3 research outputs found
Construction of S‑modified Amorphous Fe(OH)<sub>3</sub> on NiSe Nanowires as Bifunctional Electrocatalysts for Efficient Seawater Splitting
Seawater
electrolysis is valuable for hydrogen production, but
there are significant challenges such as severe Cl– corrosion and competition reaction of the chlorine evolution reaction
(CER) due to high Cl– concentrations. Here, a core–shell
structure was developed on the nickel foam substrate, consisting of
a sulfur-modified amorphous Fe(OH)3 layer on top of a crossing
NiSe nanowire (named S–Fe(OH)3/NiSe/NF). The S–Fe(OH)3/NiSe/NF electrode demonstrates outstanding catalytic performance
for both the hydrogen evolution reaction (HER) and the oxygen evolution
reaction (OER) in simulated and natural alkaline seawater electrolytes.
The overpotentials at 100 mA/cm2 for the OER in simulated
and natural alkaline seawater electrolytes are 234 and 232 mV, respectively.
For HER, the values are 331 and 341 mV, respectively, at a current
density of 100 mA/cm2. When S–Fe(OH)3/NiSe/NF serves as both the anode and cathode, the electrolyzer demonstrates
excellent performance with voltages of 1.85 and 1.87 V at 100 mA/cm2 in simulated and natural seawater electrolytes, respectively.
This electrolyzer holds significant promise for practical seawater
electrolysis
Large-Scale Production of V<sub>6</sub>O<sub>13</sub> Cathode Materials Assisted by Thermal Gravimetric Analysis–Infrared Spectroscopy Technology
The kilogram-scale
fabrication of V<sub>6</sub>O<sub>13</sub> cathode materials has been
notably assisted by in situ thermal gravimetric analysis (TGA)–infrared
spectroscopy (IR) technology. This technology successfully identified
a residue of ammonium metavanadate in commercial V<sub>6</sub>O<sub>13</sub>, which is consistent with the X-ray photoelectron spectroscopy
result. Samples of V<sub>6</sub>O<sub>13</sub> materials have been
fabricated and characterized by TGA–IR, scanning electron microscopy,
and X-ray diffraction. The initial testing results at 125 °C
have shown that test cells containing the sample prepared at 500 °C
show up to a 10% increase in the initial specific capacity in comparison
with commercial V<sub>6</sub>O<sub>13</sub>
Unraveling the Complex Delithiation and Lithiation Mechanisms of the High Capacity Cathode Material V<sub>6</sub>O<sub>13</sub>
V<sub>6</sub>O<sub>13</sub> is a
promising Li-ion battery cathode
material for use in the high temperature oil field environment. The
material exhibits a high capacity, and the voltage profile contains
several plateaus associated with a series of complex structural transformations,
which are not fully understood. The underlying mechanisms are central
to understanding and improving the performance of V<sub>6</sub>O<sub>13</sub>-based rechargeable batteries. In this study, we present <i>in situ</i> X-ray diffraction data that highlight an asymmetric
six-step discharge and five-step charge process, due to a phase that
is only formed on discharge. The Li<sub><i>x</i></sub>V<sub>6</sub>O<sub>13</sub> unit cell expands sequentially in <i>c</i>, <i>b</i>, and <i>a</i> directions during discharge
and reversibly contracts back during charge. The process is associated
with change of Li ion positions as well as charge ordering in Li<sub><i>x</i></sub>V<sub>6</sub>O<sub>13</sub>. Density functional
theory calculations give further insight into the electronic structures
and preferred Li positions in the different structures formed upon
cycling, particularly at high lithium contents, where no prior structural
data are available. The results shed light into the high specific
capacity of V<sub>6</sub>O<sub>13</sub> and are likely to aid in the
development of this material for use as a cathode for secondary lithium
batteries