5 research outputs found
Highly Efficient Removal of Organic Dyes from Waste Water Using Hierarchical NiO Spheres with High Surface Area
A facile solvothermal method has been developed for large-scale
preparation of uniform spheres of a nickel–ethylene glycol
complex (Ni-EG complex) with a hierarchical nanostructure. The dispersibility
and hierarchical structure of the Ni-EG particles can be tuned by
varying the concentration of additives added. On the basis of experimental
observations, a plausible mechanism has been proposed to understand
the formation process of the Ni-EG complex spheres. Calcining these
as-prepared Ni-EG complex spheres at 300 °C in air results in
uniform porous NiO spheres with a high specific surface area of 222
m<sup>2</sup> g<sup>–1</sup>. When served as the adsorbent
for Congo red in water, the colloidal suspension of the as-prepared
NiO hierarchical spheres exhibits a high adsorption capacity for the
dye removal, suggesting their potential use in water treatment
Rational Design of Self-Supported Ni<sub>3</sub>S<sub>2</sub> Nanosheets Array for Advanced Asymmetric Supercapacitor with a Superior Energy Density
We report a rationally
designed two-step method to fabricate self-supported
Ni<sub>3</sub>S<sub>2</sub> nanosheet arrays. We first used 2-methylimidazole
(2-MI), an organic molecule commonly served as organic linkers in
metal–organic frameworks (MOFs), to synthesize an α-NiÂ(OH)<sub>2</sub> nanosheet array as a precursor, followed by its hydrothermal
sulfidization into Ni<sub>3</sub>S<sub>2</sub>. The resulting Ni<sub>3</sub>S<sub>2</sub> nanosheet array demonstrated superior supercapacitance
properties, with a very high capacitance of about 1,000 F g<sup>–1</sup> being delivered at a high current density of 50 A g<sup>–1</sup> for 20,000 charge–discharge cycles. This performance is unparalleled
by other reported nickel sulfide-based supercapacitors and is also
advantageous compared to other nickel-based materials such as NiO
and NiÂ(OH)<sub>2</sub>. An asymmetric supercapacitor was then established,
exhibiting a very stable capacitance of about 200 F g<sup>–1</sup> at a high current density of 10 A g<sup>–1</sup> for 10,000
cycles and a surprisingly high energy density of 202 W h kg<sup>–1</sup>. This value is comparable to that of the lithium-ion batteries,
i.e., 180 W h kg<sup>–1</sup>. The potential of the material
for practical applications was evaluated by building a quasi-solid-state
asymmetric supercapacitor which showed good flexibility and power
output, and two of these devices connected in series were able to
power up 18 green light-emitting diodes
Stainless Steel Mesh-Supported NiS Nanosheet Array as Highly Efficient Catalyst for Oxygen Evolution Reaction
NickelÂ(II)
sulfide (NiS) nanosheets with a thickness of 10 nm and a size of 200
nm were facilely grown on stainless steel (SLS) meshes via a one-pot
hydrothermal method. This unique construction renders an excellent
electrical contact between the porous film of active NiS sheets and
the highly conductive substrate, which exhibits a superior catalytic
activity toward oxygen evolution reaction (OER). The NiS@SLS electrocatalyst
exhibits an unusually low overpotential of 297 mV (i.e., 1.524 V vs
RHE) at a current density of 11 mA·cm<sup>–2</sup>, and
an extra small Tafel slope of only 47 mV·dec<sup>–1</sup> proves an even more competitive performance at high to very high
current densities. This performance compares very favorably to other
Ni-based catalysts and even to the precious state-of-the-art IrO<sub>2</sub> or RuO<sub>2</sub> catalyst
H<sub>2</sub>O–EG-Assisted Synthesis of Uniform Urchinlike Rutile TiO<sub>2</sub> with Superior Lithium Storage Properties
A facile
green method to synthesize uniform nanostructured urchinlike
rutile TiO<sub>2</sub> is demonstrated. Titanium trichloride was selected
as the TiO<sub>2</sub> precursor, and a mixed solvent containing H<sub>2</sub>O and ethylene glycol was used. By using this binary medium,
the nucleation and crystal growth of rutile TiO<sub>2</sub> can be
regulated, giving rise to very uniform urchinlike structures with
tailorable sizes. As confirmed by the SEM and TEM analysis, large
particles with dense aggregation of needle-like building blocks or
small ones with loosely packed subunits could be obtained at different
reaction conditions. The as-prepared samples were applied as the anode
material for lithium-ion batteries, and they were shown to have superior
properties with a high reversible capacity of 140 mA h g<sup>–1</sup> at a high current rate of 10 C for up to 300 cycles, which is almost
unmatched by other rutile TiO<sub>2</sub>-based electrodes. A stable
capacity of 88 mA h g<sup>–1</sup> can also be delivered at
an extremely high rate of 50 C, suggesting the great potential of
the as-prepared product for high-rate lithium-ion batteries