nanoparticles, effects of some
synthesis conditions such as reagents concentrations (i.e.,
cobalt and tungstate ions), flow rate of cobalt feeding and
temperature of the reactor on the particle size of synthesized
CoWO4 were investigated by the aid of an orthogonal
array (OA9). The results of optimization process showed
that CoWO4 nanoparticles could be prepared by controlling
the effective parameters and at optimum conditions of
synthesis procedure, the size of prepared CoWO4 particles
was about 55 nm. Chemical composition and microstructure
of the prepared CoWO4 nanoparticles were characterized
by means of XRD, SEM, TEM, FT-IR
spectroscopy, UV–Vis spectroscopy and fluorescence. The
supercapacitive behavior of the CoWO4 electrode has been
investigated by cyclic voltammetry, galvanostatic charge/
discharge and electrochemical impedance spectroscopy.
The CoWO4 electrode indicates high specific capacitance
of 378 F g-1 at scan rate of 2 mV s-1 in 2.0 M H2SO4
electrolyte. Therefore, the prepared electrode could be
potential electrode materials for supercapacitors. Moreover,
an excellent rate performance, good capacitance
retention (*95.5 %) was also observed during the continuous
4000 cycles.
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